Author name code: auchere ADS astronomy entries on 2022-09-14 author:"Auchere, Frederic" ------------------------------------------------------------------------ Title: What drives decayless kink oscillations in active region coronal loops on the Sun? Authors: Mandal, Sudip; Chitta, Lakshmi P.; Antolin, Patrick; Peter, Hardi; Solanki, Sami K.; Auchère, Frédéric; Berghmans, David; Zhukov, Andrei N.; Teriaca, Luca; Cuadrado, Regina A.; Schühle, Udo; Parenti, Susanna; Buchlin, Éric; Harra, Louise; Verbeeck, Cis; Kraaikamp, Emil; Long, David M.; Rodriguez, Luciano; Pelouze, Gabriel; Schwanitz, Conrad; Barczynski, Krzysztof; Smith, Phil J. Bibcode: 2022arXiv220904251M Altcode: We study here the phenomena of decayless kink oscillations in a system of active region (AR) coronal loops. Using high resolution observations from two different instruments, namely the Extreme Ultraviolet Imager (EUI) on board Solar Orbiter and the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory, we follow these AR loops for an hour each on three consecutive days. Our results show significantly more resolved decayless waves in the higher-resolution EUI data compared with the AIA data. Furthermore, the same system of loops exhibits many of these decayless oscillations on Day-2, while on Day-3, we detect very few oscillations and on Day-1, we find none at all. Analysis of photospheric magnetic field data reveals that at most times, these loops were rooted in sunspots, where supergranular flows are generally absent. This suggests that supergranular flows, which are often invoked as drivers of decayless waves, are not necessarily driving such oscillations in our observations. Similarly, our findings also cast doubt on other possible drivers of these waves, such as a transient driver or mode conversion of longitudinal waves near the loop footpoints. In conclusion, through our analysis we find that none of the commonly suspected sources proposed to drive decayless oscillations in active region loops seems to be operating in this event and hence, the search for that elusive wave driver needs to continue. Title: Quiet Sun Center to Limb Variation of the Linear Polarization Observed by CLASP2 Across the Mg II h and k Lines Authors: Rachmeler, L. A.; Bueno, J. Trujillo; McKenzie, D. E.; Ishikawa, R.; Auchère, F.; Kobayashi, K.; Kano, R.; Okamoto, T. J.; Bethge, C. W.; Song, D.; Ballester, E. Alsina; Belluzzi, L.; Pino Alemán, T. del; Ramos, A. Asensio; Yoshida, M.; Shimizu, T.; Winebarger, A.; Kobelski, A. R.; Vigil, G. D.; Pontieu, B. De; Narukage, N.; Kubo, M.; Sakao, T.; Hara, H.; Suematsu, Y.; Štěpán, J.; Carlsson, M.; Leenaarts, J. Bibcode: 2022ApJ...936...67R Altcode: 2022arXiv220701788R The CLASP2 (Chromospheric LAyer Spectro-Polarimeter 2) sounding rocket mission was launched on 2019 April 11. CLASP2 measured the four Stokes parameters of the Mg II h and k spectral region around 2800 Å along a 200″ slit at three locations on the solar disk, achieving the first spatially and spectrally resolved observations of the solar polarization in this near-ultraviolet region. The focus of the work presented here is the center-to-limb variation of the linear polarization across these resonance lines, which is produced by the scattering of anisotropic radiation in the solar atmosphere. The linear polarization signals of the Mg II h and k lines are sensitive to the magnetic field from the low to the upper chromosphere through the Hanle and magneto-optical effects. We compare the observations to theoretical predictions from radiative transfer calculations in unmagnetized semiempirical models, arguing that magnetic fields and horizontal inhomogeneities are needed to explain the observed polarization signals and spatial variations. This comparison is an important step in both validating and refining our understanding of the physical origin of these polarization signatures, and also in paving the way toward future space telescopes for probing the magnetic fields of the solar upper atmosphere via ultraviolet spectropolarimetry. Title: Automatic detection technique for solar filament oscillations in GONG data Authors: Luna, Manuel; Merou Mestre, Joan-René; Auchère, Frédéric Bibcode: 2022arXiv220905087L Altcode: Solar filament oscillations have been known for decades. Now thanks to the new capabilities of the new telescopes, these periodic motions are routinely observed. Oscillations in filaments show key aspects of their structure. A systematic study of filament oscillations over the solar cycle can shed light on the evolution of the prominences. This work is a proof of concept that aims to automatically detect and parameterise such oscillations using H$\alpha$ data from the GONG network of telescopes. The proposed technique studies the periodic fluctuations of every pixel of the H$\alpha$ data cubes. Using the FFT we compute the power spectral density (PSD). We define a criterion to consider whether it is a real oscillation or whether it is a spurious fluctuation. This consists in considering that the peak in the PSD must be greater than several times the background noise with a confidence level of 95\%. The background noise is well fitted to a combination of red and white noise. We applied the method to several observations already reported in the literature to determine its reliability. We also applied the method to a test case, which is a data set in which the oscillations of the filaments were not known a priori. The method shows that there are areas in the filaments with PSD above the threshold value. The periodicities obtained are in general agreement with the values obtained by other methods. In the test case, the method detects oscillations in several filaments. We conclude that the proposed spectral technique is a powerful tool to automatically detect oscillations in prominences using H$\alpha$ data. Title: A highly dynamic small-scale jet in a polar coronal hole Authors: Mandal, Sudip; Chitta, Lakshmi Pradeep; Peter, Hardi; Solanki, Sami K.; Cuadrado, Regina Aznar; Teriaca, Luca; Schühle, Udo; Berghmans, David; Auchère, Frédéric Bibcode: 2022A&A...664A..28M Altcode: 2022arXiv220602236M We present an observational study of the plasma dynamics at the base of a solar coronal jet, using high resolution extreme ultraviolet imaging data taken by the Extreme Ultraviolet Imager on board Solar Orbiter, and by the Atmospheric Imaging Assembly on board Solar Dynamics Observatory. We observed multiple plasma ejection events over a period of ∼1 h from a dome-like base that is ca. 4 Mm wide and is embedded in a polar coronal hole. Within the dome below the jet spire, multiple plasma blobs with sizes around 1−2 Mm propagate upwards to the dome apex with speeds of the order of the sound speed (ca. 120 km s−1). Upon reaching the apex, some of these blobs initiate flows with similar speeds towards the other footpoint of the dome. At the same time, high speed super-sonic outflows (∼230 km s−1) are detected along the jet spire. These outflows as well as the intensity near the dome apex appear to be repetitive. Furthermore, during its evolution, the jet undergoes many complex morphological changes, including transitions between the standard and blowout type eruption. These new observational results highlight the underlying complexity of the reconnection process that powers these jets and they also provide insights into the plasma response when subjected to rapid energy injection.

Movies associated to Figs. 1, 2, and 4 are available at https://www.aanda.org Title: Linking Small-scale Solar Wind Properties with Large-scale Coronal Source Regions through Joint Parker Solar Probe-Metis/Solar Orbiter Observations Authors: Telloni, Daniele; Zank, Gary P.; Sorriso-Valvo, Luca; D'Amicis, Raffaella; Panasenco, Olga; Susino, Roberto; Bruno, Roberto; Perrone, Denise; Adhikari, Laxman; Liang, Haoming; Nakanotani, Masaru; Zhao, Lingling; Hadid, Lina Z.; Sánchez-Cano, Beatriz; Verscharen, Daniel; Velli, Marco; Grimani, Catia; Marino, Raffaele; Carbone, Francesco; Mancuso, Salvatore; Biondo, Ruggero; Pagano, Paolo; Reale, Fabio; Bale, Stuart D.; Kasper, Justin C.; Case, Anthony W.; de Wit, Thierry Dudok; Goetz, Keith; Harvey, Peter R.; Korreck, Kelly E.; Larson, Davin; Livi, Roberto; MacDowall, Robert J.; Malaspina, David M.; Pulupa, Marc; Stevens, Michael L.; Whittlesey, Phyllis; Romoli, Marco; Andretta, Vincenzo; Deppo, Vania Da; Fineschi, Silvano; Heinzel, Petr; Moses, John D.; Naletto, Giampiero; Nicolini, Gianalfredo; Spadaro, Daniele; Stangalini, Marco; Teriaca, Luca; Capobianco, Gerardo; Capuano, Giuseppe E.; Casini, Chiara; Casti, Marta; Chioetto, Paolo; Corso, Alain J.; Leo, Yara De; Fabi, Michele; Frassati, Federica; Frassetto, Fabio; Giordano, Silvio; Guglielmino, Salvo L.; Jerse, Giovanna; Landini, Federico; Liberatore, Alessandro; Magli, Enrico; Massone, Giuseppe; Messerotti, Mauro; Pancrazzi, Maurizio; Pelizzo, Maria G.; Romano, Paolo; Sasso, Clementina; Schühle, Udo; Slemer, Alessandra; Straus, Thomas; Uslenghi, Michela; Volpicelli, Cosimo A.; Zangrilli, Luca; Zuppella, Paola; Abbo, Lucia; Auchère, Frédéric; Cuadrado, Regina Aznar; Berlicki, Arkadiusz; Ciaravella, Angela; Lamy, Philippe; Lanzafame, Alessandro; Malvezzi, Marco; Nicolosi, Piergiorgio; Nisticò, Giuseppe; Peter, Hardi; Solanki, Sami K.; Strachan, Leonard; Tsinganos, Kanaris; Ventura, Rita; Vial, Jean-Claude; Woch, Joachim; Zimbardo, Gaetano Bibcode: 2022ApJ...935..112T Altcode: The solar wind measured in situ by Parker Solar Probe in the very inner heliosphere is studied in combination with the remote-sensing observation of the coronal source region provided by the METIS coronagraph aboard Solar Orbiter. The coronal outflows observed near the ecliptic by Metis on 2021 January 17 at 16:30 UT, between 3.5 and 6.3 R above the eastern solar limb, can be associated with the streams sampled by PSP at 0.11 and 0.26 au from the Sun, in two time intervals almost 5 days apart. The two plasma flows come from two distinct source regions, characterized by different magnetic field polarity and intensity at the coronal base. It follows that both the global and local properties of the two streams are different. Specifically, the solar wind emanating from the stronger magnetic field region has a lower bulk flux density, as expected, and is in a state of well-developed Alfvénic turbulence, with low intermittency. This is interpreted in terms of slab turbulence in the context of nearly incompressible magnetohydrodynamics. Conversely, the highly intermittent and poorly developed turbulent behavior of the solar wind from the weaker magnetic field region is presumably due to large magnetic deflections most likely attributed to the presence of switchbacks of interchange reconnection origin. Title: The observed large scale equatorial UV corona: new perspectives with 'recent', 'future' and 'old' data Authors: Abbo, Lucia; Fineschi, Silvano; Parenti, Susanna; Romoli, Marco; Pancrazzi, Maurizio; Andretta, Vincenzo; Auchère, Frédéric; Susino, Roberto; Spadaro, Daniele; Nicolini, Gianalfredo; Giordano, Silvio; Zangrilli, Luca Bibcode: 2022cosp...44.1327A Altcode: In order to understand the sources and the physical mechanisms for the propagation of the Slow Solar Wind (SSW), it is essential to analyze solar data in the region which shapes the large scale structure in corona where the SSW is accelerated, such as streamers and boundaries coronal hole/streamer. The focus of this work is to trace the channels where the SSW escapes from the solar disk up to 5 solar radii in corona. We give an overview on how Solar Orbiter observations (remote sensing and in-situ) together with other space missions (i.e. SPP and PROBA-3) can give a major contribution to the study of the evolution of the streamer belt and global corona, of the role of the coronal magnetic field topology in controlling the solar wind dynamics and abundance, and of abundance anomalies in streamers and in boundaries CH/streamer. In particular, we study how to trace back some equatorial features from the extended corona to the disk. We analyse recent Metis observations in corona together with the Extreme Ultraviolet Imager (EUI) observations on disk and corona (by using the occulter). We also present results from SOHO observations in 1996-1997 (solar minimum), during which was observed a stable equatorial streamer belt with a typical dipole magnetic structure. We have analyzed data by UVCS, SUMER, CDS to trace large scale features and also sub-structures at very high spatial resolution from the disk up to 3 solar radii. This comparison and overlapping is still unique in solar physics and it can improve our knowledge about the origin, acceleration and propagation of the solar wind. Title: The Magnetic Origin of Solar Campfires: Observations by Solar Orbiter and SDO Authors: Panesar, Navdeep Kaur; Zhukov, Andrei; Berghmans, David; Auchere, Frederic; Müller, Daniel; Tiwari, Sanjiv Kumar; Cheung, Mark Bibcode: 2022cosp...44.2564P Altcode: Solar campfires are small-scale, short-lived coronal brightenings, recently observed in 174 Å images by Extreme Ultraviolet Imager (EUI) on board Solar Orbiter (SolO). Here we investigate the magnetic origin of 52 campfires, in quiet-Sun, using line-of-sight magnetograms from Solar Dynamics Observatory (SDO)/Helioseismic and Magnetic Imager (HMI) together with extreme ultraviolet images from SolO /EUI and SDO/Atmospheric Imaging Assembly (AIA). We find that the campfires are rooted at the edges of photospheric magnetic network lanes; (ii) most of the campfires reside above neutral lines and 77% of them appear at sites of magnetic flux cancelation between the majority-polarity magnetic flux patch and a merging minority-polarity flux patch, with a flux cancelation rate of ∼1018 Mx hr‑1; some of the smallest campfires come from the sites where magnetic flux elements were barely discernible in HMI; (iii) some of the campfires occur repeatedly from the same neutral line; (iv) in the large majority of instances (79%), campfires are preceded by a cool-plasma structure, analogous to minifilaments in coronal jets; and (v) although many campfires have "complex" structure, most campfires resemble small-scale jets, dots, or loops. Thus, "campfire" is a general term that includes different types of small-scale solar dynamic features. They contain sufficient magnetic energy (∼1026-1027 erg) to heat the solar atmosphere locally to 0.5-2.5 MK. Their lifetimes range from about 1 minute to over 1 hour, with most of the campfires having a lifetime of <10 minutes. The average lengths and widths of the campfires are 5400 ± 2500 km and 1600 ± 640 km, respectively. Our observations suggest that (a) the presence of magnetic flux ropes may be ubiquitous in the solar atmosphere and not limited to coronal jets and larger-scale eruptions that make CMEs, and (b) magnetic flux cancelation, most likely driven by magnetic reconnection in the lower atmosphere, is the fundamental process for the formation and triggering of most campfires. Title: Transient small-scale brightenings in the quiet solar corona: a model for campfires observed with Solar Orbiter Authors: Chen, Yajie; Peter, Hardi; Berghmans, David; Tian, Hui; Auchère, Frédéric; Przybylski, Damien Bibcode: 2022cosp...44.2557C Altcode: Recent observations by the Extreme Ultraviolet Imager (EUI) on board Solar Orbiter have revealed prevalent small-scale transient brightenings in the quiet solar corona termed "campfires". To understand the generation mechanism of these coronal brightenings, we constructed a self-consistent and time-dependent quiet-Sun model extending from the upper convection zone to the lower corona using a realistic three-dimensional radiation magnetohydrodynamic simulation. From the model we have synthesized the coronal emission in the EUI 174 passband. We identified several transient coronal brightenings similar to those in EUI observations. The size and lifetime of these coronal brightenings are mostly 0.5-4 Mm and ~2 min, respectively. These brightenings are generally located at a height of 2-4 Mm above the photosphere, and the local plasma is often heated above 1 MK. By examining the magnetic field structures before and after the occurrence of brightenings, we concluded that these coronal brightenings are generated by component magnetic reconnection between interacting bundles of magnetic field lines or neighboring field lines within highly twisted flux ropes. Occurring in the coronal part of the atmosphere, these events generally reveal no obvious signature of flux emergence or cancellation in photospheric magnetograms. These transient coronal brightenings may play an important role in heating of the local coronal plasma. Title: Automated technique for detecting oscillations in solar filaments Authors: Luna, Manuel; Auchere, Frederic; Mérou-Mestre, Joan-René Bibcode: 2022cosp...44.2425L Altcode: Solar prominences/filaments are cold plasma hanging in the hot corona. There is a much larger magnetic structure that hosts this cold plasma: the filament channel. It has proved that oscillations in solar prominences are common and give information about their filament channels. The systematic study of these oscillations over several solar cycles will give us relevant information about the dynamics and structure of the prominences as the magnetic stress evolves during the cycle. In this study, we propose an efficient method to detect and characterize the oscillations in solar filaments using H alpha data. This technique uses spectral methods where the periodogram is calculated for each pixel of the images in the time sequence. It is necessary to calculate the background noise and we consider that we have a positive detection when the significance is higher than 95%. In this study, we set the basis for a future large-scale study of these periodic motions in solar filaments. Title: Automatic detection of small-scale EUV brightenings observed by the Solar Orbiter/EUI Authors: Alipour, N.; Safari, H.; Verbeeck, C.; Berghmans, D.; Auchère, F.; Chitta, L. P.; Antolin, P.; Barczynski, K.; Buchlin, É.; Aznar Cuadrado, R.; Dolla, L.; Georgoulis, M. K.; Gissot, S.; Harra, L.; Katsiyannis, A. C.; Long, D. M.; Mandal, S.; Parenti, S.; Podladchikova, O.; Petrova, E.; Soubrié, É.; Schühle, U.; Schwanitz, C.; Teriaca, L.; West, M. J.; Zhukov, A. N. Bibcode: 2022A&A...663A.128A Altcode: 2022arXiv220404027A Context. Accurate detections of frequent small-scale extreme ultraviolet (EUV) brightenings are essential to the investigation of the physical processes heating the corona.
Aims: We detected small-scale brightenings, termed campfires, using their morphological and intensity structures as observed in coronal EUV imaging observations for statistical analysis.
Methods: We applied a method based on Zernike moments and a support vector machine (SVM) classifier to automatically identify and track campfires observed by Solar Orbiter/Extreme Ultraviolet Imager (EUI) and Solar Dynamics Observatory (SDO)/Atmospheric Imaging Assembly (AIA).
Results: This method detected 8678 campfires (with length scales between 400 km and 4000 km) from a sequence of 50 High Resolution EUV telescope (HRIEUV) 174 Å images. From 21 near co-temporal AIA images covering the same field of view as EUI, we found 1131 campfires, 58% of which were also detected in HRIEUV images. In contrast, about 16% of campfires recognized in HRIEUV were detected by AIA. We obtain a campfire birthrate of 2 × 10−16 m−2 s−1. About 40% of campfires show a duration longer than 5 s, having been observed in at least two HRIEUV images. We find that 27% of campfires were found in coronal bright points and the remaining 73% have occurred out of coronal bright points. We detected 23 EUI campfires with a duration greater than 245 s. We found that about 80% of campfires are formed at supergranular boundaries, and the features with the highest total intensities are generated at network junctions and intense H I Lyman-α emission regions observed by EUI/HRILya. The probability distribution functions for the total intensity, peak intensity, and projected area of campfires follow a power law behavior with absolute indices between 2 and 3. This self-similar behavior is a possible signature of self-organization, or even self-organized criticality, in the campfire formation process.

Supplementary material (S1-S3) is available at https://www.aanda.org Title: Abundance diagnostics in active regions with Solar Orbiter/SPICE Authors: Giunta, Alessandra; Peter, Hardi; Parenti, Susanna; Buchlin, Eric; Thompson, William; Auchere, Frederic; Kucera, Therese; Carlsson, Mats; Janvier, Miho; Fludra, Andrzej; Hassler, Donald M.; Grundy, Timothy; Sidher, Sunil; Guest, Steve; Leeks, Sarah; Fredvik, Terje; Young, Peter Bibcode: 2022cosp...44.2583G Altcode: With the launch of Solar Orbiter in February 2020, we are now able to fully explore the link between the solar activity on the Sun and the inner heliosphere. Elemental abundance measurements provide a key tracer to probe the source regions of the solar wind and to track it from the solar surface and corona to the heliosphere. Abundances of elements with low first ionisation potential (FIP) are enhanced in the corona relative to high-FIP elements, with respect to the photosphere. This is known as the FIP effect, which is measured as abundance bias (FIP bias) of low and high FIP elements. This effect is vital for understanding the flow of mass and energy through the solar atmosphere. The comparison between in-situ and remote sensing composition data, coupled with modelling, will allow us to trace back the source of heliospheric plasma. Solar Orbiter has a unique combination of in-situ and remote sensing instruments that will help to make such a comparison. In particular, the SPICE (Spectral Imaging of the Coronal Environment) EUV spectrometer records spectra in two wavelength bands, 70.4-79.0 nm and 97.3-104.9 nm. SPICE is designed to provide spectroheliograms using a core set of emission lines arising from ions of both low-FIP and high-FIP elements such as C, N, O, Ne, Mg, S and Fe. These lines are formed over a wide range of temperatures from 20,000 K to over 1 million K, enabling the analysis of the different layers of the solar atmosphere. SPICE spectroheliograms can be processed to produce FIP bias maps, which can be compared to in-situ measurements of the solar wind composition of the same elements. During the Solar Orbiter Cruise Phase, SPICE observed several active regions. We will present some of these observations and discuss the SPICE diagnostic potential to derive relative abundances (e.g., Mg/Ne) and the FIP bias in those regions. Title: The SPICE spectrograph on Solar Orbiter: an introduction and results from the first Orbits Authors: Auchère, Frédéric; Peter, Hardi; Parenti, Susanna; Buchlin, Eric; Thompson, William; Auchere, Frederic; Teriaca, Luca; Kucera, Therese; Carlsson, Mats; Janvier, Miho; Fludra, Andrzej; Giunta, Alessandra; Schuehle, Udo; Hassler, Donald M.; Grundy, Timothy; Sidher, Sunil; Fredvik, Terje; Plowman, Joseph; Aznar Cuadrado, Regina Bibcode: 2022cosp...44.1338A Altcode: The Spectral Imaging of the Coronal Environment (SPICE) instrument is the EUV imaging spectrometer on board the Solar Orbiter mission. With its ability to derive physical properties of the coronal plasma, SPICE is a key component of the payload to establish the connection between the source regions and the in-situ measurements of the solar wind. The spacecraft was successfully launched in February 2020 and completed its cruise phase in December 2021. During this period, the remote sensing instruments were mostly operated during limited periods of time for 'checkout' engineering activities and synoptic observations. Nonetheless, several of these periods provided enough opportunities already to obtain new insights on coronal physics. During the march 2022 perihelion - close to 0.3 AU - SPICE will provide its highest spatial resolution data so far. Coordinated observations between the remote sensing and in-situ instruments will provide the first opportunity to use the full potential of the Solar Orbiter mission. We will review the instrument characteristics and present initial results from the cruise phase and first close encounter. Title: Prominence eruption observed in He II 304 Å up to >6 R by EUI/FSI aboard Solar Orbiter Authors: Mierla, M.; Zhukov, A. N.; Berghmans, D.; Parenti, S.; Auchère, F.; Heinzel, P.; Seaton, D. B.; Palmerio, E.; Jejčič, S.; Janssens, J.; Kraaikamp, E.; Nicula, B.; Long, D. M.; Hayes, L. A.; Jebaraj, I. C.; Talpeanu, D. -C.; D'Huys, E.; Dolla, L.; Gissot, S.; Magdalenić, J.; Rodriguez, L.; Shestov, S.; Stegen, K.; Verbeeck, C.; Sasso, C.; Romoli, M.; Andretta, V. Bibcode: 2022A&A...662L...5M Altcode: 2022arXiv220515214M
Aims: We report observations of a unique, large prominence eruption that was observed in the He II 304 Å passband of the Extreme Ultraviolet Imager/Full Sun Imager telescope aboard Solar Orbiter on 15-16 February 2022.
Methods: Observations from several vantage points - Solar Orbiter, the Solar-Terrestrial Relations Observatory, the Solar and Heliospheric Observatory, and Earth-orbiting satellites - were used to measure the kinematics of the erupting prominence and the associated coronal mass ejection. Three-dimensional reconstruction was used to calculate the deprojected positions and speeds of different parts of the prominence. Observations in several passbands allowed us to analyse the radiative properties of the erupting prominence.
Results: The leading parts of the erupting prominence and the leading edge of the corresponding coronal mass ejection propagate at speeds of around 1700 km s−1 and 2200 km s−1, respectively, while the trailing parts of the prominence are significantly slower (around 500 km s−1). Parts of the prominence are tracked up to heights of over 6 R. The He II emission is probably produced via collisional excitation rather than scattering. Surprisingly, the brightness of a trailing feature increases with height.
Conclusions: The reported prominence is the first observed in He II 304 Å emission at such a great height (above 6 R).

Movies are available at https://www.aanda.org Title: Observation of Magnetic Switchback in the Solar Corona Authors: Telloni, Daniele; Zank, Gary P.; Stangalini, Marco; Downs, Cooper; Liang, Haoming; Nakanotani, Masaru; Andretta, Vincenzo; Antonucci, Ester; Sorriso-Valvo, Luca; Adhikari, Laxman; Zhao, Lingling; Marino, Raffaele; Susino, Roberto; Grimani, Catia; Fabi, Michele; D'Amicis, Raffaella; Perrone, Denise; Bruno, Roberto; Carbone, Francesco; Mancuso, Salvatore; Romoli, Marco; Da Deppo, Vania; Fineschi, Silvano; Heinzel, Petr; Moses, John D.; Naletto, Giampiero; Nicolini, Gianalfredo; Spadaro, Daniele; Teriaca, Luca; Frassati, Federica; Jerse, Giovanna; Landini, Federico; Pancrazzi, Maurizio; Russano, Giuliana; Sasso, Clementina; Berghmans, David; Auchère, Frédéric; Aznar Cuadrado, Regina; Chitta, Lakshmi P.; Harra, Louise; Kraaikamp, Emil; Long, David M.; Mandal, Sudip; Parenti, Susanna; Pelouze, Gabriel; Peter, Hardi; Rodriguez, Luciano; Schühle, Udo; Schwanitz, Conrad; Smith, Phil J.; Verbeeck, Cis; Zhukov, Andrei N. Bibcode: 2022arXiv220603090T Altcode: Switchbacks are sudden, large radial deflections of the solar wind magnetic field, widely revealed in interplanetary space by the Parker Solar Probe. The switchbacks' formation mechanism and sources are still unresolved, although candidate mechanisms include Alfvénic turbulence, shear-driven Kelvin-Helmholtz instabilities, interchange reconnection, and geometrical effects related to the Parker spiral. This Letter presents observations from the Metis coronagraph onboard Solar Orbiter of a single large propagating S-shaped vortex, interpreted as first evidence of a switchback in the solar corona. It originated above an active region with the related loop system bounded by open-field regions to the East and West. Observations, modeling, and theory provide strong arguments in favor of the interchange reconnection origin of switchbacks. Metis measurements suggest that the initiation of the switchback may also be an indicator of the origin of slow solar wind. Title: Validation of a Wave Heated 3D MHD Coronal-wind Model using Polarized Brightness and EUV Observations Authors: Parenti, Susanna; Réville, Victor; Brun, Allan Sacha; Pinto, Rui F.; Auchère, Frédéric; Buchlin, Éric; Perri, Barbara; Strugarek, Antoine Bibcode: 2022ApJ...929...75P Altcode: 2022arXiv220310876P The physical properties responsible for the formation and evolution of the corona and heliosphere are still not completely understood. 3D MHD global modeling is a powerful tool to investigate all the possible candidate processes. To fully understand the role of each of them, we need a validation process where the output from the simulations is quantitatively compared to the observational data. In this work, we present the results from our validation process applied to the wave turbulence driven 3D MHD corona-wind model WindPredict-AW. At this stage of the model development, we focus the work to the coronal regime in quiescent condition. We analyze three simulation results, which differ by the boundary values. We use the 3D distributions of density and temperature, output from the simulations at the time of around the first Parker Solar Probe perihelion (during minimum of the solar activity), to synthesize both extreme ultraviolet (EUV) and white-light-polarized (WL pB) images to reproduce the observed solar corona. For these tests, we selected AIA 193 Å, 211 Å, and 171 Å EUV emissions, MLSO K-Cor, and LASCO C2 pB images obtained on 2018 November 6 and 7. We then make quantitative comparisons of the disk and off limb corona. We show that our model is able to produce synthetic images comparable to those of the observed corona. Title: The magnetic drivers of campfires seen by the Polarimetric and Helioseismic Imager (PHI) on Solar Orbiter Authors: Kahil, F.; Hirzberger, J.; Solanki, S. K.; Chitta, L. P.; Peter, H.; Auchère, F.; Sinjan, J.; Orozco Suárez, D.; Albert, K.; Albelo Jorge, N.; Appourchaux, T.; Alvarez-Herrero, A.; Blanco Rodríguez, J.; Gandorfer, A.; Germerott, D.; Guerrero, L.; Gutiérrez Márquez, P.; Kolleck, M.; del Toro Iniesta, J. C.; Volkmer, R.; Woch, J.; Fiethe, B.; Gómez Cama, J. M.; Pérez-Grande, I.; Sanchis Kilders, E.; Balaguer Jiménez, M.; Bellot Rubio, L. R.; Calchetti, D.; Carmona, M.; Deutsch, W.; Fernández-Rico, G.; Fernández-Medina, A.; García Parejo, P.; Gasent-Blesa, J. L.; Gizon, L.; Grauf, B.; Heerlein, K.; Lagg, A.; Lange, T.; López Jiménez, A.; Maue, T.; Meller, R.; Michalik, H.; Moreno Vacas, A.; Müller, R.; Nakai, E.; Schmidt, W.; Schou, J.; Schühle, U.; Staub, J.; Strecker, H.; Torralbo, I.; Valori, G.; Aznar Cuadrado, R.; Teriaca, L.; Berghmans, D.; Verbeeck, C.; Kraaikamp, E.; Gissot, S. Bibcode: 2022A&A...660A.143K Altcode: 2022arXiv220213859K Context. The Extreme Ultraviolet Imager (EUI) on board the Solar Orbiter (SO) spacecraft observed small extreme ultraviolet (EUV) bursts, termed campfires, that have been proposed to be brightenings near the apexes of low-lying loops in the quiet-Sun atmosphere. The underlying magnetic processes driving these campfires are not understood.
Aims: During the cruise phase of SO and at a distance of 0.523 AU from the Sun, the Polarimetric and Helioseismic Imager on Solar Orbiter (SO/PHI) observed a quiet-Sun region jointly with SO/EUI, offering the possibility to investigate the surface magnetic field dynamics underlying campfires at a spatial resolution of about 380 km.
Methods: We used co-spatial and co-temporal data of the quiet-Sun network at disc centre acquired with the High Resolution Imager of SO/EUI at 17.4 nm (HRIEUV, cadence 2 s) and the High Resolution Telescope of SO/PHI at 617.3 nm (HRT, cadence 2.5 min). Campfires that are within the SO/PHI−SO/EUI common field of view were isolated and categorised according to the underlying magnetic activity.
Results: In 71% of the 38 isolated events, campfires are confined between bipolar magnetic features, which seem to exhibit signatures of magnetic flux cancellation. The flux cancellation occurs either between the two main footpoints, or between one of the footpoints of the loop housing the campfire and a nearby opposite polarity patch. In one particularly clear-cut case, we detected the emergence of a small-scale magnetic loop in the internetwork followed soon afterwards by a campfire brightening adjacent to the location of the linear polarisation signal in the photosphere, that is to say near where the apex of the emerging loop lays. The rest of the events were observed over small scattered magnetic features, which could not be identified as magnetic footpoints of the campfire hosting loops.
Conclusions: The majority of campfires could be driven by magnetic reconnection triggered at the footpoints, similar to the physical processes occurring in the burst-like EUV events discussed in the literature. About a quarter of all analysed campfires, however, are not associated to such magnetic activity in the photosphere, which implies that other heating mechanisms are energising these small-scale EUV brightenings. Title: The role of asymmetries in coronal rain formation during thermal non-equilibrium cycles Authors: Pelouze, Gabriel; Auchère, Frédéric; Bocchialini, Karine; Froment, Clara; Mikić, Zoran; Soubrié, Elie; Voyeux, Alfred Bibcode: 2022A&A...658A..71P Altcode: 2021arXiv211009975P Context. Thermal non-equilibrium (TNE) produces several observables that can be used to constrain the spatial and temporal distribution of solar coronal heating. Its manifestations include prominence formation, coronal rain, and long-period intensity pulsations in coronal loops. The recent observation of abundant periodic coronal rain associated with intensity pulsations allowed for these two phenomena to be unified as the result of TNE condensation and evaporation cycles. On the other hand, many observed intensity pulsation events show little to no coronal rain formation.
Aims: Our goal is to understand why some TNE cycles produce such abundant coronal rain, while others produce little to no rain.
Methods: We reconstructed the geometry of the periodic coronal rain event, using images from the Extreme Ultraviolet Imager (EUVI) onboard the Solar Terrestrial Relations Observatory (STEREO), and magnetograms from the Helioseismic and Magnetic Imager (HMI). We then performed 1D hydrodynamic simulations of this event for different heating parameters and variations of the loop geometry (9000 simulations in total). We compared the resulting behaviour to simulations of TNE cycles that do not produce coronal rain.
Results: Our simulations show that both prominences and TNE cycles (with and without coronal rain) can form within the same magnetic structure. We show that the formation of coronal rain during TNE cycles depends on the asymmetry of the loop and of the heating. Asymmetric loops are overall less likely to produce coronal rain, regardless of the heating. In symmetric loops, coronal rain forms when the heating is also symmetric. In asymmetric loops, rain forms only when the heating compensates for the asymmetry.

Movie associated to Fig. 5 is available at https://www.aanda.org Title: Empirical relations between the intensities of Lyman lines of H and He+ Authors: Gordino, M.; Auchère, F.; Vial, J. -C.; Bocchialini, K.; Hassler, D. M.; Bando, T.; Ishikawa, R.; Kano, R.; Kobayashi, K.; Narukage, N.; Trujillo Bueno, J.; Winebarger, A. Bibcode: 2022A&A...657A..86G Altcode: 2022arXiv220101519G Context. Empirical relations between major UV and extreme UV spectral lines are one of the inputs for models of chromospheric and coronal spectral radiances and irradiances. They are also needed for the interpretation of some of the observations of the Solar Orbiter mission.
Aims: We aim to determine an empirical relation between the intensities of the H I 121.6 nm and He II 30.4 nm Ly-α lines.
Methods: Images at 121.6 nm from the Chromospheric Lyman-Alpha Spectro Polarimeter (CLASP) and Multiple XUV Imager (MXUVI) sounding rockets were co-registered with simultaneous images at 30.4 nm from the EIT and AIA orbital telescopes in order to derive a spatially resolved relationship between the intensities.
Results: We have obtained a relationship between the H I 121.6 nm and He II 30.4 nm intensities that is valid for a wide range of solar features, intensities, and activity levels. Additional SUMER data have allowed the derivation of another relation between the H I 102.5 nm (Ly-β) and He II 30.4 nm lines for quiet-Sun regions. We combined these two relationships to obtain a Ly-α/Ly-β intensity ratio that is comparable to the few previously published results.
Conclusions: The relationship between the H I 121.6 nm and He II 30.4 nm lines is consistent with the one previously obtained using irradiance data. We have also observed that this relation is stable in time but that its accuracy depends on the spatial resolution of the observations. The derived Ly-α/Ly-β intensity ratio is also compatible with previous results. Title: Stereoscopy of extreme UV quiet Sun brightenings observed by Solar Orbiter/EUI Authors: Zhukov, A. N.; Mierla, M.; Auchère, F.; Gissot, S.; Rodriguez, L.; Soubrié, E.; Thompson, W. T.; Inhester, B.; Nicula, B.; Antolin, P.; Parenti, S.; Buchlin, É.; Barczynski, K.; Verbeeck, C.; Kraaikamp, E.; Smith, P. J.; Stegen, K.; Dolla, L.; Harra, L.; Long, D. M.; Schühle, U.; Podladchikova, O.; Aznar Cuadrado, R.; Teriaca, L.; Haberreiter, M.; Katsiyannis, A. C.; Rochus, P.; Halain, J. -P.; Jacques, L.; Berghmans, D. Bibcode: 2021A&A...656A..35Z Altcode: 2021arXiv210902169Z Context. The three-dimensional fine structure of the solar atmosphere is still not fully understood as most of the available observations are taken from a single vantage point.
Aims: The goal of the paper is to study the three-dimensional distribution of the small-scale brightening events ("campfires") discovered in the extreme-UV quiet Sun by the Extreme Ultraviolet Imager (EUI) aboard Solar Orbiter.
Methods: We used a first commissioning data set acquired by the EUI's High Resolution EUV telescope on 30 May 2020 in the 174 Å passband and we combined it with simultaneous data taken by the Atmospheric Imaging Assembly (AIA) aboard the Solar Dynamics Observatory in a similar 171 Å passband. The two-pixel spatial resolution of the two telescopes is 400 km and 880 km, respectively, which is sufficient to identify the campfires in both data sets. The two spacecraft had an angular separation of around 31.5° (essentially in heliographic longitude), which allowed for the three-dimensional reconstruction of the campfire position. These observations represent the first time that stereoscopy was achieved for brightenings at such a small scale. Manual and automatic triangulation methods were used to characterize the campfire data.
Results: The height of the campfires is located between 1000 km and 5000 km above the photosphere and we find a good agreement between the manual and automatic methods. The internal structure of campfires is mostly unresolved by AIA; however, for a particularly large campfire, we were able to triangulate a few pixels, which are all in a narrow range between 2500 and 4500 km.
Conclusions: We conclude that the low height of EUI campfires suggests that they belong to the previously unresolved fine structure of the transition region and low corona of the quiet Sun. They are probably apexes of small-scale dynamic loops heated internally to coronal temperatures. This work demonstrates that high-resolution stereoscopy of structures in the solar atmosphere has become feasible. Title: Demonstration of Chromospheric Magnetic Mapping with CLASP2.1 Authors: McKenzie, David; Ishikawa, Ryohko; Trujillo Bueno, Javier; Auchere, F.; Kobayashi, Ken; Winebarger, Amy; Kano, Ryouhei; Song, Donguk; Okamoto, Joten; Rachmeler, Laurel; De Pontieu, Bart; Vigil, Genevieve; Belluzzi, Luca; Alsina Ballester, Ernest; del Pino Aleman, Tanausu; Bethge, Christian; Sakao, Taro; Stepan, Jiri Bibcode: 2021AGUFMSH52A..06M Altcode: Probing the magnetic nature of the Suns atmosphere requires measurement of the Stokes I, Q, U and V profiles of relevant spectral lines (of which Q, U and V encode the magnetic field information). Many of the magnetically sensitive lines formed in the chromosphere and transition region are in the ultraviolet spectrum, necessitating observations above the absorbing terrestrial atmosphere. The Chromospheric Layer Spectro-Polarimeter (CLASP2) sounding rocket was flown successfully in April 2019, as a follow-on to the successful flight in September 2015 of the Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP). Both projects were funded by NASAs Heliophysics Technology and Instrument Development for Science (H-TIDeS) program to develop and test a technique for observing the Sun in ultraviolet light, and for quantifying the polarization of that light. By demonstrating successful measurement and interpretation of the polarization in hydrogen Lyman-alpha and the Mg II h and k spectral lines, the CLASP and CLASP2 missions are vital first steps towards routine quantitative characterization of the local thermal and magnetic conditions in the solar chromosphere. In October of 2021, we re-flew the CLASP2 payload with a modified observing program to further demonstrate the maturity of the UV spectropolarimetry techniques, and readiness for development into a satellite observatory. During the reflight, called CLASP2.1, the spectrograph slit was scanned across an active region plage to acquire a two-dimensional map of Stokes V/I, to demonstrate the ability of UV spectropolarimetry to yield chromospheric magnetic fields over a large area. This presentation will display preliminary results from the flight of CLASP2.1. Title: 3D modelling of Titov-Demoulin modified Flux Ropes propagation in the Solar Wind Authors: Regnault, Florian; Janvier, Miho; Strugarek, Antoine; Auchere, F.; Al-Haddad, Nada Bibcode: 2021AGUFMSH33A..04R Altcode: Interplanetary Coronal Mass Ejections (ICMEs) originate from the eruption of complex magnetic structures occurring in our stars atmosphere. They propagate in the interplanetary medium, where they can be probed by spacecraft. ICMEs are known to generate geomagnetic storms that can disturb our technologies on earth, this is why they are a subject of interest. Studying ICMEs could, therefore, allow us to predict and lower their impact in our technology. We present the results of the propagation simulation of a set of Titov-Demoulin flux ropes (Titov et al. 2014) with different magnetic fields and sizes at the initiation. This is done with the 3D MHD module of the PLUTO code. Our grid starts at the low corona and goes up to 2 astronomical units. This allows us to study the effect of the magnetic field intensity or the size of the flux rope at the initiation on its properties during the propagation, highlighting then the physical processes happening during their journey in the inner heliosphere. The evolution of the magnetic field of the flux rope during the propagation agrees with evolution laws deduced from in situ observations. We also simulate in situ profiles that spacecraft would have measured at Mercury and at Earth, and we compare with the results of Janvier et al. 2019 and Regnault et al. 2020. We find a good match between simulated in situ profiles and typical profiles obtained in these studies. The magnetic components of the simulated flux rope match well with what we are expecting from theory (Lundquist et al. 1950). This simulation helps us to have a better understanding of the physical mechanisms that happen during propagation of an ICME. Title: Full Vector Velocity Reconstruction Using Solar Orbiter Doppler Map Observations. Authors: Podladchikova, Olena; Harra, Louise; Barczynski, Krzysztof; Mandrini, Cristina; Auchere, F.; Berghmans, David; Buchlin, Eric; Dolla, Laurent; Mierla, Marilena; Parenti, Susanna; Rodriguez, Luciano Bibcode: 2021AGUFMNG35B0432P Altcode: The Solar Orbiter mission opens up opportunities forthe combined analysis of measurements obtained by solar imagers and spectrometers. For the first time, different space spectrometerswill be located at wide angles to each other, allowing three-dimensional (3D) spectroscopy of the solar atmosphere.The aim of this work is to prepare the methodology to facilitate the reconstruction of 3D vector velocities from two stereoscopicLOS Doppler velocity measurements using the Spectral Imaging of the Coronal Environment (SPICE) on board the Solar Orbiter andthe near-Earth spectrometers, while widely separated in space. We develop the methodology using the libraries designed earlier for the STEREO mission but applied to spectroscopicdata from the Hinode mission and the Solar Dynamics Observatory. We use well-known methods of static and dynamic solar rotationstereoscopy and the methods of EUV stereoscopic triangulation for optically-thin coronal EUV plasma emissions. We develop new algorithms using analytical geometry in space to determine the 3D velocity in coronal loops. We demonstrate our approach with the reconstruction of 3D velocity vectors in plasma flows along "open" and "closed"magnetic loops. This technique will be applied first to an actual situation of two spacecraft at different separations with spectrometers onboard (SPICE versus the Interface Region Imaging Spectrograph (IRIS) and Hinode imaging spectrometer) during the Solar Orbiternominal phase. We summarise how these observations can be coordinated. Title: Campfires observed by EUI: What have we learned so far? Authors: Berghmans, David; Auchere, F.; Zhukov, Andrei; Mierla, Marilena; Chen, Yajie; Peter, Hardi; Panesar, Navdeep; Chitta, Lakshmi Pradeep; Antolin, Patrick; Aznar Cuadrado, Regina; Tian, Hui; Hou, Zhenyong; Podladchikova, Olena Bibcode: 2021AGUFMSH21A..02B Altcode: Since its very first light images of the corona, the EUI/HRIEUV telescope onboard Solar Orbiter has observed small localised brightenings in the Quiet Sun. These small localised brightenings, have become known as campfires, and are observed with length scales between 400 km and 4000 km and durations between 10 sec and 200 sec. The smallest and weakest of these HRIEUV brightenings have not been previously observed. Simultaneous observations from the EUI High-resolution Lyman- telescope (HRILYA) do not show localised brightening events, but the locations of the HRIEUV events clearly correspond to the chromospheric network. Comparisons with simultaneous AIA images shows that most events can also be identified in the 17.1 nm, 19.3 nm, 21.1 nm, and 30.4 nm pass-bands of AIA, although they appear weaker and blurred. Some of the larger campfires have the appearance of small interacting loops with the brightening expanding from the contact point of the loops. Our differential emission measure (DEM) analysis indicated coronal temperatures. We determined the height for a few of these campfires to be between 1 and 5 Mm above the photosphere. We interpret these events as a new extension to the flare-microflare-nanoflare family. Given their low height, the EUI campfires could stand as a new element of the fine structure of the transition region-low corona, that is, as apexes of small-scale loops that undergo internal heating all the way up to coronal temperatures. 3D MHD simulations with the MURaM code revealed brightenings that are in many ways similar to the campfires by EUI. The brightenings in the simulations suggest that campfires are triggered by component reconnection inside flux bundles rather than flux emergence or cancellation. Nevertheless, some of the observed campfires can be clearly linked to flux cancellation events and, intriguingly, are preceded by an erupting cool plasma structure. Analysis of the dynamics of campfires revealed that some have the appearance of coronal microjets, the smallest coronal jets observed in the quiet Sun. The HRIEUV images also reveal transient jets on a somewhat bigger scale with repeated outflows on the order of 100 km s1. In this paper we will provide an overview of the campfire related phenomena that EUI has observed and discuss the possible relevance for coronal heating. Title: Stereoscopy of extreme UV quiet Sun brightenings observed by Solar Orbiter/EUI Authors: Zhukov, Andrei; Mierla, Marilena; Auchere, F.; Gissot, Samuel; Rodriguez, Luciano; Soubrie, Elie; Thompson, William; Inhester, Bernd; Nicula, Bogdan; Antolin, Patrick; Parenti, Susanna; Buchlin, Eric; Barczynski, Krzysztof; Verbeeck, Cis; Kraaikamp, Emil; Smith, Philip; Stegen, Koen; Dolla, Laurent; Harra, Louise; Long, David; Schuhle, Udo; Podladchikova, Olena; Aznar Cuadrado, Regina; Teriaca, Luca; Haberreiter, Margit; Katsiyannis, Athanassios; Rochus, Pierre; Halain, Jean-Philippe; Jacques, Lionel; Berghmans, David Bibcode: 2021AGUFMSH21A..03Z Altcode: We study the three-dimensional distribution of small-scale brightening events (campfires) discovered in the extreme-ultraviolet (EUV) quiet Sun by the EUI telescope onboard the Solar Orbiter mission. We use one of the first commissioning data sets acquired by the HRI_EUV telescope of EUI on 2020 May 30 in the 174 A passband, combined with the simultaneous SDO/AIA dataset taken in the very similar 171 A passband. The spatial resolution of the two telescopes is sufficient to identify the campfires in both datasets. The angular separation between the two spacecraft of around 31.5 degrees allowed for the three-dimensional reconstruction of the position of campfires. This is the first time that stereoscopy was achieved for structures at such a small scale. Manual and automatic triangulation methods were used. The height of campfires is between 1000 km and 5000 km above the photosphere, and there is a good agreement between the results of manual and automatic methods. The internal structure of campfires is mostly not resolved by AIA, but for a large campfire we could triangulate a few pixels, which are all in a narrow height range between 2500 and 4500 km. The low height of campfires suggests that they belong to the previously unresolved fine structure of the transition region and low corona of the quiet Sun. They are probably apexes of small-scale dynamic loops internally heated to coronal temperatures. This work demonstrates that high-resolution stereoscopy of structures in the solar atmosphere has become possible. Title: Extreme-UV quiet Sun brightenings observed by the Solar Orbiter/EUI Authors: Berghmans, D.; Auchère, F.; Long, D. M.; Soubrié, E.; Mierla, M.; Zhukov, A. N.; Schühle, U.; Antolin, P.; Harra, L.; Parenti, S.; Podladchikova, O.; Aznar Cuadrado, R.; Buchlin, É.; Dolla, L.; Verbeeck, C.; Gissot, S.; Teriaca, L.; Haberreiter, M.; Katsiyannis, A. C.; Rodriguez, L.; Kraaikamp, E.; Smith, P. J.; Stegen, K.; Rochus, P.; Halain, J. P.; Jacques, L.; Thompson, W. T.; Inhester, B. Bibcode: 2021A&A...656L...4B Altcode: 2021arXiv210403382B Context. The heating of the solar corona by small heating events requires an increasing number of such events at progressively smaller scales, with the bulk of the heating occurring at scales that are currently unresolved.
Aims: The goal of this work is to study the smallest brightening events observed in the extreme-UV quiet Sun.
Methods: We used commissioning data taken by the Extreme Ultraviolet Imager (EUI) on board the recently launched Solar Orbiter mission. On 30 May 2020, the EUI was situated at 0.556 AU from the Sun. Its High Resolution EUV telescope (HRIEUV, 17.4 nm passband) reached an exceptionally high two-pixel spatial resolution of 400 km. The size and duration of small-scale structures was determined by the HRIEUV data, while their height was estimated from triangulation with simultaneous images from the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory mission. This is the first stereoscopy of small-scale brightenings at high resolution.
Results: We observed small localised brightenings, also known as `campfires', in a quiet Sun region with length scales between 400 km and 4000 km and durations between 10 s and 200 s. The smallest and weakest of these HRIEUV brightenings have not been previously observed. Simultaneous observations from the EUI High-resolution Lyman-α telescope (HRILya) do not show localised brightening events, but the locations of the HRIEUV events clearly correspond to the chromospheric network. Comparisons with simultaneous AIA images shows that most events can also be identified in the 17.1 nm, 19.3 nm, 21.1 nm, and 30.4 nm pass-bands of AIA, although they appear weaker and blurred. Our differential emission measure analysis indicated coronal temperatures peaking at log T ≈ 6.1 − 6.15. We determined the height for a few of these campfires to be between 1000 and 5000 km above the photosphere.
Conclusions: We find that `campfires' are mostly coronal in nature and rooted in the magnetic flux concentrations of the chromospheric network. We interpret these events as a new extension to the flare-microflare-nanoflare family. Given their low height, the EUI `campfires' could stand as a new element of the fine structure of the transition region-low corona, that is, as apexes of small-scale loops that undergo internal heating all the way up to coronal temperatures. Title: Capturing transient plasma flows and jets in the solar corona Authors: Chitta, L. P.; Solanki, S. K.; Peter, H.; Aznar Cuadrado, R.; Teriaca, L.; Schühle, U.; Auchère, F.; Berghmans, D.; Kraaikamp, E.; Gissot, S.; Verbeeck, C. Bibcode: 2021A&A...656L..13C Altcode: 2021arXiv210915106C Intensity bursts in ultraviolet (UV) to X-ray wavelengths and plasma jets are typical signatures of magnetic reconnection and the associated impulsive heating of the solar atmospheric plasma. To gain new insights into the process, high-cadence observations are required to capture the rapid response of plasma to magnetic reconnection as well as the highly dynamic evolution of jets. Here, we report the first 2 s cadence extreme-UV observations recorded by the 174 Å High Resolution Imager of the Extreme Ultraviolet Imager on board the Solar Orbiter mission. These observations, covering a quiet-Sun coronal region, reveal the onset signatures of magnetic reconnection as localized heating events. These localized sources then exhibit repeated plasma eruptions or jet activity. Our observations show that this spatial morphological change from localized sources to jet activity could occur rapidly on timescales of about 20 s. The jets themselves are intermittent and are produced from the source region on timescales of about 20 s. In the initial phases of these events, plasma jets are observed to exhibit speeds, as inferred from propagating intensity disturbances, in the range of 100 km s−1 to 150 km s−1. These jets then propagate to lengths of about 5 Mm. We discuss examples of bidirectional and unidirectional jet activity observed to have been initiated from the initially localized bursts in the corona. The transient nature of coronal bursts and the associated plasma flows or jets along with their dynamics could provide a benchmark for magnetic reconnection models of coronal bursts and jets.

Movies are available at https://www.aanda.org Title: Propagating brightenings in small loop-like structures in the quiet-Sun corona: Observations from Solar Orbiter/EUI Authors: Mandal, Sudip; Peter, Hardi; Chitta, Lakshmi Pradeep; Solanki, Sami K.; Aznar Cuadrado, Regina; Teriaca, Luca; Schühle, Udo; Berghmans, David; Auchère, Frédéric Bibcode: 2021A&A...656L..16M Altcode: 2021arXiv211108106M Brightenings observed in solar extreme-ultraviolet images are generally interpreted as signatures of micro- or nanoflares occurring in the transition region or at coronal temperatures. Recent observations with the Extreme Ultraviolet Imager (EUI) on board Solar Orbiter have revealed the smallest of such brightenings (called campfires) in the quiet-Sun corona. Analyzing EUI 174 Å data obtained at a resolution of about 400 km on the Sun with a cadence of 5 s on 30 May 2020, we report here a number of cases in which these campfires exhibit propagating signatures along their apparently small (3-5 Mm) loop-like structures. The measured propagation speeds are generally between 25 km s−1 and 60 km s−1. If the loop plasma is assumed to be at a million Kelvin, these apparent motions would be slower than the local sound speed. Furthermore, these brightenings exhibit nontrivial propagation characteristics such as bifurcation, merging, reflection, and repeated plasma ejections. We suggest that these features are manifestations of the internal dynamics of these small-scale magnetic structures and could provide important insights into the dynamic response (∼40 s) of the loop plasma to the heating events and also into the locations of the heating events themselves.

Movies associated to Figs 2-5, A.1, and B.1 are available at https://www.aanda.org Title: The first coronal mass ejection observed in both visible-light and UV H I Ly-α channels of the Metis coronagraph on board Solar Orbiter Authors: Andretta, V.; Bemporad, A.; De Leo, Y.; Jerse, G.; Landini, F.; Mierla, M.; Naletto, G.; Romoli, M.; Sasso, C.; Slemer, A.; Spadaro, D.; Susino, R.; Talpeanu, D. -C.; Telloni, D.; Teriaca, L.; Uslenghi, M.; Antonucci, E.; Auchère, F.; Berghmans, D.; Berlicki, A.; Capobianco, G.; Capuano, G. E.; Casini, C.; Casti, M.; Chioetto, P.; Da Deppo, V.; Fabi, M.; Fineschi, S.; Frassati, F.; Frassetto, F.; Giordano, S.; Grimani, C.; Heinzel, P.; Liberatore, A.; Magli, E.; Massone, G.; Messerotti, M.; Moses, D.; Nicolini, G.; Pancrazzi, M.; Pelizzo, M. -G.; Romano, P.; Schühle, U.; Stangalini, M.; Straus, Th.; Volpicelli, C. A.; Zangrilli, L.; Zuppella, P.; Abbo, L.; Aznar Cuadrado, R.; Bruno, R.; Ciaravella, A.; D'Amicis, R.; Lamy, P.; Lanzafame, A.; Malvezzi, A. M.; Nicolosi, P.; Nisticò, G.; Peter, H.; Plainaki, C.; Poletto, L.; Reale, F.; Solanki, S. K.; Strachan, L.; Tondello, G.; Tsinganos, K.; Velli, M.; Ventura, R.; Vial, J. -C.; Woch, J.; Zimbardo, G. Bibcode: 2021A&A...656L..14A Altcode: Context. The Metis coronagraph on board Solar Orbiter offers a new view of coronal mass ejections (CMEs), observing them for the first time with simultaneous images acquired with a broad-band filter in the visible-light interval and with a narrow-band filter around the H I Ly-α line at 121.567 nm, the so-called Metis UV channel.
Aims: We show the first Metis observations of a CME, obtained on 16 and 17 January 2021. The event was also observed by the EUI/FSI imager on board Solar Orbiter, as well as by other space-based coronagraphs, such as STEREO-A/COR2 and SOHO/LASCO/C2, whose images are combined here with Metis data.
Methods: Different images are analysed here to reconstruct the 3D orientation of the expanding CME flux rope using the graduated cylindrical shell model. This also allows us to identify the possible location of the source region. Measurements of the CME kinematics allow us to quantify the expected Doppler dimming in the Ly-α channel.
Results: Observations show that most CME features seen in the visible-light images are also seen in the Ly-α images, although some features in the latter channel appear more structured than their visible-light counterparts. We estimated the expansion velocity of this event to be below 140 km s−1. Hence, these observations can be understood by assuming that Doppler dimming effects do not strongly reduce the Ly-α emission from the CME. These velocities are comparable with or smaller than the radial velocities inferred from the same data in a similar coronal structure on the east side of the Sun.
Conclusions: The first observations by Metis of a CME demonstrate the capability of the instrument to provide valuable and novel information on the structure and dynamics of these coronal events. Considering also its diagnostics capabilities regarding the conditions of the ambient corona, Metis promises to significantly advance our knowledge of such phenomena.

Movies are available at https://www.aanda.org Title: First observations from the SPICE EUV spectrometer on Solar Orbiter Authors: Fludra, A.; Caldwell, M.; Giunta, A.; Grundy, T.; Guest, S.; Leeks, S.; Sidher, S.; Auchère, F.; Carlsson, M.; Hassler, D.; Peter, H.; Aznar Cuadrado, R.; Buchlin, É.; Caminade, S.; DeForest, C.; Fredvik, T.; Haberreiter, M.; Harra, L.; Janvier, M.; Kucera, T.; Müller, D.; Parenti, S.; Schmutz, W.; Schühle, U.; Solanki, S. K.; Teriaca, L.; Thompson, W. T.; Tustain, S.; Williams, D.; Young, P. R.; Chitta, L. P. Bibcode: 2021A&A...656A..38F Altcode: 2021arXiv211011252F
Aims: We present first science observations taken during the commissioning activities of the Spectral Imaging of the Coronal Environment (SPICE) instrument on the ESA/NASA Solar Orbiter mission. SPICE is a high-resolution imaging spectrometer operating at extreme ultraviolet (EUV) wavelengths. In this paper we illustrate the possible types of observations to give prospective users a better understanding of the science capabilities of SPICE.
Methods: We have reviewed the data obtained by SPICE between April and June 2020 and selected representative results obtained with different slits and a range of exposure times between 5 s and 180 s. Standard instrumental corrections have been applied to the raw data.
Results: The paper discusses the first observations of the Sun on different targets and presents an example of the full spectra from the quiet Sun, identifying over 40 spectral lines from neutral hydrogen and ions of carbon, oxygen, nitrogen, neon, sulphur, magnesium, and iron. These lines cover the temperature range between 20 000 K and 1 million K (10 MK in flares), providing slices of the Sun's atmosphere in narrow temperature intervals. We provide a list of count rates for the 23 brightest spectral lines. We show examples of raster images of the quiet Sun in several strong transition region lines, where we have found unusually bright, compact structures in the quiet Sun network, with extreme intensities up to 25 times greater than the average intensity across the image. The lifetimes of these structures can exceed 2.5 hours. We identify them as a transition region signature of coronal bright points and compare their areas and intensity enhancements. We also show the first above-limb measurements with SPICE above the polar limb in C III, O VI, and Ne VIII lines, and far off limb measurements in the equatorial plane in Mg IX, Ne VIII, and O VI lines. We discuss the potential to use abundance diagnostics methods to study the variability of the elemental composition that can be compared with in situ measurements to help confirm the magnetic connection between the spacecraft location and the Sun's surface, and locate the sources of the solar wind.
Conclusions: The SPICE instrument successfully performs measurements of EUV spectra and raster images that will make vital contributions to the scientific success of the Solar Orbiter mission. Title: First light observations of the solar wind in the outer corona with the Metis coronagraph Authors: Romoli, M.; Antonucci, E.; Andretta, V.; Capuano, G. E.; Da Deppo, V.; De Leo, Y.; Downs, C.; Fineschi, S.; Heinzel, P.; Landini, F.; Liberatore, A.; Naletto, G.; Nicolini, G.; Pancrazzi, M.; Sasso, C.; Spadaro, D.; Susino, R.; Telloni, D.; Teriaca, L.; Uslenghi, M.; Wang, Y. -M.; Bemporad, A.; Capobianco, G.; Casti, M.; Fabi, M.; Frassati, F.; Frassetto, F.; Giordano, S.; Grimani, C.; Jerse, G.; Magli, E.; Massone, G.; Messerotti, M.; Moses, D.; Pelizzo, M. -G.; Romano, P.; Schühle, U.; Slemer, A.; Stangalini, M.; Straus, T.; Volpicelli, C. A.; Zangrilli, L.; Zuppella, P.; Abbo, L.; Auchère, F.; Aznar Cuadrado, R.; Berlicki, A.; Bruno, R.; Ciaravella, A.; D'Amicis, R.; Lamy, P.; Lanzafame, A.; Malvezzi, A. M.; Nicolosi, P.; Nisticò, G.; Peter, H.; Plainaki, C.; Poletto, L.; Reale, F.; Solanki, S. K.; Strachan, L.; Tondello, G.; Tsinganos, K.; Velli, M.; Ventura, R.; Vial, J. -C.; Woch, J.; Zimbardo, G. Bibcode: 2021A&A...656A..32R Altcode: 2021arXiv210613344R In this work, we present an investigation of the wind in the solar corona that has been initiated by observations of the resonantly scattered ultraviolet emission of the coronal plasma obtained with UVCS-SOHO, designed to measure the wind outflow speed by applying Doppler dimming diagnostics. Metis on Solar Orbiter complements the UVCS spectroscopic observations that were performed during solar activity cycle 23 by simultaneously imaging the polarized visible light and the H I Lyman-α corona in order to obtain high spatial and temporal resolution maps of the outward velocity of the continuously expanding solar atmosphere. The Metis observations, taken on May 15, 2020, provide the first H I Lyman-α images of the extended corona and the first instantaneous map of the speed of the coronal plasma outflows during the minimum of solar activity and allow us to identify the layer where the slow wind flow is observed. The polarized visible light (580-640 nm) and the ultraviolet H I Lyα (121.6 nm) coronal emissions, obtained with the two Metis channels, were combined in order to measure the dimming of the UV emission relative to a static corona. This effect is caused by the outward motion of the coronal plasma along the direction of incidence of the chromospheric photons on the coronal neutral hydrogen. The plasma outflow velocity was then derived as a function of the measured Doppler dimming. The static corona UV emission was simulated on the basis of the plasma electron density inferred from the polarized visible light. This study leads to the identification, in the velocity maps of the solar corona, of the high-density layer about ±10° wide, centered on the extension of a quiet equatorial streamer present at the east limb - the coronal origin of the heliospheric current sheet - where the slowest wind flows at about 160 ± 18 km s−1 from 4 R to 6 R. Beyond the boundaries of the high-density layer, the wind velocity rapidly increases, marking the transition between slow and fast wind in the corona. Title: Transient small-scale brightenings in the quiet solar corona: A model for campfires observed with Solar Orbiter Authors: Chen, Yajie; Przybylski, Damien; Peter, Hardi; Tian, Hui; Auchère, F.; Berghmans, D. Bibcode: 2021A&A...656L...7C Altcode: 2021arXiv210410940C Context. Recent observations by the Extreme Ultraviolet Imager (EUI) on board Solar Orbiter have characterized prevalent small-scale transient brightenings in the corona above the quiet Sun termed campfires.
Aims: In this study we search for comparable brightenings in a numerical model and then investigate their relation to the magnetic field and the processes that drive these events.
Methods: We used the MURaM code to solve the 3D radiation magnetohydrodynamic equations in a box that stretches from the upper convection zone to the corona. The model self-consistently produces a supergranular network of the magnetic field and a hot corona above this quiet Sun. For the comparison with the model, we synthesized the coronal emission as seen by EUI in its 174 Å channel, isolated the seven strongest transient brightenings, and investigated the changes of the magnetic field in and around these in detail.
Results: The transients we isolated have a lifetime of about 2 min and are elongated loop-like features with lengths around 1 Mm to 4 Mm. They tend to occur at heights of about 2 Mm to 5 Mm above the photosphere, a bit offset from magnetic concentrations that mark the bright chromospheric network, and they reach temperatures of above 1 MK. As a result, they very much resemble the larger campfires found in observations. In our model most events are energized by component reconnection between bundles of field lines that interact at coronal heights. In one case, we find that untwisting a highly twisted flux rope initiates the heating.
Conclusions: Based on our study, we propose that the majority of campfire events found by EUI are driven by component reconnection and our model suggests that this process significantly contributes to the heating of the corona above the quiet Sun.

Movies associated to Figs. 2, 4, 5, and A1 are available at https://www.aanda.org Title: Stereoscopic measurements of coronal Doppler velocities Authors: Podladchikova, O.; Harra, L.; Barczynski, K.; Mandrini, C. H.; Auchère, F.; Berghmans, D.; Buchlin, É.; Dolla, L.; Mierla, M.; Parenti, S.; Rodriguez, L. Bibcode: 2021A&A...655A..57P Altcode: 2021arXiv210802280P Context. The Solar Orbiter mission, with an orbit outside the Sun-Earth line and leaving the ecliptic plane, opens up opportunities for the combined analysis of measurements obtained by solar imagers and spectrometers. For the first time different space spectrometers will be located at wide angles to each other, allowing three-dimensional (3D) spectroscopy of the solar atmosphere.
Aims: The aim of this work is to prepare a methodology to facilitate the reconstruction of 3D vector velocities from two stereoscopic line of sight (LOS) Doppler velocity measurements using the Spectral Imaging of the Coronal Environment (SPICE) on board the Solar Orbiter and the near-Earth spectrometers, while widely separated in space.
Methods: We developed the methodology using the libraries designed earlier for the STEREO mission, but applied to spectroscopic data from the Hinode mission and the Solar Dynamics Observatory. We used well-known methods of static and dynamic solar rotation stereoscopy and the methods of extreme ultraviolet (EUV) stereoscopic triangulation for optically thin coronal EUV plasma emissions. We developed new algorithms using analytical geometry in space to determine the 3D velocity in coronal loops.
Results: We demonstrate our approach with the reconstruction of 3D velocity vectors in plasma flows along `open' and `closed' magnetic loops. This technique will be applied to an actual situation of two spacecraft at different separations with spectrometers on board during the Solar Orbiter nominal phase: SPICE versus the Interface Region Imaging Spectrograph (IRIS) and Hinode imaging spectrometer. We summarise how these observations can be coordinated.

Movies associated to Fig. 1 are available at https://www.aanda.org Title: The Magnetic Origin of Solar Campfires Authors: Panesar, Navdeep K.; Tiwari, Sanjiv K.; Berghmans, David; Cheung, Mark C. M.; Müller, Daniel; Auchere, Frederic; Zhukov, Andrei Bibcode: 2021ApJ...921L..20P Altcode: 2021arXiv211006846P Solar campfires are fine-scale heating events, recently observed by Extreme Ultraviolet Imager (EUI) on board Solar Orbiter. Here we use EUI 174 Å images, together with EUV images from Solar Dynamics Observatory (SDO)/Atmospheric Imaging Assembly (AIA), and line-of-sight magnetograms from SDO/Helioseismic and Magnetic Imager (HMI) to investigate the magnetic origin of 52 randomly selected campfires in the quiet solar corona. We find that (i) the campfires are rooted at the edges of photospheric magnetic network lanes; (ii) most of the campfires reside above the neutral line between majority-polarity magnetic flux patch and a merging minority-polarity flux patch, with a flux cancelation rate of ~1018 Mx hr-1; (iii) some of the campfires occur repeatedly from the same neutral line; (iv) in the large majority of instances, campfires are preceded by a cool-plasma structure, analogous to minifilaments in coronal jets; and (v) although many campfires have "complex" structure, most campfires resemble small-scale jets, dots, or loops. Thus, "campfire" is a general term that includes different types of small-scale solar dynamic features. They contain sufficient magnetic energy (~1026-1027 erg) to heat the solar atmosphere locally to 0.5-2.5 MK. Their lifetimes range from about 1 minute to over 1 hr, with most of the campfires having a lifetime of <10 minutes. The average lengths and widths of the campfires are 5400 ± 2500 km and 1600 ± 640 km, respectively. Our observations suggest that (a) the presence of magnetic flux ropes may be ubiquitous in the solar atmosphere and not limited to coronal jets and larger-scale eruptions that make CMEs, and (b) magnetic flux cancelation is the fundamental process for the formation and triggering of most campfires. Title: Exploring the Solar Wind from Its Source on the Corona into the Inner Heliosphere during the First Solar Orbiter-Parker Solar Probe Quadrature Authors: Telloni, Daniele; Andretta, Vincenzo; Antonucci, Ester; Bemporad, Alessandro; Capuano, Giuseppe E.; Fineschi, Silvano; Giordano, Silvio; Habbal, Shadia; Perrone, Denise; Pinto, Rui F.; Sorriso-Valvo, Luca; Spadaro, Daniele; Susino, Roberto; Woodham, Lloyd D.; Zank, Gary P.; Romoli, Marco; Bale, Stuart D.; Kasper, Justin C.; Auchère, Frédéric; Bruno, Roberto; Capobianco, Gerardo; Case, Anthony W.; Casini, Chiara; Casti, Marta; Chioetto, Paolo; Corso, Alain J.; Da Deppo, Vania; De Leo, Yara; Dudok de Wit, Thierry; Frassati, Federica; Frassetto, Fabio; Goetz, Keith; Guglielmino, Salvo L.; Harvey, Peter R.; Heinzel, Petr; Jerse, Giovanna; Korreck, Kelly E.; Landini, Federico; Larson, Davin; Liberatore, Alessandro; Livi, Roberto; MacDowall, Robert J.; Magli, Enrico; Malaspina, David M.; Massone, Giuseppe; Messerotti, Mauro; Moses, John D.; Naletto, Giampiero; Nicolini, Gianalfredo; Nisticò, Giuseppe; Panasenco, Olga; Pancrazzi, Maurizio; Pelizzo, Maria G.; Pulupa, Marc; Reale, Fabio; Romano, Paolo; Sasso, Clementina; Schühle, Udo; Stangalini, Marco; Stevens, Michael L.; Strachan, Leonard; Straus, Thomas; Teriaca, Luca; Uslenghi, Michela; Velli, Marco; Verscharen, Daniel; Volpicelli, Cosimo A.; Whittlesey, Phyllis; Zangrilli, Luca; Zimbardo, Gaetano; Zuppella, Paola Bibcode: 2021ApJ...920L..14T Altcode: 2021arXiv211011031T This Letter addresses the first Solar Orbiter (SO)-Parker Solar Probe (PSP) quadrature, occurring on 2021 January 18 to investigate the evolution of solar wind from the extended corona to the inner heliosphere. Assuming ballistic propagation, the same plasma volume observed remotely in the corona at altitudes between 3.5 and 6.3 solar radii above the solar limb with the Metis coronagraph on SO can be tracked to PSP, orbiting at 0.1 au, thus allowing the local properties of the solar wind to be linked to the coronal source region from where it originated. Thanks to the close approach of PSP to the Sun and the simultaneous Metis observation of the solar corona, the flow-aligned magnetic field and the bulk kinetic energy flux density can be empirically inferred along the coronal current sheet with an unprecedented accuracy, allowing in particular estimation of the Alfvén radius at 8.7 solar radii during the time of this event. This is thus the very first study of the same solar wind plasma as it expands from the sub-Alfvénic solar corona to just above the Alfvén surface. Title: Magnetic imaging of the outer solar atmosphere (MImOSA) Authors: Peter, H.; Ballester, E. Alsina; Andretta, V.; Auchère, F.; Belluzzi, L.; Bemporad, A.; Berghmans, D.; Buchlin, E.; Calcines, A.; Chitta, L. P.; Dalmasse, K.; Alemán, T. del Pino; Feller, A.; Froment, C.; Harrison, R.; Janvier, M.; Matthews, S.; Parenti, S.; Przybylski, D.; Solanki, S. K.; Štěpán, J.; Teriaca, L.; Bueno, J. Trujillo Bibcode: 2021ExA...tmp...95P Altcode: The magnetic activity of the Sun directly impacts the Earth and human life. Likewise, other stars will have an impact on the habitability of planets orbiting these host stars. Although the magnetic field at the surface of the Sun is reasonably well characterised by observations, the information on the magnetic field in the higher atmospheric layers is mainly indirect. This lack of information hampers our progress in understanding solar magnetic activity. Overcoming this limitation would allow us to address four paramount long-standing questions: (1) How does the magnetic field couple the different layers of the atmosphere, and how does it transport energy? (2) How does the magnetic field structure, drive and interact with the plasma in the chromosphere and upper atmosphere? (3) How does the magnetic field destabilise the outer solar atmosphere and thus affect the interplanetary environment? (4) How do magnetic processes accelerate particles to high energies? New ground-breaking observations are needed to address these science questions. We suggest a suite of three instruments that far exceed current capabilities in terms of spatial resolution, light-gathering power, and polarimetric performance: (a) A large-aperture UV-to-IR telescope of the 1-3 m class aimed mainly to measure the magnetic field in the chromosphere by combining high spatial resolution and high sensitivity. (b) An extreme-UV-to-IR coronagraph that is designed to measure the large-scale magnetic field in the corona with an aperture of about 40 cm. (c) An extreme-UV imaging polarimeter based on a 30 cm telescope that combines high throughput in the extreme UV with polarimetry to connect the magnetic measurements of the other two instruments. Placed in a near-Earth orbit, the data downlink would be maximised, while a location at L4 or L5 would provide stereoscopic observations of the Sun in combination with Earth-based observatories. This mission to measure the magnetic field will finally unlock the driver of the dynamics in the outer solar atmosphere and thereby will greatly advance our understanding of the Sun and the heliosphere. Title: Vector Velocities Measurements with the Solar Orbiter SPICE Spectrometer Authors: Podladchikova, O.; Harra, L.; Barczynski, K.; Mandrini, C.; Auchère, F.; Berghmans, D.; Buchlin, E.; Dolla, L.; Mierla, M.; Parenti, S.; Rodriguez, L. Bibcode: 2021AAS...23831312P Altcode: The Solar Orbiter mission, with an orbit outside the Sun-Earth line and leaving the ecliptic plane, opens up opportunities for the combined analysis of measurements obtained by solar imagers and spectrometers. For the first time, different spectrometers will be located at wide angles to each other, allowing three-dimensional (3D) spectroscopy of the solar atmosphere. Here we develop a methodology to prepare for this kind of analysis, by using data from the Hinode mission and the Solar Dynamics Observatory, respectively. We employ solar rotation to simulate measurements of spectrometers with different views of the solar corona. The resulting data allow us to apply stereoscopic tie-pointing and triangulation techniques designed for the STEREO spacecraft pair, and to perform 3D analysis of the Doppler shifts of a quasi-stationary active region. Our approach allows the accurate reconstruction of 3D velocity vectors in plasma flows along "open" and "closed" magnetic loops. This technique will be applied to the actual situation of two spacecraft at different separations with spectrometers on board (the Solar Orbiter Spectral Imaging of the Coronal Environment versus the Interface Region Imaging Spectrograph (IRIS) and Hinode imaging spectrometer) and we summarise how these observations can be coordinated to assess vector velocity measurements. This 3D spectroscopy method will facilitate the understanding of the complex flows that take place throughout the solar atmosphere. Title: Mapping of Solar Magnetic Fields from the Photosphere to the Top of the Chromosphere with CLASP2 Authors: McKenzie, D.; Ishikawa, R.; Trujillo Bueno, J.; Auchere, F.; del Pino Aleman, T.; Okamoto, T.; Kano, R.; Song, D.; Yoshida, M.; Rachmeler, L.; Kobayashi, K.; Narukage, N.; Kubo, M.; Ishikawa, S.; Hara, H.; Suematsu, Y.; Sakao, T.; Bethge, C.; De Pontieu, B.; Vigil, G.; Winebarger, A.; Alsina Ballester, E.; Belluzzi, L.; Stepan, J.; Asensio Ramos, A.; Carlsson, M.; Leenaarts, J. Bibcode: 2021AAS...23810603M Altcode: Coronal heating, chromospheric heating, and the heating & acceleration of the solar wind, are well-known problems in solar physics. Additionally, knowledge of the magnetic energy that powers solar flares and coronal mass ejections, important drivers of space weather, is handicapped by imperfect determination of the magnetic field in the sun's atmosphere. Extrapolation of photospheric magnetic measurements into the corona is fraught with difficulties and uncertainties, partly due to the vastly different plasma beta between the photosphere and the corona. Better results in understanding the coronal magnetic field should be derived from measurements of the magnetic field in the chromosphere. To that end, we are pursuing quantitative determination of the magnetic field in the chromosphere, where plasma beta transitions from greater than unity to less than unity, via ultraviolet spectropolarimetry. The CLASP2 mission, flown on a sounding rocket in April 2019, succeeded in measuring all four Stokes polarization parameters in UV spectral lines formed by singly ionized Magnesium and neutral Manganese. Because these ions produce spectral lines under different conditions, CLASP2 thus was able to quantify the magnetic field properties at multiple heights in the chromosphere simultaneously, as shown in the recent paper by Ishikawa et al. In this presentation we will report the findings of CLASP2, demonstrating the variation of magnetic fields along a track on the solar surface and as a function of height in the chromosphere; and we will illustrate what is next for the CLASP missions and the demonstration of UV spectropolarimetry in the solar chromosphere. Title: Signatures of coronal hole substructure in the solar wind: combined Solar Orbiter remote sensing and in situ measurements Authors: Horbury, T. S.; Laker, R.; Rodriguez, L.; Steinvall, K.; Maksimovic, M.; Livi, S.; Berghmans, D.; Auchere, F.; Zhukov, A. N.; Khotyaintsev, Yu. V.; Woodham, L.; Matteini, L.; Stawarz, J.; Woolley, T.; Bale, S. D.; Rouillard, A.; O'Brien, H.; Evans, V.; Angelini, V.; Owen, C.; Solanki, S. K.; Nicula, B.; Muller, D.; Zouganelis, I. Bibcode: 2021arXiv210414960H Altcode: Context. The Sun's complex corona is the source of the solar wind and interplanetary magnetic field. While the large scale morphology is well understood, the impact of variations in coronal properties on the scale of a few degrees on properties of the interplanetary medium is not known. Solar Orbiter, carrying both remote sensing and in situ instruments into the inner solar system, is intended to make these connections better than ever before. Aims. We combine remote sensing and in situ measurements from Solar Orbiter's first perihelion at 0.5 AU to study the fine scale structure of the solar wind from the equatorward edge of a polar coronal hole with the aim of identifying characteristics of the corona which can explain the in situ variations. Methods. We use in situ measurements of the magnetic field, density and solar wind speed to identify structures on scales of hours at the spacecraft. Using Potential Field Source Surface mapping we estimate the source locations of the measured solar wind as a function of time and use EUI images to characterise these solar sources. Results. We identify small scale stream interactions in the solar wind with compressed magnetic field and density along with speed variations which are associated with corrugations in the edge of the coronal hole on scales of several degrees, demonstrating that fine scale coronal structure can directly influence solar wind properties and drive variations within individual streams. Conclusions. This early analysis already demonstrates the power of Solar Orbiter's combined remote sensing and in situ payload and shows that with future, closer perihelia it will be possible dramatically to improve our knowledge of the coronal sources of fine scale solar wind structure, which is important both for understanding the phenomena driving the solar wind and predicting its impacts at the Earth and elsewhere. Title: Mapping solar magnetic fields from the photosphere to the base of the corona Authors: Ishikawa, Ryohko; Bueno, Javier Trujillo; del Pino Alemán, Tanausú; Okamoto, Takenori J.; McKenzie, David E.; Auchère, Frédéric; Kano, Ryouhei; Song, Donguk; Yoshida, Masaki; Rachmeler, Laurel A.; Kobayashi, Ken; Hara, Hirohisa; Kubo, Masahito; Narukage, Noriyuki; Sakao, Taro; Shimizu, Toshifumi; Suematsu, Yoshinori; Bethge, Christian; De Pontieu, Bart; Dalda, Alberto Sainz; Vigil, Genevieve D.; Winebarger, Amy; Ballester, Ernest Alsina; Belluzzi, Luca; Štěpán, Jiří; Ramos, Andrés Asensio; Carlsson, Mats; Leenaarts, Jorrit Bibcode: 2021SciA....7.8406I Altcode: 2021arXiv210301583I Routine ultraviolet imaging of the Sun's upper atmosphere shows the spectacular manifestation of solar activity; yet we remain blind to its main driver, the magnetic field. Here we report unprecedented spectropolarimetric observations of an active region plage and its surrounding enhanced network, showing circular polarization in ultraviolet (Mg II $h$ & $k$ and Mn I) and visible (Fe I) lines. We infer the longitudinal magnetic field from the photosphere to the very upper chromosphere. At the top of the plage chromosphere the field strengths reach more than 300 gauss, strongly correlated with the Mg II $k$ line core intensity and the electron pressure. This unique mapping shows how the magnetic field couples the different atmospheric layers and reveals the magnetic origin of the heating in the plage chromosphere. Title: 20 years of ACE data: how superposed epoch analyses reveal generic features in interplanetary CME profiles Authors: Regnault, Florian; Dasso, Sergio; Auchere, Frederic; Demoulin, Pascal; Janvier, Miho; Strugarek, Antoine Bibcode: 2021cosp...43E1017R Altcode: Interplanetary Coronal Mass Ejections (ICMEs) result from solar flares occurring in our star's atmosphere. These large-scale magnetized structures propagate in the interplanetary medium where they can be probed by spacecraft. Depending on their speed, ICMEs may accumulate enough solar wind plasma to form a turbulent sheath ahead of them. They therefore consist of two main substructures : a sheath and a magnetic ejecta (ME). The magnetic ejecta is the main body of an ICME where the magnetic field is more intense and with less variance than that of the ambient solar wind. We present a statistical study using the superposed epoch analysis technique on a catalog of around 400 ICMEs where we consider the profiles of the physical parameters of the ICMEs (the magnetic field intensity, the speed, temperature, ...) seen at 1 AU by the ACE spacecraft. In particular, we investigate different possible classifications of ICMEs, for example based on their speeds, the phase of the solar cycle when they are detected, and the detection of an associated magnetic cloud (MCs, a subset of MEs with a clear rotation of the magnetic field as well as a low plasma temperature compared with the solar wind). We confirm that slow ICMEs have a more symmetric profile than fast ICMEs, therefore generalizing the work made on a sample of 44 ICMEs with clearly identified magnetic clouds by Masias-Meza et al. (2016). We also find that fast ICMEs show signs of compression in both their magnetic ejecta and in their sheath. Furthermore, we do not find any impact of the solar cycle on the generic features of ICMEs. However, more extreme events are observed during the active parts of the cycle, widening the distributions of all parameters. Finally, we find that ICMEs with or without a detected magnetic cloud show similar profiles, which confirms the hypothesis that both types of events correspond to similar ICMEs, and that the ones with no detected magnetic clouds may be observed when crossed sufficiently away from the flux rope core. Title: The Extreme ultraviolet imager onboard Solar Orbiter Authors: Berghmans, David; Harra, Louise K.; Zhukov, Andrei; Auchere, Frederic; Long, David; Schuehle, Udo; Rochus, Pierre Bibcode: 2021cosp...43E.949B Altcode: The Extreme Ultraviolet Imager (EUI) is part of the remote sensing instrument package of the ESA/NASA Solar Orbiter mission that will explore the inner heliosphere and observe the Sun from vantage points close to the Sun and out of the ecliptic. With EUI we aim to improve our understanding of the structure and dynamics of the solar atmosphere, globally as well as at high resolution, and from high solar latitude perspectives. The EUI consists of three telescopes, the Full Sun Imager (FSI) and two High Resolution Imagers (HRIs), which are optimised to image in Lyman-$\alpha$ and EUV (174 \AA, 304 \AA) to provide a coverage from chromosphere up to corona. The EUI instrument design will be reviewed, and its scientific objectives and plans will be discussed. Early results of the EUI commissioning will be presented. Title: Magnetic Imaging of the Outer Solar Atmosphere (MImOSA): Unlocking the driver of the dynamics in the upper solar atmosphere Authors: Peter, H.; Alsina Ballester, E.; Andretta, V.; Auchere, F.; Belluzzi, L.; Bemporad, A.; Berghmans, D.; Buchlin, E.; Calcines, A.; Chitta, L. P.; Dalmasse, K.; del Pino Aleman, T.; Feller, A.; Froment, C.; Harrison, R.; Janvier, M.; Matthews, S.; Parenti, S.; Przybylski, D.; Solanki, S. K.; Stepan, J.; Teriaca, L.; Trujillo Bueno, J. Bibcode: 2021arXiv210101566P Altcode: The magnetic activity of the Sun directly impacts the Earth and human life. Likewise, other stars will have an impact on the habitability of planets orbiting these host stars. The lack of information on the magnetic field in the higher atmospheric layers hampers our progress in understanding solar magnetic activity. Overcoming this limitation would allow us to address four paramount long-standing questions: (1) How does the magnetic field couple the different layers of the atmosphere, and how does it transport energy? (2) How does the magnetic field structure, drive and interact with the plasma in the chromosphere and upper atmosphere? (3) How does the magnetic field destabilise the outer solar atmosphere and thus affect the interplanetary environment? (4) How do magnetic processes accelerate particles to high energies? New ground-breaking observations are needed to address these science questions. We suggest a suite of three instruments that far exceed current capabilities in terms of spatial resolution, light-gathering power, and polarimetric performance: (a) A large-aperture UV-to-IR telescope of the 1-3 m class aimed mainly to measure the magnetic field in the chromosphere by combining high spatial resolution and high sensitivity. (b) An extreme-UV-to-IR coronagraph that is designed to measure the large-scale magnetic field in the corona with an aperture of about 40 cm. (c) An extreme-UV imaging polarimeter based on a 30 cm telescope that combines high throughput in the extreme UV with polarimetry to connect the magnetic measurements of the other two instruments. This mission to measure the magnetic field will unlock the driver of the dynamics in the outer solar atmosphere and thereby greatly advance our understanding of the Sun and the heliosphere. Title: Stereoscopic Measurements of Coronal Doppler Velocities aboard Solar Orbiter Authors: Podladchikova, Olena; Harra, Louise K.; Mandrini, Cristina H.; Rodriguez, Luciano; Parenti, Susanna; Dolla, Laurent; Buchlin, Eric; Auchere, Frederic; Mierla, Marilena; Barczynski, Krzysztof Bibcode: 2021cosp...43E.957P Altcode: The Solar Orbiter mission, whose orbit is outside the Sun-Earth line, opens up novel opportunities for the combined analysis of measurements by solar imagers and spectrometers. For the first time different spectrometers will be located at wide angles with each other allowing 3D spectroscopy in the solar atmosphere. In order to develop a methodology for these opportunities we make use of the Hinode EUV Imaging Spectrometer (EIS) and Atmospheric Imaging Assembly (AIA) on the Solar Dynamics Observatory (SDO) and by employing solar rotation we simulate the measurements of spectrometers that have different views of solar corona. The resulting data allows us to apply stereoscopic tie-pointing and triangulation techniques designed for SECCHI (Sun Earth Connection Coronal and Heliospheric Investigation) imaging suite on the STEREO (Solar Terrestrial Relations Observatory) spacecraft pair and perform three-dimensional analysis of Doppler shifts of quasi-stationary active region.We present a technique that allows the accurate reconstruction of the 3D velocity vector in plasma flows along open and closed magnetic loops. This technique will be applied to the real situation of two spacecraft at different separations with spectrometers onboard. This will include the Solar Orbiter Spectral Imaging of the Coronal Environment (SPICE), the Solar Orbiter Extreme Ultraviolet Imager (EUI), the Interface Region Imaging Spectrograph (IRIS) and Hinode EIS spectrometers and we summarise how these can be coordinated. This 3D spectroscopy is a new research domain that will aid the understanding of the complex flows that take place throughout the solar atmosphere. Title: The MDOR/PDOR on-line module for MISO, the planning software of Solar Orbiter instruments Authors: Volpicelli, Cosimo; Landini, Federico; Pancrazzi, Maurizio; Straus, Thomas; Susino, Roberto; Nicolini, Gianalfredo; Sasso, Clementina; Fabi, Michele; De Leo, Yara; Casini, Chiara; Naletto, Giampiero; Nicolosi, Piergiorgio; Spadaro, Daniele; Andretta, Vincenzo; Antonucci, Ester; Fineschi, Silvano; Da Deppo, Vania; Zuppella, Paola; Frassetto, Fabio; Slemer, Alessandra; Mercier, Claude; Kouliche, Dimitri; Caminade, Stephane; Picard, David; Buchlin, Eric; Auchère, Frédéric; Romoli, Marco Bibcode: 2020SPIE11452E..0SV Altcode: Solar Orbiter is a solar mission that will approach the Sun down to a minimum perihelion of 0.28 AU and will increase its orbit inclination with respect to the ecliptic up to a maximum angle of 34 deg. For imagers aboard Solar Orbiter there will be three 10-days remote sensing windows per orbit. Observations shall be carefully planned at least 6 months in advance. The Multi Instrument Sequence Organizer (MISO) is a web based platform developed by the SPICE group and made available to support Solar Orbiter instruments teams in planning observations by assembling Mission Database sequences. Metis is the UV and visible light coronagraph aboard Solar Orbiter. Metis is a complex instrument characterized by a rich variety of observing modes, which required a careful commissioning activity and will need support for potential maintenance operations throughout the mission. In order to support commissioning and maintenance activities, the Metis team developed a PDOR (Payload Direct Operation Request) and MDOR (Memory Direct Operation Request) module integrated in MISO and made available to all Solar Orbiter instruments. An effort was made in order to interpret the coding philosophy of the main project and to make the additional module as homogeneous as possible both to the web interface and to the algorithm logic, while integrating characteristics which are peculiar to PDORs and MDORs. An user friendly web based interface allows the operator to build the operation request and to successively modify or integrate it with further or alternative information. In the present work we describe the PDOR/MDOR module for MISO by addressing its logic and main characteristics. Title: Relative coronal abundance diagnostics with Solar Orbiter/SPICE Authors: Zambrana Prado, N.; Buchlin, E.; Peter, H.; Young, P. R.; Auchere, F.; Carlsson, M.; Fludra, A.; Hassler, D.; Aznar Cuadrado, R.; Caminade, S.; Caldwell, M.; DeForest, C.; Fredvik, T.; Harra, L.; Janvier, M.; Kucera, T. A.; Giunta, A. S.; Grundy, T.; Müller, D.; Parenti, S.; Schmutz, W. K.; Schühle, U.; Sidher, S.; Teriaca, L.; Thompson, W. T.; Williams, D. Bibcode: 2020AGUFMSH038..09Z Altcode: Linking solar activity on the surface and in the corona to the inner heliosphere is one of Solar Orbiter's main goals. Its UV spectrometer SPICE (SPectral Imaging of the Coronal Environment) will provide relative abundance measurements which will be key in this quest as different structures on the Sun have different abundances as a consequence of the FIP (First Ionization Potential) effect. Solar Orbiter's unique combination of remote sensing and in-situ instruments coupled with observation from other missions such as Parker Solar Probe will allow us to compare in-situ and remote sensing composition data. With the addition of modeling, these new results will allow us to trace back the source of heliospheric plasma. As high telemetry will not always be available with SPICE, we have developed a method for measuring relative abundances that is both telemetry efficient and reliable. Unlike methods based on Differential Emission Measure (DEM) inversion, the Linear Combination Ratio (LCR) method does not require a large number of spectral lines. This new method is based on linear combinations of UV spectral lines. The coefficients of the combinations are optimized such that the ratio of two linear combinations of radiances would yield the relative abundance of two elements. We present some abundance diagnostics tested on different combinations of spectral lines observable by SPICE. Title: Dynamics and thermal structure in the quiet Sun seen by SPICE Authors: Peter, H.; Aznar Cuadrado, R.; Schühle, U.; Teriaca, L.; Auchere, F.; Carlsson, M.; Fludra, A.; Hassler, D.; Buchlin, E.; Caminade, S.; Caldwell, M.; DeForest, C.; Fredvik, T.; Harra, L. K.; Janvier, M.; Kucera, T. A.; Giunta, A. S.; Grundy, T.; Müller, D.; Parenti, S.; Schmutz, W. K.; Sidher, S.; Thompson, W. T.; Williams, D.; Young, P. R. Bibcode: 2020AGUFMSH038..03P Altcode: We will present some of the early data of the Spectral Imaging of the Coronal Environment (SPICE) instrument on Solar Orbiter. One of the unique features of SPICE is its capability to record a wide range of wavelengths in the extreme UV with the possibility to record spectral lines giving access to a continuous plasma temperature range from 10.000 K to well above 1 MK. The data taken so far were for commissioning purposes and they can be used for a preliminary evaluation of the science performance of the instrument. Here we will concentrate on sample spectra covering the whole wavelength region and on the early raster maps acquired in bright lines in the quiet Sun close to disk center. Looking at different quiet Sun features we investigate the thermal structure of the atmosphere and flow structures. For this we apply fits to the spectral profiles and check the performance in terms of Doppler shifts and line widths to retrieve the structure of the network in terms of dynamics. While the amount of data available so far is limited, we will have a first look on how quiet Sun plasma responds to heating events. For this, we will compare spectral lines forming at different temperatures recorded at strictly the same time. Title: First Results From SPICE EUV Spectrometer on Solar Orbiter Authors: Fludra, A.; Caldwell, M.; Giunta, A. S.; Grundy, T.; Guest, S.; Sidher, S.; Auchere, F.; Carlsson, M.; Hassler, D.; Peter, H.; Aznar Cuadrado, R.; Buchlin, E.; Caminade, S.; DeForest, C.; Fredvik, T.; Harra, L. K.; Janvier, M.; Kucera, T. A.; Leeks, S.; Mueller, D.; Parenti, S.; Schmutz, W. K.; Schühle, U.; Teriaca, L.; Thompson, W. T.; Tustain, S.; Williams, D.; Young, P. R. Bibcode: 2020AGUFMSH038..02F Altcode: SPICE (Spectral Imaging of Coronal Environment) is one of the remote sensing instruments onboard Solar Orbiter. It is an EUV imaging spectrometer observing the Sun in two wavelength bands: 69.6-79.4 nm and 96.6-105.1 nm. SPICE is capable of recording full spectra in these bands with exposures as short as 1s. SPICE is the only Solar Orbiter instrument that can measure EUV spectra from the disk and low corona of the Sun and record all spectral lines simultaneously. SPICE uses one of three narrow slits, 2"x11', 4''x11', 6''x11', or a wide slit 30''x14'. The primary mirror can be scanned in a direction perpendicular to the slit, allowing raster images of up to 16' in size.

We present an overview of the first SPICE data taken on several days during the instrument commissioning carried out by the RAL Space team between 2020 April 21 and 2020 June 14. We also include results from SPICE observations at the first Solar Orbiter perihelion at 0.52AU, taken between June 16-21st. We give examples of full spectra from the quiet Sun near disk centre and provide a list of key spectral lines emitted in a range of temperatures between 10,000 K and over 1 million K, from neutral hydrogen and ions of carbon, oxygen, nitrogen, neon, sulphur and magnesium. We show examples of first raster images in several strong lines, obtained with different slits and a range of exposure times between 5s and 180s. We describe the temperature coverage and density diagnostics, determination of plasma flows, and discuss possible applications to studies of the elemental abundances in the corona. We also show the first off-limb measurements with SPICE, as obtained when the spacecraft pointed at the limb. Title: The Solar-C (EUVST) mission: the latest status Authors: Shimizu, Toshifumi; Imada, Shinsuke; Kawate, Tomoko; Suematsu, Yoshinori; Hara, Hirohisa; Tsuzuki, Toshihiro; Katsukawa, Yukio; Kubo, Masahito; Ishikawa, Ryoko; Watanabe, Tetsuya; Toriumi, Shin; Ichimoto, Kiyoshi; Nagata, Shin'ichi; Hasegawa, Takahiro; Yokoyama, Takaaki; Watanabe, Kyoko; Tsuno, Katsuhiko; Korendyke, Clarence M.; Warren, Harry; De Pontieu, Bart; Boerner, Paul; Solanki, Sami K.; Teriaca, Luca; Schuehle, Udo; Matthews, Sarah; Long, David; Thomas, William; Hancock, Barry; Reid, Hamish; Fludra, Andrzej; Auchère, Frederic; Andretta, Vincenzo; Naletto, Giampiero; Poletto, Luca; Harra, Louise Bibcode: 2020SPIE11444E..0NS Altcode: Solar-C (EUVST) is the next Japanese solar physics mission to be developed with significant contributions from US and European countries. The mission carries an EUV imaging spectrometer with slit-jaw imaging system called EUVST (EUV High-Throughput Spectroscopic Telescope) as the mission payload, to take a fundamental step towards answering how the plasma universe is created and evolves and how the Sun influences the Earth and other planets in our solar system. In April 2020, ISAS (Institute of Space and Astronautical Science) of JAXA (Japan Aerospace Exploration Agency) has made the final down-selection for this mission as the 4th in the series of competitively chosen M-class mission to be launched with an Epsilon launch vehicle in mid 2020s. NASA (National Aeronautics and Space Administration) has selected this mission concept for Phase A concept study in September 2019 and is in the process leading to final selection. For European countries, the team has (or is in the process of confirming) confirmed endorsement for hardware contributions to the EUVST from the national agencies. A recent update to the mission instrumentation is to add a UV spectral irradiance monitor capability for EUVST calibration and scientific purpose. This presentation provides the latest status of the mission with an overall description of the mission concept emphasizing on key roles of the mission in heliophysics research from mid 2020s. Title: Observation of Smallest Ever Detected Brightening Events with the Solar Orbiter EUI HRI-EUV Imager Authors: Parenti, S.; Berghmans, D.; Buchlin, E.; Teriaca, L.; Auchere, F.; Harra, L.; Long, D.; Rochus, P. L.; Schühle, U.; Aznar Cuadrado, R.; Gissot, S.; Kraaikamp, E.; Smith, P.; Stegen, K.; Verbeeck, C. Bibcode: 2020AGUFMSH038..01P Altcode: The Extreme Ultraviolet Imager (EUI) suite on board Solar Orbiter acquired its first images in May 2020. The passband of the 17.4 nm High Resolution Imager (HRI-EUV) is dominated by emission lines of Fe IX and Fe X, that is the 1 million degree solar corona. The solar atmosphere at this temperature is dynamic at all scales, down to the highest spatial resolution available from instruments priori to Solar Orbiter. During the Commissioning phase, HRI-EUV acquired several high temporal resolution (a few seconds) sequences at quiet Sun regions at disk center. The instrument revealed a multitude of brightenings at the smallest-ever detectable spatial scales which, at that time, was about 400 km (two pixels). These events appear to be present everywhere all the time. We present the first results of the analysis of these sequences with the aim of understanding the role of these small scale events in the heating of the solar corona. Title: Stereoscopic Measurements of Coronal Doppler Velocities Authors: Podladchikova, O.; Harra, L. K.; Barczynski, K.; Mandrini, C. H.; Auchere, F.; Buchlin, E.; Dolla, L.; Mierla, M.; Rodriguez, L. Bibcode: 2020AGUFMSH038..07P Altcode: The Solar Orbiter mission, whose orbit is outside the Sun-Earth line, opens up novel opportunities for the combined analysis of measurements by solar imagers and spectrometers. For the first time different spectrometers will be located at wide angles with each other allowing 3D spectroscopy in the solar atmosphere. In order to develop a methodology for these opportunities we make use of the Hinode EUV Imaging Spectrometer (EIS) and Atmospheric Imaging Assembly (AIA) on the Solar Dynamics Observatory (SDO) and by employing solar rotation we simulate the measurements of two spectrometers that have different views of solar corona. The resulting data allows us to apply stereoscopic tie-pointing and triangulation techniques designed for SECCHI (Sun Earth Connection Coronal and Heliospheric Investigation) imaging suite on the STEREO (Solar Terrestrial Relations Observatory) spacecraft pair and perform three-dimensional analysis of Doppler shifts of quasi-stationary active region. We present a technique that allows the accurate reconstruction of the 3D velocity vector in plasma flows along open and closed magnetic loops. This technique will be applied to the real situation of two spacecraft at different separations with spectrometers onboard. This will include the Solar Orbiter Spectral Imaging of the Coronal Environment (SPICE), the Solar Orbiter Extreme Ultraviolet Imager (EUI),the Interface Region Imaging Spectrograph (IRIS) and Hinode EIS spectrometers and we summarise how these can be coordinated. This 3D spectroscopy is a new research domain that will aid the understanding of the complex flows that take place throughout the solar atmosphere. Title: Optical design of the Chromospheric LAyer Spectro-Polarimeter (CLASP2) Authors: Tsuzuki, Toshihiro; Ishikawa, Ryohko; Kano, Ryouhei; Narukage, Noriyuki; Song, Donguk; Yoshida, Masaki; Uraguchi, Fumihiro; Okamoto, Takenori J.; McKenzie, David; Kobayashi, Ken; Rachmeler, Laurel; Auchere, Frederic; Trujillo Bueno, Javier Bibcode: 2020SPIE11444E..6WT Altcode: Chromospheric LAyer Spectro-Polarimeter (CLASP2) was a sounding rocket experiment, which is a follow-up mission to the Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP1) in 2015. To measure the magnetic fields in the upper solar atmosphere in a highly quantitative manner, CLASP2 changes the target wavelengths from the hydrogen Ly-α line (121.567 nm) to Mg II lines near 280 nm. We reused the main structure and most of the optical components in the CLASP1 instrument, which reduced the turnaround time and cost. We added a magnifying optical system to maintain the wavelength resolution, even at the longer wavelength of CLASP2. Here, we describe the optical design and performance of the CLASP2 instrument. Title: Calibrating optical distortions in the Solar Orbiter SPICE spectrograph Authors: Thompson, W. T.; Schühle, U.; Young, P. R.; Auchere, F.; Carlsson, M.; Fludra, A.; Hassler, D.; Peter, H.; Aznar Cuadrado, R.; Buchlin, E.; Caldwell, M.; DeForest, C.; Fredvik, T.; Harra, L. K.; Janvier, M.; Kucera, T. A.; Giunta, A. S.; Grundy, T.; Müller, D.; Parenti, S.; Caminade, S.; Schmutz, W. K.; Teriaca, L.; Williams, D.; Sidher, S. Bibcode: 2020AGUFMSH0360029T Altcode: The Spectral Imaging of the Coronal Environment (SPICE) instrument on Solar Orbiter is a high-resolution imaging spectrometer operating at extreme ultraviolet (EUV) wavelengths from 70.4-79.0 nm and 97.3-104.9 nm. A single-mirror off-axis paraboloid focuses the solar image onto the entrance slit of the spectrometer section. A Toroidal Variable Line Space (TVLS) grating images the entrance slit onto a pair of MCP-intensified APS detectors. Ray-tracing analysis prior to launch showed that the instrument was subject to a number of small image distortions which need to be corrected in the final data product. We compare the ray tracing results with measurements made in flight. Co-alignment with other telescopes on Solar Orbiter will also be examined. Title: First results from the EUI and SPICE observations of Alpha Leo near Solar Orbiter first perihelion Authors: Buchlin, E.; Teriaca, L.; Giunta, A. S.; Grundy, T.; Andretta, V.; Auchere, F.; Peter, H.; Berghmans, D.; Carlsson, M.; Fludra, A.; Harra, L.; Hassler, D.; Long, D.; Rochus, P. L.; Schühle, U.; Aznar Cuadrado, R.; Caldwell, M.; Caminade, S.; DeForest, C.; Fredvik, T.; Gissot, S.; Heerlein, K.; Janvier, M.; Kraaikamp, E.; Kucera, T. A.; Müller, D.; Parenti, S.; Schmutz, W. K.; Sidher, S.; Smith, P.; Stegen, K.; Thompson, W. T.; Verbeeck, C.; Williams, D.; Young, P. R. Bibcode: 2020AGUFMSH0360024B Altcode: On June 16th 2020 Solar Orbiter made a dedicated observing campaign where the spacecraft pointed to the solar limb to allow some of the high resolution instruments to observe the ingress (at the east limb) and later the egress (west limb) of the occultation of the star Alpha Leonis by the solar disk. The star was chosen because its luminosity and early spectral type ensure high and stable flux at wavelengths between 100 and 122 nanometers, a range observed by the High Resolution EUI Lyman alpha telescope (HRI-LYA) and by the long wavelength channel of the SPICE spectrograph. Star observations, when feasible, allow to gather a great deal of information on the instrument performances, such as the radiometric performance and the instrument optical point spread function (PSF).

We report here the first results from the above campaign for the two instruments. Title: Solar Orbiter: connecting remote sensing and in situ measurements Authors: Horbury, T. S.; Auchere, F.; Antonucci, E.; Berghmans, D.; Bruno, R.; Carlsson, M.; del Toro Iniesta, J. C.; Fludra, A.; Harra, L.; Hassler, D.; Heinzel, P.; Howard, R. A.; Krucker, S.; Livi, S. A.; Long, D.; Louarn, P.; Maksimovic, M.; Mueller, D.; Owen, C. J.; Peter, H.; Rochus, P. L.; Rodriguez-Pacheco, J.; Romoli, M.; Schühle, U.; Solanki, S. K.; Teriaca, L.; Wimmer-Schweingruber, R. F.; Zouganelis, Y.; Laker, R. Bibcode: 2020AGUFMSH038..10H Altcode: A key science goal of the Solar Orbiter mission is to make connections between phenomena on the Sun and their manifestations in interplanetary space. To that end, the spacecraft carries a carefully tailored payload of six remote sensing instruments and four making in situ measurements. During June 2020, while the spacecraft was around 0.5 AU from the Sun, the remote sensing instruments operated for several days. While this was primarily an engineering activity, the resulting observations provided outstanding measurements and represent the ideal first opportunity to investigate the potential for making connections between the remote sensing and in situ payloads on Solar Orbiter.

We present a preliminary analysis of the available remote sensing and in situ observations, showing how connections can be made, and discuss the potential for further, more precise mapping to be performed as the mission progresses. Title: First Images and Initial In-Flight Performance of the Extreme Ultraviolet Imager On-Board Solar Orbiter. Authors: Auchere, F.; Gissot, S.; Teriaca, L.; Berghmans, D.; Harra, L.; Long, D.; Rochus, P. L.; Smith, P.; Schühle, U.; Stegen, K.; Aznar Cuadrado, R.; Heerlein, K.; Kraaikamp, E.; Verbeeck, C. Bibcode: 2020AGUFMSH0360025A Altcode: The Extreme Ultraviolet Imager (EUI) on board Solar Orbiter is composed of two High Resolution Imagers working at 121.6 (HRI-LYA, H I, chromosphere) and 17.4 nm (HRI-EUV, Fe IX/X, corona) and one dual-band Full Sun Imager (FSI) working at 30.4 nm (He II, transition region) and 17.4 nm (Fe IX/X, corona). During the commissioning period following the launch of Solar Orbiter and two and a half months of outgassing, EUI acquired its first solar images on May 12th, 2020 at about 0.67 AU. Most of the capabilities of the instrument have been tested during the following weeks, which revealed excellent overall performance. HRI-EUV already provided images with an angular resolution equivalent to ~0.6" (2 pixels) at 1 A.U. HRI-LYA will routinely provide images of the Sun at Lyman alpha, which have been otherwise relatively rare, with sub-second cadence capability. FSI will provide context for connection science but it will also explore regions of the corona never imaged before at EUV wavelengths, owing to its 3.8° field of view. EUI uses a complex on-board image processing system including advanced image compression and event detection algorithms. In particular, commissioning tests confirm the good performance of the compression, which is critical given the limited total telemetry volume imposed by the mission profile. In this paper, we present the main characteristics of the first images taken in each channel and we provide an initial assessment of the in-flight performance. Title: First results from combined EUI and SPICE observations of Lyman lines of Hydrogen and He II Authors: Teriaca, L.; Aznar Cuadrado, R.; Giunta, A. S.; Grundy, T.; Parenti, S.; Auchere, F.; Vial, J. C.; Fludra, A.; Berghmans, D.; Carlsson, M.; Harra, L.; Hassler, D.; Long, D.; Peter, H.; Rochus, P. L.; Schühle, U.; Buchlin, E.; Caldwell, M.; Caminade, S.; DeForest, C.; Fredvik, T.; Gissot, S.; Heerlein, K.; Janvier, M.; Kraaikamp, E.; Kucera, T. A.; Mueller, D.; Schmutz, W. K.; Sidher, S.; Smith, P.; Stegen, K.; Thompson, W. T.; Verbeeck, C.; Williams, D.; Young, P. R. Bibcode: 2020AGUFMSH0360003T Altcode: The Solar Orbiter spacecraft carries a powerful set of remote sensing instruments that allow studying the solar atmosphere with unprecedented diagnostic capabilities. Many such diagnostics require the simultaneous usage of more than one instrument. One example of that is the capability, for the first time, to obtain (near) simultaneous spatially resolved observations of the emission from the first three lines of the Lyman series of hydrogen and of He II Lyman alpha. In fact, the SPectral Imaging of the Coronal Environment (SPICE) spectrometer can observe the Lyman beta and gamma lines in its long wavelength (SPICE-LW) channel, the High Resolution Lyman Alpha (HRI-LYA) telescope of the Extreme Ultraviolet Imager (EUI) acquires narrow band images in the Lyman alpha line while the Full Disk Imager (FSI) of EUI can take images dominated by the Lyman alpha line of ionized Helium at 30.4 nm (FSI-304). Being hydrogen and helium the main components of our star, these very bright transitions play an important role in the energy budget of the outer atmosphere via radiative losses and the measurement of their profiles and radiance ratios is a fundamental constraint to any comprehensive modelization effort of the upper solar chromosphere and transition region. Additionally, monitoring their average ratios can serve as a check out for the relative radiometric performance of the two instruments throughout the mission. Although the engineering data acquired so far are far from ideal in terms of time simultaneity (often only within about 1 h) and line coverage (often only Lyman beta was acquired by SPICE and not always near simultaneous images from all three telescopes are available) the analysis we present here still offers a great opportunity to have a first look at the potential of this diagnostic from the two instruments. In fact, we have identified a series of datasets obtained at disk center and at various positions at the solar limb that allow studying the Lyman alpha to beta radiance ratio and their relation to He II 30.4 as a function of the position on the Sun (disk center versus limb and quiet Sun versus coronal holes). Title: Very high-resolution observations of the solar atmosphere in H I Lyman alpha and Fe IX-X at 17.4 nm as seen by EUI aboard Solar Orbiter Authors: Aznar Cuadrado, R.; Berghmans, D.; Teriaca, L.; Gissot, S.; Schühle, U.; Auchere, F.; Harra, L.; Long, D.; Rochus, P. L.; Heerlein, K.; Kraaikamp, E.; Smith, P.; Stegen, K.; Verbeeck, C. Bibcode: 2020AGUFMSH0360026A Altcode: The Extreme Ultraviolet Imager (EUI) aboard Solar Orbiter consists of three telescopes, the Full Sun Imager (FSI) and two High Resolution Imagers (HRIs). The two HRI telescopes provide images of the base of the corona, near to the chromosphere, and of the 1 million K corona. In fact, the HRI-EUV telescope operates around 17.4 nm to obtain images dominated by emission from lines generated from Fe-IX and X ions, formed at about 1 MK, while the HRI-LYA telescope provides narrow band images dominated by the H I Lyman alpha line at 121.6 nm, formed in the upper chromosphere/lower transition region of the solar atmosphere around 20,000 K. Thus, the two imagers provide a powerful diagnostics of the solar structural organization, in terms of loop hierarchies and connectivity. Here we present an analysis of the first two near-simultaneous (within 15s) high-resolution images of the solar quiet atmosphere obtained near disk center by the two high-resolution telescopes on May 30th 2020, during the commissioning phase of the mission , when Solar Orbiter was at about 0.56 AU from the Sun. Title: A sensitivity analysis of the updated optical design for EUVST on the Solar-C mission Authors: Kawate, Tomoko; Tsuzuki, Toshihiro; Shimizu, Toshifumi; Imada, Shinsuke; Katsukawa, Yukio; Hara, Hirohisa; Suematsu, Yoshinori; Ichimoto, Kiyoshi; Hattori, Tomoya; Narasaki, Shota; Warren, Harry P.; Teriaca, Luca; Korendyke, Clarence M.; Brown, Charles M.; Auchere, Frederic Bibcode: 2020SPIE11444E..3JK Altcode: The EUV high-throughput spectroscopic telescope (EUVST) onboard the Solar-C mission has the high spatial (0.4'') resolution over a wide wavelength range in the vacuum ultraviolet. To achieve high spatial resolution under a design constraint given by the JAXA Epsilon launch vehicle, we further update the optical design to secure margins needed to realize 0.4'' spatial resolution over a field of view of 100''×100''. To estimate the error budgets of spatial and spectral resolutions due to installation and fabrication errors, we perform a sensitivity analysis for the position and orientation of each optical element and for the grating parameters by ray tracing with the Zemax software. We obtain point spread functions (PSF) for rays from 9 fields and at 9 wavelengths on each detector by changing each parameter slightly. A full width at half maximum (FWHM) of the PSF is derived at each field and wavelength position as a function of the perturbation of each optical parameter. Assuming a mount system of each optical element and an error of each optical parameter, we estimate spatial and spectral resolutions by taking installation and fabrication errors into account. The results of the sensitivity analysis suggest that budgets of the total of optical design and the assembly errors account for 15% and 5.8% of our budgets of the spatial resolution in the long wavelength and short wavelength bands, respectively. On the other hand, the grating fabrication errors give a large degradation of spatial and spectral resolutions, and investigations of compensators are needed to relax the fabrication tolerance of the grating surface parameters. Title: 20 Years of ACE Data: How Superposed Epoch Analyses Reveal Generic Features in Interplanetary CME Profiles Authors: Regnault, F.; Janvier, M.; Démoulin, P.; Auchère, F.; Strugarek, A.; Dasso, S.; Noûs, C. Bibcode: 2020JGRA..12528150R Altcode: 2020arXiv201105050R Interplanetary coronal mass ejections (ICMEs) are magnetic structures propagating from the Sun's corona to the interplanetary medium. With over 20 years of observations at the L1 libration point, ACE offers hundreds of ICMEs detected at different times during several solar cycles and with different features such as the propagation speed. We investigate a revisited catalog of more than 400 ICMEs using the superposed epoch method on the mean, median, and the most probable values of the distribution of magnetic and plasma parameters. We also investigate the effects of the speed of ICMEs relative to the solar wind, the solar cycle, and the existence of a magnetic cloud on the generic ICME profile. We find that fast-propagating ICMEs (relatively to the solar wind in front) still show signs of compression at 1 au, as seen by the compressed sheath and the asymmetric profile of the magnetic field. While the solar cycle evolution does not impact the generic features of ICMEs, there are more extreme events during the active part of the cycle, widening the distributions of all parameters. Finally, we find that ICMEs with or without a detected magnetic cloud show similar profiles, which confirms the hypothesis that ICMEs with no detected magnetic clouds are crossed further away from the flux rope core. Such a study provides a generic understanding of processes that shape the overall features of ICMEs in the solar wind and can be extended with future missions at different locations in the solar system. Title: Coordination within the remote sensing payload on the Solar Orbiter mission Authors: Auchère, F.; Andretta, V.; Antonucci, E.; Bach, N.; Battaglia, M.; Bemporad, A.; Berghmans, D.; Buchlin, E.; Caminade, S.; Carlsson, M.; Carlyle, J.; Cerullo, J. J.; Chamberlin, P. C.; Colaninno, R. C.; Davila, J. M.; De Groof, A.; Etesi, L.; Fahmy, S.; Fineschi, S.; Fludra, A.; Gilbert, H. R.; Giunta, A.; Grundy, T.; Haberreiter, M.; Harra, L. K.; Hassler, D. M.; Hirzberger, J.; Howard, R. A.; Hurford, G.; Kleint, L.; Kolleck, M.; Krucker, S.; Lagg, A.; Landini, F.; Long, D. M.; Lefort, J.; Lodiot, S.; Mampaey, B.; Maloney, S.; Marliani, F.; Martinez-Pillet, V.; McMullin, D. R.; Müller, D.; Nicolini, G.; Orozco Suarez, D.; Pacros, A.; Pancrazzi, M.; Parenti, S.; Peter, H.; Philippon, A.; Plunkett, S.; Rich, N.; Rochus, P.; Rouillard, A.; Romoli, M.; Sanchez, L.; Schühle, U.; Sidher, S.; Solanki, S. K.; Spadaro, D.; St Cyr, O. C.; Straus, T.; Tanco, I.; Teriaca, L.; Thompson, W. T.; del Toro Iniesta, J. C.; Verbeeck, C.; Vourlidas, A.; Watson, C.; Wiegelmann, T.; Williams, D.; Woch, J.; Zhukov, A. N.; Zouganelis, I. Bibcode: 2020A&A...642A...6A Altcode: Context. To meet the scientific objectives of the mission, the Solar Orbiter spacecraft carries a suite of in-situ (IS) and remote sensing (RS) instruments designed for joint operations with inter-instrument communication capabilities. Indeed, previous missions have shown that the Sun (imaged by the RS instruments) and the heliosphere (mainly sampled by the IS instruments) should be considered as an integrated system rather than separate entities. Many of the advances expected from Solar Orbiter rely on this synergistic approach between IS and RS measurements.
Aims: Many aspects of hardware development, integration, testing, and operations are common to two or more RS instruments. In this paper, we describe the coordination effort initiated from the early mission phases by the Remote Sensing Working Group. We review the scientific goals and challenges, and give an overview of the technical solutions devised to successfully operate these instruments together.
Methods: A major constraint for the RS instruments is the limited telemetry (TM) bandwidth of the Solar Orbiter deep-space mission compared to missions in Earth orbit. Hence, many of the strategies developed to maximise the scientific return from these instruments revolve around the optimisation of TM usage, relying for example on onboard autonomy for data processing, compression, and selection for downlink. The planning process itself has been optimised to alleviate the dynamic nature of the targets, and an inter-instrument communication scheme has been implemented which can be used to autonomously alter the observing modes. We also outline the plans for in-flight cross-calibration, which will be essential to the joint data reduction and analysis.
Results: The RS instrument package on Solar Orbiter will carry out comprehensive measurements from the solar interior to the inner heliosphere. Thanks to the close coordination between the instrument teams and the European Space Agency, several challenges specific to the RS suite were identified and addressed in a timely manner. Title: The Solar Orbiter Science Activity Plan. Translating solar and heliospheric physics questions into action Authors: Zouganelis, I.; De Groof, A.; Walsh, A. P.; Williams, D. R.; Müller, D.; St Cyr, O. C.; Auchère, F.; Berghmans, D.; Fludra, A.; Horbury, T. S.; Howard, R. A.; Krucker, S.; Maksimovic, M.; Owen, C. J.; Rodríguez-Pacheco, J.; Romoli, M.; Solanki, S. K.; Watson, C.; Sanchez, L.; Lefort, J.; Osuna, P.; Gilbert, H. R.; Nieves-Chinchilla, T.; Abbo, L.; Alexandrova, O.; Anastasiadis, A.; Andretta, V.; Antonucci, E.; Appourchaux, T.; Aran, A.; Arge, C. N.; Aulanier, G.; Baker, D.; Bale, S. D.; Battaglia, M.; Bellot Rubio, L.; Bemporad, A.; Berthomier, M.; Bocchialini, K.; Bonnin, X.; Brun, A. S.; Bruno, R.; Buchlin, E.; Büchner, J.; Bucik, R.; Carcaboso, F.; Carr, R.; Carrasco-Blázquez, I.; Cecconi, B.; Cernuda Cangas, I.; Chen, C. H. K.; Chitta, L. P.; Chust, T.; Dalmasse, K.; D'Amicis, R.; Da Deppo, V.; De Marco, R.; Dolei, S.; Dolla, L.; Dudok de Wit, T.; van Driel-Gesztelyi, L.; Eastwood, J. P.; Espinosa Lara, F.; Etesi, L.; Fedorov, A.; Félix-Redondo, F.; Fineschi, S.; Fleck, B.; Fontaine, D.; Fox, N. J.; Gandorfer, A.; Génot, V.; Georgoulis, M. K.; Gissot, S.; Giunta, A.; Gizon, L.; Gómez-Herrero, R.; Gontikakis, C.; Graham, G.; Green, L.; Grundy, T.; Haberreiter, M.; Harra, L. K.; Hassler, D. M.; Hirzberger, J.; Ho, G. C.; Hurford, G.; Innes, D.; Issautier, K.; James, A. W.; Janitzek, N.; Janvier, M.; Jeffrey, N.; Jenkins, J.; Khotyaintsev, Y.; Klein, K. -L.; Kontar, E. P.; Kontogiannis, I.; Krafft, C.; Krasnoselskikh, V.; Kretzschmar, M.; Labrosse, N.; Lagg, A.; Landini, F.; Lavraud, B.; Leon, I.; Lepri, S. T.; Lewis, G. R.; Liewer, P.; Linker, J.; Livi, S.; Long, D. M.; Louarn, P.; Malandraki, O.; Maloney, S.; Martinez-Pillet, V.; Martinovic, M.; Masson, A.; Matthews, S.; Matteini, L.; Meyer-Vernet, N.; Moraitis, K.; Morton, R. J.; Musset, S.; Nicolaou, G.; Nindos, A.; O'Brien, H.; Orozco Suarez, D.; Owens, M.; Pancrazzi, M.; Papaioannou, A.; Parenti, S.; Pariat, E.; Patsourakos, S.; Perrone, D.; Peter, H.; Pinto, R. F.; Plainaki, C.; Plettemeier, D.; Plunkett, S. P.; Raines, J. M.; Raouafi, N.; Reid, H.; Retino, A.; Rezeau, L.; Rochus, P.; Rodriguez, L.; Rodriguez-Garcia, L.; Roth, M.; Rouillard, A. P.; Sahraoui, F.; Sasso, C.; Schou, J.; Schühle, U.; Sorriso-Valvo, L.; Soucek, J.; Spadaro, D.; Stangalini, M.; Stansby, D.; Steller, M.; Strugarek, A.; Štverák, Š.; Susino, R.; Telloni, D.; Terasa, C.; Teriaca, L.; Toledo-Redondo, S.; del Toro Iniesta, J. C.; Tsiropoula, G.; Tsounis, A.; Tziotziou, K.; Valentini, F.; Vaivads, A.; Vecchio, A.; Velli, M.; Verbeeck, C.; Verdini, A.; Verscharen, D.; Vilmer, N.; Vourlidas, A.; Wicks, R.; Wimmer-Schweingruber, R. F.; Wiegelmann, T.; Young, P. R.; Zhukov, A. N. Bibcode: 2020A&A...642A...3Z Altcode: 2020arXiv200910772Z Solar Orbiter is the first space mission observing the solar plasma both in situ and remotely, from a close distance, in and out of the ecliptic. The ultimate goal is to understand how the Sun produces and controls the heliosphere, filling the Solar System and driving the planetary environments. With six remote-sensing and four in-situ instrument suites, the coordination and planning of the operations are essential to address the following four top-level science questions: (1) What drives the solar wind and where does the coronal magnetic field originate?; (2) How do solar transients drive heliospheric variability?; (3) How do solar eruptions produce energetic particle radiation that fills the heliosphere?; (4) How does the solar dynamo work and drive connections between the Sun and the heliosphere? Maximising the mission's science return requires considering the characteristics of each orbit, including the relative position of the spacecraft to Earth (affecting downlink rates), trajectory events (such as gravitational assist manoeuvres), and the phase of the solar activity cycle. Furthermore, since each orbit's science telemetry will be downloaded over the course of the following orbit, science operations must be planned at mission level, rather than at the level of individual orbits. It is important to explore the way in which those science questions are translated into an actual plan of observations that fits into the mission, thus ensuring that no opportunities are missed. First, the overarching goals are broken down into specific, answerable questions along with the required observations and the so-called Science Activity Plan (SAP) is developed to achieve this. The SAP groups objectives that require similar observations into Solar Orbiter Observing Plans, resulting in a strategic, top-level view of the optimal opportunities for science observations during the mission lifetime. This allows for all four mission goals to be addressed. In this paper, we introduce Solar Orbiter's SAP through a series of examples and the strategy being followed. Title: Models and data analysis tools for the Solar Orbiter mission Authors: Rouillard, A. P.; Pinto, R. F.; Vourlidas, A.; De Groof, A.; Thompson, W. T.; Bemporad, A.; Dolei, S.; Indurain, M.; Buchlin, E.; Sasso, C.; Spadaro, D.; Dalmasse, K.; Hirzberger, J.; Zouganelis, I.; Strugarek, A.; Brun, A. S.; Alexandre, M.; Berghmans, D.; Raouafi, N. E.; Wiegelmann, T.; Pagano, P.; Arge, C. N.; Nieves-Chinchilla, T.; Lavarra, M.; Poirier, N.; Amari, T.; Aran, A.; Andretta, V.; Antonucci, E.; Anastasiadis, A.; Auchère, F.; Bellot Rubio, L.; Nicula, B.; Bonnin, X.; Bouchemit, M.; Budnik, E.; Caminade, S.; Cecconi, B.; Carlyle, J.; Cernuda, I.; Davila, J. M.; Etesi, L.; Espinosa Lara, F.; Fedorov, A.; Fineschi, S.; Fludra, A.; Génot, V.; Georgoulis, M. K.; Gilbert, H. R.; Giunta, A.; Gomez-Herrero, R.; Guest, S.; Haberreiter, M.; Hassler, D.; Henney, C. J.; Howard, R. A.; Horbury, T. S.; Janvier, M.; Jones, S. I.; Kozarev, K.; Kraaikamp, E.; Kouloumvakos, A.; Krucker, S.; Lagg, A.; Linker, J.; Lavraud, B.; Louarn, P.; Maksimovic, M.; Maloney, S.; Mann, G.; Masson, A.; Müller, D.; Önel, H.; Osuna, P.; Orozco Suarez, D.; Owen, C. J.; Papaioannou, A.; Pérez-Suárez, D.; Rodriguez-Pacheco, J.; Parenti, S.; Pariat, E.; Peter, H.; Plunkett, S.; Pomoell, J.; Raines, J. M.; Riethmüller, T. L.; Rich, N.; Rodriguez, L.; Romoli, M.; Sanchez, L.; Solanki, S. K.; St Cyr, O. C.; Straus, T.; Susino, R.; Teriaca, L.; del Toro Iniesta, J. C.; Ventura, R.; Verbeeck, C.; Vilmer, N.; Warmuth, A.; Walsh, A. P.; Watson, C.; Williams, D.; Wu, Y.; Zhukov, A. N. Bibcode: 2020A&A...642A...2R Altcode: Context. The Solar Orbiter spacecraft will be equipped with a wide range of remote-sensing (RS) and in situ (IS) instruments to record novel and unprecedented measurements of the solar atmosphere and the inner heliosphere. To take full advantage of these new datasets, tools and techniques must be developed to ease multi-instrument and multi-spacecraft studies. In particular the currently inaccessible low solar corona below two solar radii can only be observed remotely. Furthermore techniques must be used to retrieve coronal plasma properties in time and in three dimensional (3D) space. Solar Orbiter will run complex observation campaigns that provide interesting opportunities to maximise the likelihood of linking IS data to their source region near the Sun. Several RS instruments can be directed to specific targets situated on the solar disk just days before data acquisition. To compare IS and RS, data we must improve our understanding of how heliospheric probes magnetically connect to the solar disk.
Aims: The aim of the present paper is to briefly review how the current modelling of the Sun and its atmosphere can support Solar Orbiter science. We describe the results of a community-led effort by European Space Agency's Modelling and Data Analysis Working Group (MADAWG) to develop different models, tools, and techniques deemed necessary to test different theories for the physical processes that may occur in the solar plasma. The focus here is on the large scales and little is described with regards to kinetic processes. To exploit future IS and RS data fully, many techniques have been adapted to model the evolving 3D solar magneto-plasma from the solar interior to the solar wind. A particular focus in the paper is placed on techniques that can estimate how Solar Orbiter will connect magnetically through the complex coronal magnetic fields to various photospheric and coronal features in support of spacecraft operations and future scientific studies.
Methods: Recent missions such as STEREO, provided great opportunities for RS, IS, and multi-spacecraft studies. We summarise the achievements and highlight the challenges faced during these investigations, many of which motivated the Solar Orbiter mission. We present the new tools and techniques developed by the MADAWG to support the science operations and the analysis of the data from the many instruments on Solar Orbiter.
Results: This article reviews current modelling and tool developments that ease the comparison of model results with RS and IS data made available by current and upcoming missions. It also describes the modelling strategy to support the science operations and subsequent exploitation of Solar Orbiter data in order to maximise the scientific output of the mission.
Conclusions: The on-going community effort presented in this paper has provided new models and tools necessary to support mission operations as well as the science exploitation of the Solar Orbiter data. The tools and techniques will no doubt evolve significantly as we refine our procedure and methodology during the first year of operations of this highly promising mission. Title: Understanding the origins of the heliosphere: integrating observations and measurements from Parker Solar Probe, Solar Orbiter, and other space- and ground-based observatories Authors: Velli, M.; Harra, L. K.; Vourlidas, A.; Schwadron, N.; Panasenco, O.; Liewer, P. C.; Müller, D.; Zouganelis, I.; St Cyr, O. C.; Gilbert, H.; Nieves-Chinchilla, T.; Auchère, F.; Berghmans, D.; Fludra, A.; Horbury, T. S.; Howard, R. A.; Krucker, S.; Maksimovic, M.; Owen, C. J.; Rodríguez-Pacheco, J.; Romoli, M.; Solanki, S. K.; Wimmer-Schweingruber, R. F.; Bale, S.; Kasper, J.; McComas, D. J.; Raouafi, N.; Martinez-Pillet, V.; Walsh, A. P.; De Groof, A.; Williams, D. Bibcode: 2020A&A...642A...4V Altcode: Context. The launch of Parker Solar Probe (PSP) in 2018, followed by Solar Orbiter (SO) in February 2020, has opened a new window in the exploration of solar magnetic activity and the origin of the heliosphere. These missions, together with other space observatories dedicated to solar observations, such as the Solar Dynamics Observatory, Hinode, IRIS, STEREO, and SOHO, with complementary in situ observations from WIND and ACE, and ground based multi-wavelength observations including the DKIST observatory that has just seen first light, promise to revolutionize our understanding of the solar atmosphere and of solar activity, from the generation and emergence of the Sun's magnetic field to the creation of the solar wind and the acceleration of solar energetic particles.
Aims: Here we describe the scientific objectives of the PSP and SO missions, and highlight the potential for discovery arising from synergistic observations. Here we put particular emphasis on how the combined remote sensing and in situ observations of SO, that bracket the outer coronal and inner heliospheric observations by PSP, may provide a reconstruction of the solar wind and magnetic field expansion from the Sun out to beyond the orbit of Mercury in the first phases of the mission. In the later, out-of-ecliptic portions of the SO mission, the solar surface magnetic field measurements from SO and the multi-point white-light observations from both PSP and SO will shed light on the dynamic, intermittent solar wind escaping from helmet streamers, pseudo-streamers, and the confined coronal plasma, and on solar energetic particle transport.
Methods: Joint measurements during PSP-SO alignments, and magnetic connections along the same flux tube complemented by alignments with Earth, dual PSP-Earth, and SO-Earth, as well as with STEREO-A, SOHO, and BepiColumbo will allow a better understanding of the in situ evolution of solar-wind plasma flows and the full three-dimensional distribution of the solar wind from a purely observational point of view. Spectroscopic observations of the corona, and optical and radio observations, combined with direct in situ observations of the accelerating solar wind will provide a new foundation for understanding the fundamental physical processes leading to the energy transformations from solar photospheric flows and magnetic fields into the hot coronal plasma and magnetic fields and finally into the bulk kinetic energy of the solar wind and solar energetic particles.
Results: We discuss the initial PSP observations, which already provide a compelling rationale for new measurement campaigns by SO, along with ground- and space-based assets within the synergistic context described above. Title: The Solar Orbiter SPICE instrument. An extreme UV imaging spectrometer Authors: SPICE Consortium; Anderson, M.; Appourchaux, T.; Auchère, F.; Aznar Cuadrado, R.; Barbay, J.; Baudin, F.; Beardsley, S.; Bocchialini, K.; Borgo, B.; Bruzzi, D.; Buchlin, E.; Burton, G.; Büchel, V.; Caldwell, M.; Caminade, S.; Carlsson, M.; Curdt, W.; Davenne, J.; Davila, J.; Deforest, C. E.; Del Zanna, G.; Drummond, D.; Dubau, J.; Dumesnil, C.; Dunn, G.; Eccleston, P.; Fludra, A.; Fredvik, T.; Gabriel, A.; Giunta, A.; Gottwald, A.; Griffin, D.; Grundy, T.; Guest, S.; Gyo, M.; Haberreiter, M.; Hansteen, V.; Harrison, R.; Hassler, D. M.; Haugan, S. V. H.; Howe, C.; Janvier, M.; Klein, R.; Koller, S.; Kucera, T. A.; Kouliche, D.; Marsch, E.; Marshall, A.; Marshall, G.; Matthews, S. A.; McQuirk, C.; Meining, S.; Mercier, C.; Morris, N.; Morse, T.; Munro, G.; Parenti, S.; Pastor-Santos, C.; Peter, H.; Pfiffner, D.; Phelan, P.; Philippon, A.; Richards, A.; Rogers, K.; Sawyer, C.; Schlatter, P.; Schmutz, W.; Schühle, U.; Shaughnessy, B.; Sidher, S.; Solanki, S. K.; Speight, R.; Spescha, M.; Szwec, N.; Tamiatto, C.; Teriaca, L.; Thompson, W.; Tosh, I.; Tustain, S.; Vial, J. -C.; Walls, B.; Waltham, N.; Wimmer-Schweingruber, R.; Woodward, S.; Young, P.; de Groof, A.; Pacros, A.; Williams, D.; Müller, D. Bibcode: 2020A&A...642A..14S Altcode: 2019arXiv190901183A; 2019arXiv190901183S
Aims: The Spectral Imaging of the Coronal Environment (SPICE) instrument is a high-resolution imaging spectrometer operating at extreme ultraviolet wavelengths. In this paper, we present the concept, design, and pre-launch performance of this facility instrument on the ESA/NASA Solar Orbiter mission.
Methods: The goal of this paper is to give prospective users a better understanding of the possible types of observations, the data acquisition, and the sources that contribute to the instrument's signal.
Results: The paper discusses the science objectives, with a focus on the SPICE-specific aspects, before presenting the instrument's design, including optical, mechanical, thermal, and electronics aspects. This is followed by a characterisation and calibration of the instrument's performance. The paper concludes with descriptions of the operations concept and data processing.
Conclusions: The performance measurements of the various instrument parameters meet the requirements derived from the mission's science objectives. The SPICE instrument is ready to perform measurements that will provide vital contributions to the scientific success of the Solar Orbiter mission. Title: The Solar Orbiter Heliospheric Imager (SoloHI) Authors: Howard, R. A.; Vourlidas, A.; Colaninno, R. C.; Korendyke, C. M.; Plunkett, S. P.; Carter, M. T.; Wang, D.; Rich, N.; Lynch, S.; Thurn, A.; Socker, D. G.; Thernisien, A. F.; Chua, D.; Linton, M. G.; Koss, S.; Tun-Beltran, S.; Dennison, H.; Stenborg, G.; McMullin, D. R.; Hunt, T.; Baugh, R.; Clifford, G.; Keller, D.; Janesick, J. R.; Tower, J.; Grygon, M.; Farkas, R.; Hagood, R.; Eisenhauer, K.; Uhl, A.; Yerushalmi, S.; Smith, L.; Liewer, P. C.; Velli, M. C.; Linker, J.; Bothmer, V.; Rochus, P.; Halain, J. -P.; Lamy, P. L.; Auchère, F.; Harrison, R. A.; Rouillard, A.; Patsourakos, S.; St. Cyr, O. C.; Gilbert, H.; Maldonado, H.; Mariano, C.; Cerullo, J. Bibcode: 2020A&A...642A..13H Altcode:
Aims: We present the design and pre-launch performance of the Solar Orbiter Heliospheric Imager (SoloHI) which is an instrument prepared for inclusion in the ESA/NASA Solar Orbiter mission, currently scheduled for launch in 2020.
Methods: The goal of this paper is to provide details of the SoloHI instrument concept, design, and pre-flight performance to give the potential user of the data a better understanding of how the observations are collected and the sources that contribute to the signal.
Results: The paper discusses the science objectives, including the SoloHI-specific aspects, before presenting the design concepts, which include the optics, mechanical, thermal, electrical, and ground processing. Finally, a list of planned data products is also presented.
Conclusions: The performance measurements of the various instrument parameters meet or exceed the requirements derived from the mission science objectives. SoloHI is poised to take its place as a vital contributor to the science success of the Solar Orbiter mission. Title: The Solar Orbiter mission. Science overview Authors: Müller, D.; St. Cyr, O. C.; Zouganelis, I.; Gilbert, H. R.; Marsden, R.; Nieves-Chinchilla, T.; Antonucci, E.; Auchère, F.; Berghmans, D.; Horbury, T. S.; Howard, R. A.; Krucker, S.; Maksimovic, M.; Owen, C. J.; Rochus, P.; Rodriguez-Pacheco, J.; Romoli, M.; Solanki, S. K.; Bruno, R.; Carlsson, M.; Fludra, A.; Harra, L.; Hassler, D. M.; Livi, S.; Louarn, P.; Peter, H.; Schühle, U.; Teriaca, L.; del Toro Iniesta, J. C.; Wimmer-Schweingruber, R. F.; Marsch, E.; Velli, M.; De Groof, A.; Walsh, A.; Williams, D. Bibcode: 2020A&A...642A...1M Altcode: 2020arXiv200900861M
Aims: Solar Orbiter, the first mission of ESA's Cosmic Vision 2015-2025 programme and a mission of international collaboration between ESA and NASA, will explore the Sun and heliosphere from close up and out of the ecliptic plane. It was launched on 10 February 2020 04:03 UTC from Cape Canaveral and aims to address key questions of solar and heliospheric physics pertaining to how the Sun creates and controls the Heliosphere, and why solar activity changes with time. To answer these, the mission carries six remote-sensing instruments to observe the Sun and the solar corona, and four in-situ instruments to measure the solar wind, energetic particles, and electromagnetic fields. In this paper, we describe the science objectives of the mission, and how these will be addressed by the joint observations of the instruments onboard.
Methods: The paper first summarises the mission-level science objectives, followed by an overview of the spacecraft and payload. We report the observables and performance figures of each instrument, as well as the trajectory design. This is followed by a summary of the science operations concept. The paper concludes with a more detailed description of the science objectives.
Results: Solar Orbiter will combine in-situ measurements in the heliosphere with high-resolution remote-sensing observations of the Sun to address fundamental questions of solar and heliospheric physics. The performance of the Solar Orbiter payload meets the requirements derived from the mission's science objectives. Its science return will be augmented further by coordinated observations with other space missions and ground-based observatories.

ARRAY(0x207ce98) Title: The Solar Orbiter EUI instrument: The Extreme Ultraviolet Imager Authors: Rochus, P.; Auchère, F.; Berghmans, D.; Harra, L.; Schmutz, W.; Schühle, U.; Addison, P.; Appourchaux, T.; Aznar Cuadrado, R.; Baker, D.; Barbay, J.; Bates, D.; BenMoussa, A.; Bergmann, M.; Beurthe, C.; Borgo, B.; Bonte, K.; Bouzit, M.; Bradley, L.; Büchel, V.; Buchlin, E.; Büchner, J.; Cabé, F.; Cadiergues, L.; Chaigneau, M.; Chares, B.; Choque Cortez, C.; Coker, P.; Condamin, M.; Coumar, S.; Curdt, W.; Cutler, J.; Davies, D.; Davison, G.; Defise, J. -M.; Del Zanna, G.; Delmotte, F.; Delouille, V.; Dolla, L.; Dumesnil, C.; Dürig, F.; Enge, R.; François, S.; Fourmond, J. -J.; Gillis, J. -M.; Giordanengo, B.; Gissot, S.; Green, L. M.; Guerreiro, N.; Guilbaud, A.; Gyo, M.; Haberreiter, M.; Hafiz, A.; Hailey, M.; Halain, J. -P.; Hansotte, J.; Hecquet, C.; Heerlein, K.; Hellin, M. -L.; Hemsley, S.; Hermans, A.; Hervier, V.; Hochedez, J. -F.; Houbrechts, Y.; Ihsan, K.; Jacques, L.; Jérôme, A.; Jones, J.; Kahle, M.; Kennedy, T.; Klaproth, M.; Kolleck, M.; Koller, S.; Kotsialos, E.; Kraaikamp, E.; Langer, P.; Lawrenson, A.; Le Clech', J. -C.; Lenaerts, C.; Liebecq, S.; Linder, D.; Long, D. M.; Mampaey, B.; Markiewicz-Innes, D.; Marquet, B.; Marsch, E.; Matthews, S.; Mazy, E.; Mazzoli, A.; Meining, S.; Meltchakov, E.; Mercier, R.; Meyer, S.; Monecke, M.; Monfort, F.; Morinaud, G.; Moron, F.; Mountney, L.; Müller, R.; Nicula, B.; Parenti, S.; Peter, H.; Pfiffner, D.; Philippon, A.; Phillips, I.; Plesseria, J. -Y.; Pylyser, E.; Rabecki, F.; Ravet-Krill, M. -F.; Rebellato, J.; Renotte, E.; Rodriguez, L.; Roose, S.; Rosin, J.; Rossi, L.; Roth, P.; Rouesnel, F.; Roulliay, M.; Rousseau, A.; Ruane, K.; Scanlan, J.; Schlatter, P.; Seaton, D. B.; Silliman, K.; Smit, S.; Smith, P. J.; Solanki, S. K.; Spescha, M.; Spencer, A.; Stegen, K.; Stockman, Y.; Szwec, N.; Tamiatto, C.; Tandy, J.; Teriaca, L.; Theobald, C.; Tychon, I.; van Driel-Gesztelyi, L.; Verbeeck, C.; Vial, J. -C.; Werner, S.; West, M. J.; Westwood, D.; Wiegelmann, T.; Willis, G.; Winter, B.; Zerr, A.; Zhang, X.; Zhukov, A. N. Bibcode: 2020A&A...642A...8R Altcode: Context. The Extreme Ultraviolet Imager (EUI) is part of the remote sensing instrument package of the ESA/NASA Solar Orbiter mission that will explore the inner heliosphere and observe the Sun from vantage points close to the Sun and out of the ecliptic. Solar Orbiter will advance the "connection science" between solar activity and the heliosphere.
Aims: With EUI we aim to improve our understanding of the structure and dynamics of the solar atmosphere, globally as well as at high resolution, and from high solar latitude perspectives.
Methods: The EUI consists of three telescopes, the Full Sun Imager and two High Resolution Imagers, which are optimised to image in Lyman-α and EUV (17.4 nm, 30.4 nm) to provide a coverage from chromosphere up to corona. The EUI is designed to cope with the strong constraints imposed by the Solar Orbiter mission characteristics. Limited telemetry availability is compensated by state-of-the-art image compression, onboard image processing, and event selection. The imposed power limitations and potentially harsh radiation environment necessitate the use of novel CMOS sensors. As the unobstructed field of view of the telescopes needs to protrude through the spacecraft's heat shield, the apertures have been kept as small as possible, without compromising optical performance. This led to a systematic effort to optimise the throughput of every optical element and the reduction of noise levels in the sensor.
Results: In this paper we review the design of the two elements of the EUI instrument: the Optical Bench System and the Common Electronic Box. Particular attention is also given to the onboard software, the intended operations, the ground software, and the foreseen data products.
Conclusions: The EUI will bring unique science opportunities thanks to its specific design, its viewpoint, and to the planned synergies with the other Solar Orbiter instruments. In particular, we highlight science opportunities brought by the out-of-ecliptic vantage point of the solar poles, the high-resolution imaging of the high chromosphere and corona, and the connection to the outer corona as observed by coronagraphs. Title: Metis: the Solar Orbiter visible light and ultraviolet coronal imager Authors: Antonucci, Ester; Romoli, Marco; Andretta, Vincenzo; Fineschi, Silvano; Heinzel, Petr; Moses, J. Daniel; Naletto, Giampiero; Nicolini, Gianalfredo; Spadaro, Daniele; Teriaca, Luca; Berlicki, Arkadiusz; Capobianco, Gerardo; Crescenzio, Giuseppe; Da Deppo, Vania; Focardi, Mauro; Frassetto, Fabio; Heerlein, Klaus; Landini, Federico; Magli, Enrico; Marco Malvezzi, Andrea; Massone, Giuseppe; Melich, Radek; Nicolosi, Piergiorgio; Noci, Giancarlo; Pancrazzi, Maurizio; Pelizzo, Maria G.; Poletto, Luca; Sasso, Clementina; Schühle, Udo; Solanki, Sami K.; Strachan, Leonard; Susino, Roberto; Tondello, Giuseppe; Uslenghi, Michela; Woch, Joachim; Abbo, Lucia; Bemporad, Alessandro; Casti, Marta; Dolei, Sergio; Grimani, Catia; Messerotti, Mauro; Ricci, Marco; Straus, Thomas; Telloni, Daniele; Zuppella, Paola; Auchère, Frederic; Bruno, Roberto; Ciaravella, Angela; Corso, Alain J.; Alvarez Copano, Miguel; Aznar Cuadrado, Regina; D'Amicis, Raffaella; Enge, Reiner; Gravina, Alessio; Jejčič, Sonja; Lamy, Philippe; Lanzafame, Alessandro; Meierdierks, Thimo; Papagiannaki, Ioanna; Peter, Hardi; Fernandez Rico, German; Giday Sertsu, Mewael; Staub, Jan; Tsinganos, Kanaris; Velli, Marco; Ventura, Rita; Verroi, Enrico; Vial, Jean-Claude; Vives, Sebastien; Volpicelli, Antonio; Werner, Stephan; Zerr, Andreas; Negri, Barbara; Castronuovo, Marco; Gabrielli, Alessandro; Bertacin, Roberto; Carpentiero, Rita; Natalucci, Silvia; Marliani, Filippo; Cesa, Marco; Laget, Philippe; Morea, Danilo; Pieraccini, Stefano; Radaelli, Paolo; Sandri, Paolo; Sarra, Paolo; Cesare, Stefano; Del Forno, Felice; Massa, Ernesto; Montabone, Mauro; Mottini, Sergio; Quattropani, Daniele; Schillaci, Tiziano; Boccardo, Roberto; Brando, Rosario; Pandi, Arianna; Baietto, Cristian; Bertone, Riccardo; Alvarez-Herrero, Alberto; García Parejo, Pilar; Cebollero, María; Amoruso, Mauro; Centonze, Vito Bibcode: 2020A&A...642A..10A Altcode: 2019arXiv191108462A
Aims: Metis is the first solar coronagraph designed for a space mission and is capable of performing simultaneous imaging of the off-limb solar corona in both visible and UV light. The observations obtained with Metis aboard the Solar Orbiter ESA-NASA observatory will enable us to diagnose, with unprecedented temporal coverage and spatial resolution, the structures and dynamics of the full corona in a square field of view (FoV) of ±2.9° in width, with an inner circular FoV at 1.6°, thus spanning the solar atmosphere from 1.7 R to about 9 R, owing to the eccentricity of the spacecraft orbit. Due to the uniqueness of the Solar Orbiter mission profile, Metis will be able to observe the solar corona from a close (0.28 AU, at the closest perihelion) vantage point, achieving increasing out-of-ecliptic views with the increase of the orbit inclination over time. Moreover, observations near perihelion, during the phase of lower rotational velocity of the solar surface relative to the spacecraft, allow longer-term studies of the off-limb coronal features, thus finally disentangling their intrinsic evolution from effects due to solar rotation.
Methods: Thanks to a novel occultation design and a combination of a UV interference coating of the mirrors and a spectral bandpass filter, Metis images the solar corona simultaneously in the visible light band, between 580 and 640 nm, and in the UV H I Lyman-α line at 121.6 nm. The visible light channel also includes a broadband polarimeter able to observe the linearly polarised component of the K corona. The coronal images in both the UV H I Lyman-α and polarised visible light are obtained at high spatial resolution with a spatial scale down to about 2000 km and 15 000 km at perihelion, in the cases of the visible and UV light, respectively. A temporal resolution down to 1 s can be achieved when observing coronal fluctuations in visible light.
Results: The Metis measurements, obtained from different latitudes, will allow for complete characterisation of the main physical parameters and dynamics of the electron and neutral hydrogen/proton plasma components of the corona in the region where the solar wind undergoes the acceleration process and where the onset and initial propagation of coronal mass ejections (CMEs) take place. The near-Sun multi-wavelength coronal imaging performed with Metis, combined with the unique opportunities offered by the Solar Orbiter mission, can effectively address crucial issues of solar physics such as: the origin and heating/acceleration of the fast and slow solar wind streams; the origin, acceleration, and transport of the solar energetic particles; and the transient ejection of coronal mass and its evolution in the inner heliosphere, thus significantly improving our understanding of the region connecting the Sun to the heliosphere and of the processes generating and driving the solar wind and coronal mass ejections.
Conclusions: This paper presents the scientific objectives and requirements, the overall optical design of the Metis instrument, the thermo-mechanical design, and the processing and power unit; reports on the results of the campaigns dedicated to integration, alignment, and tests, and to the characterisation of the instrument performance; describes the operation concept, data handling, and software tools; and, finally, the diagnostic techniques to be applied to the data, as well as a brief description of the expected scientific products. The performance of the instrument measured during calibrations ensures that the scientific objectives of Metis can be pursued with success.

Metis website: http://metis.oato.inaf.it Title: The Solaris Solar Polar Mission Authors: Hassler, Donald M.; Newmark, Jeff; Gibson, Sarah; Harra, Louise; Appourchaux, Thierry; Auchere, Frederic; Berghmans, David; Colaninno, Robin; Fineschi, Silvano; Gizon, Laurent; Gosain, Sanjay; Hoeksema, Todd; Kintziger, Christian; Linker, John; Rochus, Pierre; Schou, Jesper; Viall, Nicholeen; West, Matt; Woods, Tom; Wuelser, Jean-Pierre Bibcode: 2020EGUGA..2217703H Altcode: The solar poles are one of the last unexplored regions of the solar system. Although Ulysses flew over the poles in the 1990s, it did not have remote sensing instruments onboard to probe the Sun's polar magnetic field or surface/sub-surface flows.We will discuss Solaris, a proposed Solar Polar MIDEX mission to revolutionize our understanding of the Sun by addressing fundamental questions that can only be answered from a polar vantage point. Solaris uses a Jupiter gravity assist to escape the ecliptic plane and fly over both poles of the Sun to >75 deg. inclination, obtaining the first high-latitude, multi-month-long, continuous remote-sensing solar observations. Solaris will address key outstanding, breakthrough problems in solar physics and fill holes in our scientific understanding that will not be addressed by current missions.With focused science and a simple, elegant mission design, Solaris will also provide enabling observations for space weather research (e.g. polar view of CMEs), and stimulate future research through new unanticipated discoveries. Title: Spectroscopic detection of coronal plasma flows in loops undergoing thermal non-equilibrium cycles Authors: Pelouze, Gabriel; Auchère, Frédéric; Bocchialini, Karine; Froment, Clara; Parenti, Susanna; Soubrié, Elie Bibcode: 2020A&A...634A..54P Altcode: 2019arXiv191202538P Context. Long-period intensity pulsations were recently detected in the EUV emission of coronal loops and attributed to cycles of plasma evaporation and condensation driven by thermal non-equilibrium (TNE). Numerical simulations that reproduce this phenomenon also predict the formation of periodic flows of plasma at coronal temperatures along some of the pulsating loops.
Aims: We aim to detect these predicted flows of coronal-temperature plasma in pulsating loops.
Methods: We used time series of spatially resolved spectra from the EUV imaging spectrometer (EIS) onboard Hinode and tracked the evolution of the Doppler velocity in loops in which intensity pulsations have previously been detected in images of SDO/AIA.
Results: We measured signatures of flows that are compatible with the simulations but only for a fraction of the observed events. We demonstrate that this low detection rate can be explained by line of sight ambiguities combined with instrumental limitations, such as low signal-to-noise ratio or insufficient cadence.

Movies associated to Figs. 1, 4, 7, 10 are available at https://www.aanda.org Title: Global helium abundance measurements in the solar corona Authors: Moses, John D.; Antonucci, Ester; Newmark, Jeffrey; Auchère, Frédéric; Fineschi, Silvano; Romoli, Marco; Telloni, Daniele; Massone, Giuseppe; Zangrilli, Luca; Focardi, Mauro; Landini, Federico; Pancrazzi, Maurizio; Rossi, Guglielmo; Malvezzi, Andrea M.; Wang, Dennis; Leclec'h, Jean-Christophe; Moalic, Jean-Pierre; Rouesnel, Frédéric; Abbo, Lucia; Canou, Aurélien; Barbey, Nicolas; Guennou, Chloé; Laming, John M.; Lemen, James; Wuelser, Jean-Pierre; Kohl, John L.; Gardner, Lawrence D. Bibcode: 2020NatAs...4.1134M Altcode: 2020NatAs.tmp..152M Solar abundances have been historically assumed to be representative of cosmic abundances. However, our knowledge of the solar abundance of helium, the second most abundant element, relies mainly on models1 and indirect measurements through helioseismic observations2, because actual measurements of helium in the solar atmosphere are very scarce. Helium cannot be directly measured in the photosphere because of its high first ionization potential, and measurements of its abundance in the inner corona have been sporadic3,4. In this Letter, we present simultaneous global images of the helium (out to a heliocentric distance of 3R (solar radii)) and hydrogen emission in the solar corona during the minimum of solar activity of cycle 23 and directly derive the helium abundance in the streamer region and surrounding corona (out to 2.2R). The morphology of the He+ corona is markedly different from that of the H corona, owing to significant spatial variations in helium abundance. The observations show that the helium abundance is shaped according to and modulated by the structure of the large-scale coronal magnetic field and that helium is almost completely depleted in the equatorial regions during the quiet Sun. This measurement provides a trace back to the coronal source of the anomalously slow solar wind observed in the heliosphere at the Sun-Earth Lagrangian point L1 in 2009, during the exceptionally long-lasting minimum of solar activity cycle 23. Title: The SPICE (Spectral Imaging of the Coronal Environment) Ultraviolet Imaging Spectrograph Investigation Authors: Hassler, D.; Auchere, F.; Carlsson, M.; Fludra, A.; Giunta, A. S.; Mueller, D.; Peter, H.; Parenti, S.; Teriaca, L.; Fredvik, T. Bibcode: 2019AGUFMSH24A..02H Altcode: One of the primary objectives of the Solar Orbiter mission is to link remote sensing observations of the solar surface structures with in-situ observations of solar wind streams. The SPICE (Spectral Imaging of the Coronal Environment) instrument will characterize the plasma properties of regions near the Sun to directly compare with in-situ measurements from both Solar Orbiter & Parker Solar Probe. Specifically, SPICE will map outflow velocities of surface features to solar wind structures with similar composition (FIP, M/q) measured in-situ by the SWA/HIS instrument on Solar Orbiter. These observations will help discriminate models of solar wind origin by matching composition signatures in solar wind streams to surface feature composition, and discriminate physical processes that inject material from closed structures into solar wind streams.

This presentation will provide an overview of the SPICE investigation, including science & measurement objective, instrument design, capabilities and performance as measured during calibration prior to delivery to the Solar Orbiter spacecraft. The presentation will also provide a description of the operations concept and data processing during the mission. Title: The Solar Orbiter EUI instrument: The Extreme Ultraviolet Imager Authors: Rochus, P. L.; Auchere, F.; Berghmans, D.; Harra, L.; Schmutz, W. K.; Schühle, U. Bibcode: 2019AGUFMSH21D3291R Altcode: The Extreme Ultraviolet Imager (EUI) is part of the remote sensing instrument package of the ESA/NASA Solar Orbiter mission that will explore the inner heliosphere and observe the Sun from vantage points close to the Sun and out-of-the-ecliptic.

EUI aims at improving our understanding of the structure and dynamics of the solar atmosphere. EUI will take images of the solar atmosphere, globally as well as at high resolution, and from high solar latitude perspectives.

EUI consists of 3 telescopes that are optimized to image in Lyman-a and EUV 17.4nm and 30.4 nm to provide a coverage from chromosphere up to corona. EUI is designed to cope with the strong constraints that Solar Orbiter has as a deep space mission. Limited telemetry availability is compensated by state-of-the-art image compression, on board image processing and event selection. The imposed power limitations and potentially harsh radiation environment lead to the usage of novel CMOS sensors. As the unobstructed field of view of the telescopes needs to protrude through the spacecraft heat shield, the apertures were kept as small as possible. This lead to a systematic effort to optimize the throughput of every optical element and the reduction of noise levels in the sensor.

In this paper we review the design of the two elements of the EUI instrument: the Optical Bench System and the Common Electronic Box. Particular attention is also given to the on board software, the intended operations, the ground software and the foreseen data products.

EUI will bring unique science opportunities thanks to its specific design, its viewpoint and thanks to the planned synergies with the other Solar Orbiter instruments. We highlight in particular science opportunities brought by the out-of-ecliptic vantage point of the solar poles, the high resolution imaging of the high chromosphere and corona, and the connection to the outer corona as observed by coronagraphs. Title: The Chromospheric Layer Spectro-Polarimeter (CLASP2) Sounding Rocket Mission: First Results Authors: McKenzie, D. E.; Ishikawa, R.; Trujillo Bueno, J.; Auchere, F.; Rachmeler, L.; Kano, R.; Song, D.; Okamoto, J.; Kobayashi, K.; Yoshida, M. Bibcode: 2019AGUFMSH44A..06M Altcode: A major challenge for heliophysics is to decipher the magnetic structure of the chromosphere, because of its vital role in the transport of energy into the corona and solar wind. Routine satellite measurements of the chromospheric magnetic field will dramatically improve our understanding of the chromosphere and its connection to the rest of the solar atmosphere. Before such a satellite can be considered for flight, we must refine the measurement techniques by exploring emission lines with a range of magnetic sensitivities. In 2015, CLASP achieved the first measurement of linear polarization produced by scattering processes in a far UV resonance line (hydrogen Lyman­-α), and the first exploration of the magnetic field (via the Hanle effect) and geometrical complexity in quiet regions of the chromosphere/­corona transition region. These measurements are a first step towards routine quantitative characterization of the local thermal and magnetic conditions in this key layer of the solar atmosphere.

Nonetheless, Lyman­-α is only one of the magnetically sensitive spectral lines in the UV spectrum. CLASP2 extends the capability of UV spectropolarimetry by acquiring ground­breaking measurements in the Mg II h and k spectral lines near 280 nm, whose cores form about 100 km below the Lyman-­α core. These lines are sensitive to a larger range of field strengths than Lyman­-α, through both the Hanle and Zeeman effects. CLASP2 captures measurements of linear and circular polarization to enable the first determination of all 4 Stokes parameters in chromospheric UV radiation. Coupled with numerical modeling of the observed spectral line polarization (anisotropic radiation pumping with Hanle, Zeeman and magneto-­optical effects), CLASP2 is a pathfinder for determination of the magnetic field's strength and direction, as well as of the geometry of the plasma in the upper solar chromosphere.

CLASP2 was launched from White Sands Missile Range in April 2019. In this presentation, we will summarize the characteristics of the CLASP2 flight, the performance of the UV telescope and spectropolarimeter, and our preliminary findings. Title: From PROBA2/SWAP to Solar Orbiter/EUI: exploring the outer edge of the EUV corona. Authors: Berghmans, D.; D'Huys, E.; Zhukov, A.; Auchere, F. Bibcode: 2019AGUFMSH13A..01B Altcode: SWAP is a small coronal EUV imager onboard the ESA microsatellite PROBA2. Thanks to its large field of view (54 arcmin), spacecraft offpoints and applied image processing, SWAP has been able to show the structures of the EUV corona more than 1 Rsun above the limb. This "middle corona" is in between the classical off limb EUV corona as seen by e.g. SDO/AIA and the much further white light corona as seen by e.g. the LASCO coronagraphs and is thus a poorly observed region. The Middle Corona harbours interesting physics, as it is here where the solar wind accelerates and the topology of streamers and pseudo-streamers fade in the solar wind. SWAP imagery has shown how 'coronal fan' structures in the middle corona survive many solar rotations and how the extended corona above the solar poles reverses polarity. The Full Sun Imager (FSI, part of Extreme Ultraviolet Imager EUI onboard Solar Orbiter) will take this further with a field of view of 228 arcmin. Furthermore, as embarked on the Solar Orbiter mission (launch 2020) FSI will be the first to image all this from out of the ecliptic. In this paper we will review the Middle Corona results of SWAP and provide an outlook on what to expect from EUI/FSI. Title: Center-to-Limb Variation of the polarization of Mg II h & k lines as measured by CLASP2 Authors: Rachmeler, L.; McKenzie, D. E.; Ishikawa, R.; Kano, R.; Trujillo Bueno, J.; Kobayashi, K.; Song, D.; Yoshida, M.; Auchere, F.; Okamoto, J. Bibcode: 2019AGUFMSH11D3380R Altcode: The Chromospheric LAyer SpectroPolarimeter 2 (CLASP2) is a sounding rocket that was launched from White Sands Missile Range in April 2019. CLASP2 is a reflight of the CLASP instrument, and has been modified to observe the polarization of the Magnesium II h & k lines in the solar chromosphere. The instrument contains a slit-jaw context imager at Lyman Alpha (~121.6nm) and two spectropolarimetric cameras that capture Mg II h & k near 280nm. A rotating polarization modulation unit allows us to capture the full polarization state of Mg II h & k; the measured polarization signals are sensitive to the Hanle and the Zeeman magnetic effects, and magneto-optical effects. The center-to-limb variations (CLV) of the intensity of these lines has been measured, but the CLV of the polarization signals has only been investigated theoretically. The first flight of CLASP, which measured the linear polarization of the Lyman alpha line, found a surprising lack of CLV in the line core (Kano et al. 2017), which has important implications for the magnetic strength and geometrical complexity of the chromosphere-corona transition region (Trujillo Bueno et al. 2018). We present here initial results on the CLV of the Mg II polarization signals. Title: High-frequency Wave Propagation Along a Spicule Observed by CLASP Authors: Yoshida, Masaki; Suematsu, Yoshinori; Ishikawa, Ryohko; Okamoto, Takenori J.; Kubo, Masahito; Kano, Ryouhei; Narukage, Noriyuki; Bando, Takamasa; Winebarger, Amy R.; Kobayashi, Ken; Trujillo Bueno, Javier; Auchère, Frédéric Bibcode: 2019ApJ...887....2Y Altcode: The Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP) sounding rocket experiment, launched in 2015 September, observed the hydrogen Lyα line (121.6 nm) in an unprecedented high temporal cadence of 0.3 s. CLASP performed sit-and-stare observations of the quiet Sun near the limb for 5 minutes with a slit perpendicular to the limb and successfully captured an off-limb spicule evolving along the slit. The Lyα line is well suited for investigating how spicules affect the corona because it is sensitive to higher temperatures than other chromospheric lines, owing to its large optical thickness. We found high-frequency oscillations of the Doppler velocity with periods of 20-50 s and low-frequency oscillation of periods of ∼240 s on the spicule. From a wavelet analysis of the time sequence data of the Doppler velocity, in the early phase of the spicule evolution, we found that waves with a period of ∼30 s and a velocity amplitude of 2-3 km s-1 propagated upward along the spicule with a phase velocity of ∼470 km s-1. In contrast, in the later phase, possible downward and standing waves with smaller velocity amplitudes were also observed. The high-frequency waves observed in the early phase of the spicule evolution would be related with the dynamics and the formation of the spicules. Our analysis enabled us to identify the upward, downward, and standing waves along the spicule and to obtain the velocity amplitude of each wave directly from the Doppler velocity for the first time. We evaluated the energy flux by the upward-propagating waves along the spicule, and discussed the impact to the coronal heating. Title: Pointing the NTT at the Sun: Studying the Solar Corona During the Total Eclipse Authors: Dennefeld, M.; Koutchmy, S.; Sèvre, F.; Fathivavsari, H.; Auchère, F.; Baudin, F.; Abdi, S.; Sinclaire, P.; Saviane, I.; Labraña, F.; Schmidtobreick, L. Bibcode: 2019Msngr.177...54D Altcode: No abstract at ADS Title: The Solar-C_EUVST mission Authors: Shimizu, Toshifumi; Imada, Shinsuke; Kawate, Tomoko; Ichimoto, Kiyoshi; Suematsu, Yoshinori; Hara, Hirohisa; Katsukawa, Yukio; Kubo, Masahito; Toriumi, Shin; Watanabe, Tetsuya; Yokoyama, Takaaki; Korendyke, Clarence M.; Warren, Harry P.; Tarbell, Ted; De Pontieu, Bart; Teriaca, Luca; Schühle, Udo H.; Solanki, Sami; Harra, Louise K.; Matthews, Sarah; Fludra, A.; Auchère, F.; Andretta, V.; Naletto, G.; Zhukov, A. Bibcode: 2019SPIE11118E..07S Altcode: Solar-C EUVST (EUV High-Throughput Spectroscopic Telescope) is a solar physics mission concept that was selected as a candidate for JAXA competitive M-class missions in July 2018. The onboard science instrument, EUVST, is an EUV spectrometer with slit-jaw imaging system that will simultaneously observe the solar atmosphere from the photosphere/chromosphere up to the corona with seamless temperature coverage, high spatial resolution, and high throughput for the first time. The mission is designed to provide a conclusive answer to the most fundamental questions in solar physics: how fundamental processes lead to the formation of the solar atmosphere and the solar wind, and how the solar atmosphere becomes unstable, releasing the energy that drives solar flares and eruptions. The entire instrument structure and the primary mirror assembly with scanning and tip-tilt fine pointing capability for the EUVST are being developed in Japan, with spectrograph and slit-jaw imaging hardware and science contributions from US and European countries. The mission will be launched and installed in a sun-synchronous polar orbit by a JAXA Epsilon vehicle in 2025. ISAS/JAXA coordinates the conceptual study activities during the current mission definition phase in collaboration with NAOJ and other universities. The team is currently working towards the JAXA final down-selection expected at the end of 2019, with strong support from US and European colleagues. The paper provides an overall description of the mission concept, key technologies, and the latest status. Title: Optical alignment of the Solar Orbiter EUI flight instrument Authors: Mazzoli, A.; Halain, J. -P.; Auchère, F.; Barbay, J.; Meining, S.; Philippon, A.; Morinaud, G.; Roose, S.; Hellin, M. -L.; Jacques, L.; Schühle, U.; Dumesnil, C.; Mercier, R.; Renotte, E.; Rochus, P. Bibcode: 2019SPIE11180E..1OM Altcode: The Extreme Ultraviolet Imager (EUI) instrument for the Solar Orbiter mission will image the solar corona in the extreme ultraviolet (17.1 nm and 30.4 nm) and in the vacuum ultraviolet (121.6 nm). It is composed of three channels, each one containing a telescope. Two of these channels are high resolution imagers (HRI) at respectively 17.1 nm (HRI-EUV) and 121.6 nm (HRI-Ly ), each one composed of two off-axis aspherical mirrors. The third channel is a full sun imager (FSI) composed of one single off-axis aspherical mirror and working at 17.1 nm and 30.4 nm alternatively. This paper presents the optical alignment of each telescope. The alignment process involved a set of Optical Ground Support Equipment (OGSE) such as theodolites, laser tracker, visible-light interferometer as well as a 3D Coordinates Measuring Machine (CMM). The mirrors orientation have been measured with respect to reference alignment cubes using theodolites. Their positions with respect to reference pins on the instrument optical bench have been measured using the 3D CMM. The mirrors orientations and positions have been adjusted by shimming of the mirrors mount during the alignment process. After this mechanical alignment, the quality of the wavefront has been checked by interferometric measurements, in an iterative process with the orientation and position adjustment to achieve the required image quality. Title: The Chromospheric Layer Spectro-Polarimeter (CLASP2) Sounding Rocket Mission: First Results Authors: McKenzie, David Eugene; Ishikawa, Ryohko; Kano, Ryouhei; Rachmeler, Laurel; Trujillo Bueno, Javier; Kobayashi, Ken; Song, Donguk; Yoshida, Masaki; Auchere, Frederic; Okamoto, Takenori Bibcode: 2019AAS...23412601M Altcode: A major challenge for heliophysics is to decipher the magnetic structure of the chromosphere, because of its vital role in the transport of energy into the corona and solar wind. Routine satellite measurements of the chromospheric magnetic field will dramatically improve our understanding of the chromosphere and its connection to the rest of the solar atmosphere. Before such a satellite can be considered for flight, we must refine the measurement techniques by exploring emission lines with a range of magnetic sensitivities. In 2015, CLASP achieved the first measurement of linear polarization produced by scattering processes in a far UV resonance line (hydrogen Lyman-α), and the first exploration of the magnetic field (via the Hanle effect) and geometrical complexity in quiet regions of the chromosphere-corona transition region. These measurements are a first step towards routine quantitative characterization of the local thermal and magnetic conditions in this key layer of the solar atmosphere.

Nonetheless, Lyman-α is only one of the magnetically sensitive spectral lines in the UV spectrum. CLASP2 extends the capability of UV spectropolarimetry by acquiring ground-breaking measurements in the Mg II h and k spectral lines near 280 nm, whose cores form about 100 km below the Lyman-α core. These lines are sensitive to a larger range of field strengths than Lyman-α, through both the Hanle and Zeeman effects. CLASP2 will capture measurements of linear and circular polarization to enable the first determination of all 4 Stokes parameters in chromospheric UV radiation. Coupled with numerical modeling of the observed spectral line polarization (anisotropic radiation pumping with Hanle, Zeeman and magneto-optical effects), CLASP2 is a pathfinder for determination of the magnetic field's strength and direction, as well as of the geometry of the plasma in the upper solar chromosphere.

CLASP2 will launch from White Sands Missile Range in April 2019. In this presentation, we will summarize the characteristics of the CLASP2 flight, the performance of the UV telescope and spectropolarimeter, and our preliminary findings. Title: Lyman-α imaging polarimetry with the CLASP2 sounding rocket mission Authors: Kano, Ryouhei; Ishikawa, Ryohko; McKenzie, David Eugene; Trujillo Bueno, Javier; Song, Donguk; Yoshida, Masaki; Okamoto, Takenori; Rachmeler, Laurel; Kobayashi, Ken; Auchere, Frederic Bibcode: 2019AAS...23430216K Altcode: Ultraviolet polarimetry offers a unique opportunity to explore the upper solar chromosphere and the transition region (TR) to the million-degree corona. These outer atmospheric regions play a key role in the transfer of mass and energy from the solar photosphere to the corona. With a sounding rocket experiment called the Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP), in September 2015 we succeeded in obtaining the first measurement of the linear polarization produced by scattering processes in the hydrogen Lyman-α line of the solar disk radiation. The analysis and interpretation of such spectro-polarimetric observation allowed us to obtain information on the geometrical complexity of the corrugated surface that delineates the TR, as well as on the magnetic field strength via the Hanle effect. At the same time, the CLASP slit-jaw (SJ) optics system, which is a Lyman-α filter imager characterized by a FWHM= 7 nm, allowed us to obtain broad-band Stokes-I and Q/I images over a large field of view. The obtained broad-band Q/I images are dominated by the scattering polarization signals of the Lyman-α wings, and not by the much weaker line-center signals where the Hanle effect operates. Recently, Alsina Ballester et al. (2019, ApJ, in press) showed that the scattering polarization signals of the Lyman-α wings are sensitive to chromospheric magnetic fields via the magneto-optical effects. Therefore, Lyman-α imaging polarimetry is of scientific interest also for magnetic-field investigations. On April 11, 2019, we performed another sounding rocket experiment, called the Chromospheric LAyer Spectro-Polarimeter (CLASP2). We used the same instrument after significant modifications in order to obtain spectro-polarimetric observations of a plage and a quiet region in the ionized magnesium lines around 280 nm (i.e., the Mg II h & k lines). At the same time, the CLASP2 SJ optics system allowed us to obtain broad-band Q/I and U/I images at the Lyman-α wavelength, in addition to the well-known SJ intensity images. In this presentation, we provide a first overview of the CLASP2 SJ data. Title: Modeling the Scattering Polarization of the Hydrogen Lyα Line Observed by CLASP in a Filament Channel Authors: Štěpán, J.; Trujillo Bueno, J.; Gunár, S.; Heinzel, P.; del Pino Alemán, T.; Kano, R.; Ishikawa, R.; Narukage, N.; Bando, T.; Winebarger, A.; Kobayashi, K.; Auchère, F. Bibcode: 2019ASPC..526..165S Altcode: The 400 arcsec spectrograph slit of CLASP crossed mainly quiet regions of the solar chromosphere, from the limb towards the solar disk center. Interestingly, in the CLASP slit-jaw images and in the SDO images of the He II line at 304 Å, we can identify a filament channel (FC) extending over more than 60 arcsec crossing the slit of the spectrograph. In order to interpret the peculiar spatial variation of the Q/I and U/I signals observed by CLASP in the hydrogen Lyα line (1216 Å), we perform multi-dimensional radiative transfer modeling in given filament models. In this contribution, we show the first results of the two-dimensional calculations we have carried out, with the aim of determining the filament thermal and magnetic structure by comparing the theoretical and the observed polarization signals. Our results suggest that the temperature gradients in the filament observed by CLASP are significantly larger than previously thought. Title: Comprehensive Determination of the Hinode/EIS Roll Angle Authors: Pelouze, Gabriel; Auchère, Frédéric; Bocchialini, Karine; Harra, Louise; Baker, Deborah; Warren, Harry P.; Brooks, David H.; Mariska, John T. Bibcode: 2019SoPh..294...59P Altcode: 2019arXiv190311923P We present a new coalignment method for the EUV Imaging Spectrometer (EIS) on board the Hinode spacecraft. In addition to the pointing offset and spacecraft jitter, this method determines the roll angle of the instrument, which has never been systematically measured, and which is therefore usually not corrected. The optimal pointing for EIS is computed by maximizing the cross-correlations of the Fe XII 195.119 Å line with images from the 193 Å band of the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory (SDO). By coaligning 3336 rasters with high signal-to-noise ratio, we estimate the rotation angle between EIS and AIA and explore the distribution of its values. We report an average value of (−0.387±0.007 ) ∘. We also provide a software implementation of this method that can be used to coalign any EIS raster. Title: Comparison of Scattering Polarization Signals Observed by CLASP: Possible Indication of the Hanle Effect Authors: Ishikawa, R.; Trujillo Bueno, J.; Uitenbroek, H.; Kubo, M.; Tsuneta, S.; Goto, M.; Kano, R.; Narukage, N.; Bando, T.; Katsukawa, Y.; Ishikawa, S.; Giono, G.; Suematsu, Y.; Hara, H.; Shimizu, T.; Sakao, T.; Winebarger, A.; Kobayashi, K.; Cirtain, J.; Champey, P.; Auchère, F.; Štěpán, J.; Belluzzi, L.; Asensio Ramos, A.; Manso Sainz, R.; De Pomtieu, B.; Ichimoto, K.; Carlsson, M.; Casini, R. Bibcode: 2019ASPC..526..305I Altcode: The Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP; Kano et al. 2012; Kobayashi et al. 2012; Kubo et al. 2014) observed, for the first time, the linear polarization produced by scattering processes in the hydrogen Lyman-α (121.57 nm) and Si III (120.56 nm) lines of the solar disk radiation. The complexity of the observed scattering polarization (i.e., conspicuous spatial variations in Q/I and U/I at spatial scales of 10″-20″ and the absence of center-to- limb variation at the Lyman-α center; see Kano et al. 2017) motivated us to search for possible hints of the operation of the Hanle effect by comparing: (a) the Lyman-α line center signal, for which the critical field strength (BH) for the onset of the Hanle effect is 53 G, (b) the Lyman-α wing, which is insensitive to the Hanle effect, and (c) the Si III line, whose BH = 290 G. We focus on four regions with different total unsigned photospheric magnetic fluxes (estimated from SDO/HMI observations), and compare the corresponding U/I spatial variations in the Lyman-α wing, Lyman-α center, and Si III line. The U/I signal in the Lyman-α wing shows an antisymmetric spatial distribution, which is caused by the presence of a bright structure in all the selected regions, regardless of the total unsigned photospheric magnetic flux. In an internetwork region, the Lyman-α center shows an antisymmetric spatial variation across the selected bright structure, but it does not show it in other more magnetized regions. In the Si III line, the spatial variation of U/I deviates from the above-mentioned antisymmetric shape as the total unsigned photospheric magnetic flux increases. We argue that a plausible explanation of this differential behavior is the operation of the Hanle effect.

This work, presented in an oral contribution at this Workshop, has been published on The Astrophysical Journal (Ishikawa et al. 2017). Title: Solar data, dataproducts, and tools at MEDOC Authors: Buchlin, Eric; Caminade, Stéphane; Dufourg, Nicolas; Auchère, Frédéric; Baudin, Frédéric; Bocchialini, Karine; Boumier, Patrick; Janvier, Miho; Parenti, Susanna; Alingery, Pablo; Ballans, Hervé; Chane-Yook, Martine; Dexet, Marc; Mercier, Claude; Poulleau, Gilles Bibcode: 2019EGUGA..2117362B Altcode: MEDOC (Multi-Experiment Data and Operation Centre), initially created as a European data and operation centre for the SOHO mission, has grown with data from other solar physics space missions, from STEREO to SDO. Derived data products such as DEM maps from SDO/AIA, synoptic EUV intensity maps from SOHO/EIT, and catalogues of solar structures are also automatically produced and redistributed. Both the data and the derived data products are publicly available from web interfaces and from programmatic interfaces (with clients for IDL and Python), allowing classical data analysis as well as automatic queries, data download, and processing to be made on large datasets. Title: Groupe de Travail Soleil Heliosphere-Magnetospheres (SHM) Authors: Auchère, F.; Astafyeva, E.; Baudin, F.; Bourdarie, S.; Briand, C.; Brun, S.; Célestin, S.; Génot, V.; Kretzschmar, M.; Leblanc, F.; Rouillard, A.; Sahraoui, F. Bibcode: 2019shm..rept....1A Altcode: Les grandes questions scientifiques abordées dans le cadre de la thématique Soleil Héliosphère et Magnétosphères (SHM) couvrent l'ensemble des problématiques liées aux relations entre notre étoile et le système solaire. Cela commence par l'étude de la structure interne du Soleil à travers l'observation multi-spectrales, l'hélio-sismologie et la modélisation ; par l'étude de l'origine de la couronne solaire, son chauffage et l'accélération du vent solaire et des particules énergétiques solaires lors d'événements énergétiques solaires ; et enfin par l'étude de la propagation du vent solaire et des mécanismes de chauffage de celui-ci par dissipation turbulente. Title: The EUI instrument onboard Solar Orbiter: the EUV corona imaged differently Authors: Berghmans, David; Rochus, Pierre; Auchère, Frédéric; Harra, Louise; Schmutz, Werner; Schühle, Udo Bibcode: 2018csc..confE..73B Altcode: The ESA Solar Orbiter mission is designed to determine how the Sun creates and controls the heliosphere. The spacecraft will bring a combination of in situ and remote sensing instruments out of the ecliptic (>30°) and close to the sun (0.3 solar-radii). The launch of Solar Orbiter is expected (not earlier than) Feb 2019. The Extreme Ultraviolet Imager is part of the remote-sensing package of Solar Orbiter, to be operating during 3 ten-day periods of each orbit around the Sun, which last roughly half a year. These 3 periods will correspond to perihelion and maximal solar latitude north and south. The Extreme Ultraviolet Imager is itself a suite of three UV and EUV telescopes that observe the solar atmosphere both globally as well as at very high resolution. The two high-resolution imagers (HRIs) will image the solar atmosphere in the chromospheric Lyman alpha line and the coronal 17nm pass band with a resolution of 0.5 arcsec. From perihelion, this will correspond to a pixel footprint on the solar disc of (110km)^2 . The Full Sun Imager (FSI), working at the 17.4 nm and 30.4 nm EUV passbands, will provide a global view of the solar atmosphere and is therefore an essential building block for the "connection science" of the Solar Orbiter mission. The FSI field of view is large enough (228arcmin) that, even at perihelion and at maximal off-points by Solar Orbiter, the full solar disk remains in the field of view. This large FOV and the FSI's high sensitivity will allow to image the "transition corona" where the topology of streamers and pseudo-streamers fades in the solar wind. Furthermore, FSI will be the first to image all this from out of the ecliptic. In this talk we will give an overview of the EUI instrument. We will focus on the novel aspects of EUI that will allow it to image beyond what previous EUV imagers could show us: EUV imaging from the highest solar latitude, with the widest field-of-view and at highest spatial resolution. Title: The Coronal Monsoon: Thermal Nonequilibrium Revealed by Periodic Coronal Rain Authors: Auchère, Frédéric; Froment, Clara; Soubrié, Elie; Antolin, Patrick; Oliver, Ramon; Pelouze, Gabriel; Voyeux, Alfred Bibcode: 2018csc..confE.114A Altcode: We report on the discovery of periodic coronal rain in an off-limb sequence of SDO/AIA images. The showers are co-spatial and in phase with periodic (6.6 hr) intensity pulsations of coronal loops of the sort described by Auchère et al. (2014) and Froment et al. (2015, 2017. These new observations make possible a unified description of both phenomena. Coronal rain and periodic intensity pulsations of loops are two manifestations of the same physical process: evaporation / condensation cycles resulting from a state of thermal nonequilibrium (TNE). The fluctuations around coronal temperatures produce the intensity pulsations of loops, and rain falls along their legs if thermal runaway cools the periodic condensations down and below transition-region (TR)temperatures. This scenario is in line with the predictions of numerical models of quasi-steadily and footpoint heated loops. This event of periodic coronal rain is compared with a similar event showing only pulsations at coronal temperatures but no significant cool rain fall. For both events we have stereoscopic observations from the SDO and STEREO spacecraft which allows reconstruction of the 3D loop geometries. Comparison with numerical simulations suggest that these two events correspond to two regimes of TNE: one with "full condensations" (coronal rain) and another in which "incomplete condensations" start to develop but are pushed down one loop leg before they can reach chromospheric temperatures. These new observations impose severe constrains on the spatio-temporal distribution of coronal heating. Title: CLASP Constraints on the Magnetization and Geometrical Complexity of the Chromosphere-Corona Transition Region Authors: Trujillo Bueno, J.; Štěpán, J.; Belluzzi, L.; Asensio Ramos, A.; Manso Sainz, R.; del Pino Alemán, T.; Casini, R.; Ishikawa, R.; Kano, R.; Winebarger, A.; Auchère, F.; Narukage, N.; Kobayashi, K.; Bando, T.; Katsukawa, Y.; Kubo, M.; Ishikawa, S.; Giono, G.; Hara, H.; Suematsu, Y.; Shimizu, T.; Sakao, T.; Tsuneta, S.; Ichimoto, K.; Cirtain, J.; Champey, P.; De Pontieu, B.; Carlsson, M. Bibcode: 2018ApJ...866L..15T Altcode: 2018arXiv180908865T The Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP) is a suborbital rocket experiment that on 2015 September 3 measured the linear polarization produced by scattering processes in the hydrogen Lyα line of the solar disk radiation. The line-center photons of this spectral line radiation mostly stem from the chromosphere-corona transition region (TR). These unprecedented spectropolarimetric observations revealed an interesting surprise, namely that there is practically no center-to-limb variation (CLV) in the Q/I line-center signals. Using an analytical model, we first show that the geometric complexity of the corrugated surface that delineates the TR has a crucial impact on the CLV of the Q/I and U/I line-center signals. Second, we introduce a statistical description of the solar atmosphere based on a 3D model derived from a state-of-the-art radiation magnetohydrodynamic simulation. Each realization of the statistical ensemble is a 3D model characterized by a given degree of magnetization and corrugation of the TR, and for each such realization we solve the full 3D radiative transfer problem taking into account the impact of the CLASP instrument degradation on the calculated polarization signals. Finally, we apply the statistical inference method presented in a previous paper to show that the TR of the 3D model that produces the best agreement with the CLASP observations has a relatively weak magnetic field and a relatively high degree of corrugation. We emphasize that a suitable way to validate or refute numerical models of the upper solar chromosphere is by confronting calculations and observations of the scattering polarization in ultraviolet lines sensitive to the Hanle effect. Title: A Statistical Inference Method for Interpreting the CLASP Observations Authors: Štěpán, J.; Trujillo Bueno, J.; Belluzzi, L.; Asensio Ramos, A.; Manso Sainz, R.; del Pino Alemán, T.; Casini, R.; Kano, R.; Winebarger, A.; Auchère, F.; Ishikawa, R.; Narukage, N.; Kobayashi, K.; Bando, T.; Katsukawa, Y.; Kubo, M.; Ishikawa, S.; Giono, G.; Hara, H.; Suematsu, Y.; Shimizu, T.; Sakao, T.; Tsuneta, S.; Ichimoto, K.; Cirtain, J.; Champey, P.; De Pontieu, B.; Carlsson, M. Bibcode: 2018ApJ...865...48S Altcode: 2018arXiv180802725S On 2015 September 3, the Chromospheric Lyman-Alpha SpectroPolarimeter (CLASP) successfully measured the linear polarization produced by scattering processes in the hydrogen Lyα line of the solar disk radiation, revealing conspicuous spatial variations in the Q/I and U/I signals. Via the Hanle effect, the line-center Q/I and U/I amplitudes encode information on the magnetic field of the chromosphere-corona transition region, but they are also sensitive to the three-dimensional structure of this corrugated interface region. With the help of a simple line-formation model, here we propose a statistical inference method for interpreting the Lyα line-center polarization observed by CLASP. Title: Current State of UV Spectro-Polarimetry and its Future Direction Authors: Ishikawa, Ryohko; Sakao, Taro; Katsukawa, Yukio; Hara, Hirohisa; Ichimoto, Kiyoshi; Shimizu, Toshifumi; Kubo, Masahito; Auchere, Frederic; De Pontieu, Bart; Winebarger, Amy; Kobayashi, . Ken; Kano, Ryouhei; Narukage, Noriyuki; Trujillo Bueno, Javier; Song, Dong-uk; Manso Sainz, Rafael; Asensio Ramos, Andres; Leenaarts, Jorritt; Carlsson, Mats; Bando, Takamasa; Ishikawa, Shin-nosuke; Tsuneta, Saku; Belluzzi, Luca; Suematsu, Yoshinori; Giono, Gabriel; Yoshida, Masaki; Goto, Motoshi; Del Pino Aleman, Tanausu; Stepan, Jiri; Okamoto, Joten; Tsuzuki, Toshihiro; Uraguchi, Fumihiro; Champey, Patrick; Alsina Ballester, Ernest; Casini, Roberto; McKenzie, David; Rachmeler, Laurel; Bethge, Christian Bibcode: 2018cosp...42E1564I Altcode: To obtain quantitative information on the magnetic field in low beta regions (i.e., upper chromosphere and above) has been increasingly important to understand the energetic phenomena of the outer solar atmosphere such as flare, coronal heating, and the solar wind acceleration. In the UV range, there are abundant spectral lines that originate in the upper chromosphere and transition region. However, the Zeeman effect in these spectral lines does not give rise to easily measurable polarization signals because of the weak magnetic field strength and the larger Doppler broadening compared with the Zeeman effect. Instead, the Hanle effect in UV lines is expected to be a suitable diagnostic tool of the magnetic field in the upper atmospheric layers. To investigate the validity of UV spectro-polarimetry and the Hanle effect, the Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP), which is a NASA sounding- rocket experiment, was launched at White Sands in US on September 3, 2015. During its 5 minutes ballistic flight, it successfully performed spectro-polarimetric observations of the hydrogen Lyman-alpha line (121.57 nm) with an unprecedentedly high polarization sensitivity of 0.1% in this wavelength range. CLASP observed the linear polarization produced by scattering process in VUV lines for the first time and detected the polarization signals which indicate the operation of the Hanle effect. Following the success of CLASP, we are confident that UV spectro-polarimetry is the way to proceed, and we are planning the second flight of CLASP (CLASP2: Chromospheric LAyer SpectroPolarimeter 2). For this second flight we will carry out spectro-polarimetry in the Mg II h and k lines around 280 nm, with minimum modifications of the CLASP1 instrument. The linear polarization in the Mg II k line is induced by scattering processes and the Hanle effect, being sensitive to magnetic field strengths of 5 to 50 G. In addition, the circular polarizations in the Mg II h and k lines induced by the Zeeman effect can be measurable in at least plage and active regions. The combination of the Hanle and Zeeman effects could help us to more reliably infer the magnetic fields of the upper solar chromosphere. CLASP2 was selected for flight and is being developed for launch in the spring of 2019.Based on these sounding rocket experiments (CLASP1 and 2), we aim at establishing the strategy and refining the instrument concept for future space missions to explore the enigmatic atmospheric layers via UV spectro-polarimetry. Title: Wavefront error measurements and alignment of CLASP2 telescope with a dual-band pass cold mirror coated primary mirror Authors: Yoshida, Masaki; Song, Donguk; Ishikawa, Ryoko; Kano, Ryouhei; Katsukawa, Yukio; Suematsu, Yoshinori; Narukage, Noriyuki; Kubo, Masahito; Shinoda, Kazuya; Okamoto, Takenori J.; McKenzie, David E.; Rachmeler, Laurel A.; Auchère, Frédéric; Trujillo Bueno, Javier Bibcode: 2018SPIE10699E..30Y Altcode: "Chromospheric LAyer Spectro-Polarimeter (CLASP2)" is the next sounding rocket experiment of the "Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP)" that succeeded in observing for the first time the linear polarization spectra in the hydrogen Lyman-α line (121.6 nm) and is scheduled to be launched in 2019. In CLASP2, we will carry out full Stokes-vector spectropolarimetric observations in the Mg ii h and k lines near 280 nm with the spectro-polarimeter (SP), while imaging observations in the Lyman-α line will be conducted with the slitjaw optics (SJ). For the wavelength selection of CLASP2, the primary mirror of the telescope uses a new dual-band pass cold mirror coating targeting both at 121.6 nm and 280 nm. Therefore, we have to perform again the alignment of the telescope after the installation of the recoated primary mirror. Before unmounting the primary mirror from the telescope structure, we measured the wave-front error (WFE) of the telescope. The measured WFE map was consistent with what we had before the CLASP flight, clearly indicating that the telescope alignment has been maintained even after the flight. After the re-coated primary mirror was installed the WFE was measured, and coma aberration was found to be larger. Finally, the secondary mirror shim adjustments were carried out based on the WFE measurements. In CLASP2 telescope, we improved a fitting method of WFE map (applying 8th terms circular Zernike polynomial fitting instead of 37th terms circular Zernike fitting) and the improved method enables to achieve better performance than CLASP telescope. Indeed, WFE map obtained after the final shim adjustment indicated that the required specification (< 5.5 μm RMS spot radius) that is more stringent than CLASP telescope was met. Title: Optical alignment of the high-precision UV spectro-polarimeter (CLASP2) Authors: Song, Donguk; Ishikawa, Ryohko; Kano, Ryouhei; Yoshida, Masaki; Tsuzuki, Toshihiro; Uraguchi, Fumihiro; Shinoda, Kazuya; Hara, Hirohisa; Okamoto, Takenori J.; Auchère, Frédéric; McKenzie, David E.; Rachmeler, Laurel A.; Trujillo Bueno, Javier Bibcode: 2018SPIE10699E..2WS Altcode: Chromospheric LAyer Spectro-Polarimeter (CLASP2) is our next sounding rocket experiment after the success of Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP1). CLASP2 is scheduled to launch in 2019, and aims to achieve high precision measurements (< 0.1 %) of the linear and circular polarizations in the Mg ii h and k lines near the 280 nm, whose line cores originate in the upper solar chromosphere. The CLASP2 spectro-polarimeter follows very successful design concept of the CLASP1 instrument with the minimal modification. A new grating was fabricated with the same radius of curvature as the CLASP1 grating, but with a different ruling density. This allows us to essentially reuse the CLASP1 mechanical structures and layout of the optics. However, because the observing wavelength of CLASP2 is twice longer than that of CLASP1, a magnifier optical system was newly added in front of the cameras to double the focal length of CLASP2 and to maintain the same wavelength resolution as CLASP1 (0.01 nm). Meanwhile, a careful optical alignment of the spectro-polarimeter is required to reach the 0.01 nm wavelength resolution. Therefore, we established an efficient alignment procedure for the CLASP2 spectro-polarimeter based on an experience of CLASP1. Here, we explain in detail the methods for achieving the optical alignment of the CLASP2 spectro-polarimeter and discuss our results by comparing with the performance requirements. Title: The Coronal Monsoon: Thermal Nonequilibrium Revealed by Periodic Coronal Rain Authors: Auchere, Frederic; Soubrie, Elie; Antolin, Patrick; Froment, Clara; Oliver, Ramon; Pelouze, Gabriel Bibcode: 2018cosp...42E.144A Altcode: We report on the discovery of periodic coronal rain in an off-limb sequence of SDO/AIA images. The showers are co-spatial and in phase with periodic (6.6 hr) intensity pulsations of coronal loops of the sort described by Auchère et al. (2014) and Froment et al. (2015, 2017}. These new observations make possible a unified description of both phenomena. Coronal rain and periodic intensity pulsations of loops are two manifestations of the same physical process: evaporation / condensation cycles resulting from a state of thermal nonequilibrium (TNE). The fluctuations around coronal temperatures produce the intensity pulsations of loops, and rain falls along their legs if thermal runaway cools the periodic condensations down and below transition-region (TR) temperatures. This scenario is in line with the predictions of numerical models of quasi-steadily and footpoint heated loops.This event of periodic coronal rain is compared with a similar event showing only pulsations at coronal temperatures but no significant cool rain fall. For both events we have stereoscopic observations from the SDO and STEREO spacecraft which allows reconstruction of the 3D loop geometries. Comparison with numerical simulations suggest that these two events correspond to two regimes of TNE: one with "full condensations" (coronal rain) and another in which "incomplete condensations" start to develop but are pushed down one loop leg before they can reach chromospheric temperatures.These new observations impose severe constrains on the spatio-temporal distribution of coronal heating. Title: Prospects for coronal magnetic field measurements from space Authors: Auchere, Frederic Bibcode: 2018cosp...42E.143A Altcode: Despite its fundamental importance as a driver for the physics of the Sun and of the helio-sphere, the magnetic field of our star's outer atmosphere remains poorly understood. This is due in large part to the fact that the magnetic field is a very dfficult quantity to measure. Our knowledge of its strength and orientation is largely based on extrapolations from photospheric observations, not from direct measurements. These extrapolations require strong assumptions on critical but unobserved quantities and thus fail to accurately reproduce the complex topologies inferred from remote-sensing observations of coronal structures in white light, EUV, and X-rays. Direct measurements of the coronal magnetic field are clearly identified by the international heliophysics community as a key element in the understanding of our star.In the past ten years, reliable ground based coronal magnetic field measurements have emerged. However, these measurements wil always be limited by the difficulty to observe the corona from the ground. Much like routine coronagraphic observations from space by SOHO/LASCO haverevolutionized our knowledge of the solar corona, space based polarimetric observations are expected to lead to major breakthroughs. In this perspective, we will review the past and future projects of space missions designed to measure the coronal magnetic field from space. Title: Search for predicted periodic flows in loops undergoing thermal non-equilibrium Authors: Pelouze, Gabriel; Parenti, Susanna; Bocchialini, Karine; Soubrie, Elie; Auchere, Frederic; Froment, Clara Bibcode: 2018cosp...42E2623P Altcode: Long-period intensity pulsations have been recently detected in coronal loopswith EUV images of both SoHO/EIT (Auchère et al., 2014) and SDO/AIA (Froment etal., 2015). These pulsations have been interpreted as resulting from thermalnon-equilibrium (TNE), thus providing a signature of a highly-stratified andquasi-constant heating at the loops footpoints (Froment et al., 2017; Auchèreet al., 2016). Depending on the adequacy between the geometry of the loop andthe characteristics of the heating, this can result in either complete (atchromospheric temperatures) or incomplete (> 1 MK) condensation and evaporationcycles, that are responsible for the observed intensity pulsations. Using 1Dhydrodynamic simulations, Froment et al. (2017) were able to reproduce theobserved pulsations, with incomplete condensation for the active region studiedin their previous paper. The simulations also predict periodic plasma flowsalong the loops footpoints, with velocities up to 40 km/s. We try to detect these flows by using time series of spatially resolved spectrafrom the EUV spectrometer Hinode/EIS. We systematically search for EIS datasetsthat correspond to the observation of pulsation events among the 3000+ thatwere detected in AIA data, between 2010 and 2016. For the 9 datasets that arefound, we derive series of Doppler velocity maps, which allows us to track theevolution of the plasma velocity in the loop over several pulsation periods. Wethen compare these data to the results of previous simulations andobservations. However the expected pulsations in velocity cannot be identifiedin any of the datasets that we analysed. We demonstrate that line of sightambiguities, combined with low signal to noise ratio or lack of time cadence,can explain this non-detection. Title: The EUI flight instrument of Solar Orbiter: from optical alignment to end-to-end calibration Authors: Halain, J. -P.; Renotte, E.; Auchère, F.; Berghmans, D.; Delmotte, F.; Harra, L.; Schmutz, W.; Schühle, U.; Aznar Cuadrado, R.; Dumesnil, C.; Gyo, M.; Kennedy, T.; Verbeeck, C.; Barbay, J.; Giordanengo, B.; Gissot, S.; Gottwald, A.; Heerlein, K.; Hellin, M. -L.; Hermans, A.; Hervier, V.; Jacques, L.; Laubis, C.; Mazzoli, A.; Meining, S.; Mercier, R.; Philippon, A.; Roose, S.; Rossi, L.; Scholze, F.; Smith, P.; Teriaca, L.; Zhang, X.; Rochus, P. Bibcode: 2018SPIE10699E..0HH Altcode: The Extreme Ultraviolet Imager (EUI) instrument for the Solar Orbiter mission will image the solar corona in the extreme ultraviolet (17.1 nm and 30.4 nm) and in the vacuum ultraviolet (121.6 nm) spectral ranges. The development of the EUI instrument has been successfully completed with the optical alignment of its three channels' telescope, the thermal and mechanical environmental verification, the electrical and software validations, and an end-toend on-ground calibration of the two-units' flight instrument at the operating wavelengths. The instrument has been delivered and installed on the Solar Orbiter spacecraft, which is now undergoing all preparatory activities before launch. Title: On the Occurrence of Thermal Nonequilibrium in Coronal Loops Authors: Froment, C.; Auchère, F.; Mikić, Z.; Aulanier, G.; Bocchialini, K.; Buchlin, E.; Solomon, J.; Soubrié, E. Bibcode: 2018ApJ...855...52F Altcode: 2018arXiv180204010F Long-period EUV pulsations, recently discovered to be common in active regions, are understood to be the coronal manifestation of thermal nonequilibrium (TNE). The active regions previously studied with EIT/Solar and Heliospheric Observatory and AIA/SDO indicated that long-period intensity pulsations are localized in only one or two loop bundles. The basic idea of this study is to understand why. For this purpose, we tested the response of different loop systems, using different magnetic configurations, to different stratifications and strengths of the heating. We present an extensive parameter-space study using 1D hydrodynamic simulations (1020 in total) and conclude that the occurrence of TNE requires specific combinations of parameters. Our study shows that the TNE cycles are confined to specific ranges in parameter space. This naturally explains why only some loops undergo constant periodic pulsations over several days: since the loop geometry and the heating properties generally vary from one loop to another in an active region, only the ones in which these parameters are compatible exhibit TNE cycles. Furthermore, these parameters (heating and geometry) are likely to vary significantly over the duration of a cycle, which potentially limits the possibilities of periodic behavior. This study also confirms that long-period intensity pulsations and coronal rain are two aspects of the same phenomenon: both phenomena can occur for similar heating conditions and can appear simultaneously in the simulations. Title: The Coronal Monsoon: Thermal Nonequilibrium Revealed by Periodic Coronal Rain Authors: Auchère, Frédéric; Froment, Clara; Soubrié, Elie; Antolin, Patrick; Oliver, Ramon; Pelouze, Gabriel Bibcode: 2018ApJ...853..176A Altcode: 2018arXiv180201852A We report on the discovery of periodic coronal rain in an off-limb sequence of Solar Dynamics Observatory/Atmospheric Imaging Assembly images. The showers are co-spatial and in phase with periodic (6.6 hr) intensity pulsations of coronal loops of the sort described by Auchère et al. and Froment et al. These new observations make possible a unified description of both phenomena. Coronal rain and periodic intensity pulsations of loops are two manifestations of the same physical process: evaporation/condensation cycles resulting from a state of thermal nonequilibrium. The fluctuations around coronal temperatures produce the intensity pulsations of loops, and rain falls along their legs if thermal runaway cools the periodic condensations down and below transition-region temperatures. This scenario is in line with the predictions of numerical models of quasi-steadily and footpoint heated loops. The presence of coronal rain—albeit non-periodic—in several other structures within the studied field of view implies that this type of heating is at play on a large scale. Title: EUV high resolution imager on-board solar orbiter: optical design and detector performances Authors: Halain, J. P.; Mazzoli, A.; Rochus, P.; Renotte, E.; Stockman, Y.; Berghmans, D.; BenMoussa, A.; Auchère, F. Bibcode: 2017SPIE10564E..3VH Altcode: The EUV high resolution imager (HRI) channel of the Extreme Ultraviolet Imager (EUI) on-board Solar Orbiter will observe the solar atmospheric layers at 17.4 nm wavelength with a 200 km resolution. The HRI channel is based on a compact two mirrors off-axis design. The spectral selection is obtained by a multilayer coating deposited on the mirrors and by redundant Aluminum filters rejecting the visible and infrared light. The detector is a 2k x 2k array back-thinned silicon CMOS-APS with 10 μm pixel pitch, sensitive in the EUV wavelength range. Due to the instrument compactness and the constraints on the optical design, the channel performance is very sensitive to the manufacturing, alignments and settling errors. A trade-off between two optical layouts was therefore performed to select the final optical design and to improve the mirror mounts. The effect of diffraction by the filter mesh support and by the mirror diffusion has been included in the overall error budget. Manufacturing of mirror and mounts has started and will result in thermo-mechanical validation on the EUI instrument structural and thermal model (STM). Because of the limited channel entrance aperture and consequently the low input flux, the channel performance also relies on the detector EUV sensitivity, readout noise and dynamic range. Based on the characterization of a CMOS-APS back-side detector prototype, showing promising results, the EUI detector has been specified and is under development. These detectors will undergo a qualification program before being tested and integrated on the EUI instrument. Title: Comparison of Solar Fine Structure Observed Simultaneously in Lyα and Mg II h Authors: Schmit, D.; Sukhorukov, A. V.; De Pontieu, B.; Leenaarts, J.; Bethge, C.; Winebarger, A.; Auchère, F.; Bando, T.; Ishikawa, R.; Kano, R.; Kobayashi, K.; Narukage, N.; Trujillo Bueno, J. Bibcode: 2017ApJ...847..141S Altcode: 2017arXiv170900035S The Chromospheric Lyman Alpha Spectropolarimeter (CLASP) observed the Sun in H I Lyα during a suborbital rocket flight on 2015 September 3. The Interface Region Imaging Telescope (IRIS) coordinated with the CLASP observations and recorded nearly simultaneous and co-spatial observations in the Mg II h and k lines. The Mg II h and Lyα lines are important transitions, energetically and diagnostically, in the chromosphere. The canonical solar atmosphere model predicts that these lines form in close proximity to each other and so we expect that the line profiles will exhibit similar variability. In this analysis, we present these coordinated observations and discuss how the two profiles compare over a region of quiet Sun at viewing angles that approach the limb. In addition to the observations, we synthesize both line profiles using a 3D radiation-MHD simulation. In the observations, we find that the peak width and the peak intensities are well correlated between the lines. For the simulation, we do not find the same relationship. We have attempted to mitigate the instrumental differences between IRIS and CLASP and to reproduce the instrumental factors in the synthetic profiles. The model indicates that formation heights of the lines differ in a somewhat regular fashion related to magnetic geometry. This variation explains to some degree the lack of correlation, observed and synthesized, between Mg II and Lyα. Our analysis will aid in the definition of future observatories that aim to link dynamics in the chromosphere and transition region. Title: CLASP/SJ Observations of Rapid Time Variations in the Lyα Emission in a Solar Active Region Authors: Ishikawa, Shin-nosuke; Kubo, Masahito; Katsukawa, Yukio; Kano, Ryouhei; Narukage, Noriyuki; Ishikawa, Ryohko; Bando, Takamasa; Winebarger, Amy; Kobayashi, Ken; Trujillo Bueno, Javier; Auchère, Frédéric Bibcode: 2017ApJ...846..127I Altcode: The Chromospheric Lyα SpectroPolarimeter (CLASP) is a sounding rocket experiment launched on 2015 September 3 to investigate the solar chromosphere and transition region. The slit-jaw (SJ) optical system captured Lyα images with a high time cadence of 0.6 s. From the CLASP/SJ observations, many variations in the solar chromosphere and transition region emission with a timescale of <1 minute were discovered. In this paper, we focus on the active region within the SJ field of view and investigate the relationship between short (<30 s) temporal variations in the Lyα emission and the coronal structures observed by Solar Dynamics Observatory/Atmospheric Imaging Assembly (AIA). We compare the Lyα temporal variations at the coronal loop footpoints observed in the AIA 211 Å (≈2 MK) and AIA 171 Å (≈0.6 MK) channels with those in the regions with bright Lyα features without a clear association with the coronal loop footpoints. We find more short (<30 s) temporal variations in the Lyα intensity in the footpoint regions. Those variations did not depend on the temperature of the coronal loops. Therefore, the temporal variations in the Lyα intensity at this timescale range could be related to the heating of the coronal structures up to temperatures around the sensitivity peak of 171 Å. No signature was found to support the scenario that these Lyα intensity variations were related to the nanoflares. Waves or jets from the lower layers (lower chromosphere or photosphere) are possible causes for this phenomenon. Title: The VUV instrument SPICE for Solar Orbiter: performance ground testing Authors: Caldwell, Martin E.; Morris, Nigel; Griffin, Douglas K.; Eccleston, Paul; Anderson, Mark; Pastor Santos, Carmen; Bruzzi, Davide; Tustain, Samuel; Howe, Chris; Davenne, Jenny; Grundy, Timothy; Speight, Roisin; Sidher, Sunil D.; Giunta, Alessandra; Fludra, Andrzej; Philippon, Anne; Auchere, Frederic; Hassler, Don; Davila, Joseph M.; Thompson, William T.; Schuehle, Udo H.; Meining, Stefan; Walls, Buddy; Phelan, P.; Dunn, Greg; Klein, Roman M.; Reichel, Thomas; Gyo, Manfred; Munro, Grant J.; Holmes, William; Doyle, Peter Bibcode: 2017SPIE10397E..08C Altcode: SPICE is an imaging spectrometer operating at vacuum ultraviolet (VUV) wavelengths, 70.4 - 79.0 nm and 97.3 - 104.9 nm. It is a facility instrument on the Solar Orbiter mission, which carries 10 science instruments in all, to make observations of the Sun's atmosphere and heliosphere, at close proximity to the Sun, i.e to 0.28 A.U. at perihelion. SPICE's role is to make VUV measurements of plasma in the solar atmosphere. SPICE is designed to achieve spectral imaging at spectral resolution >1500, spatial resolution of several arcsec, and two-dimensional FOV of 11 x16arcmins. The many strong constraints on the instrument design imposed by the mission requirements prevent the imaging performance from exceeding those of previous instruments, but by being closer to the sun there is a gain in spatial resolution. The price which is paid is the harsher environment, particularly thermal. This leads to some novel features in the design, which needed to be proven by ground test programs. These include a dichroic solar-transmitting primary mirror to dump the solar heat, a high in-flight temperature (60deg.C) and gradients in the optics box, and a bespoke variable-line-spacing grating to minimise the number of reflective components used. The tests culminate in the systemlevel test of VUV imaging performance and pointing stability. We will describe how our dedicated facility with heritage from previous solar instruments, is used to make these tests, and show the results, firstly on the Engineering Model of the optics unit, and more recently on the Flight Model. For the keywords, select up to 8 key terms for a search on your manuscript's subject. Title: CLASP2: The Chromospheric LAyer Spectro-Polarimeter Authors: Rachmeler, Laurel; E McKenzie, David; Ishikawa, Ryohko; Trujillo Bueno, Javier; Auchère, Frédéric; Kobayashi, Ken; Winebarger, Amy; Bethge, Christian; Kano, Ryouhei; Kubo, Masahito; Song, Donguk; Narukage, Noriyuki; Ishikawa, Shin-nosuke; De Pontieu, Bart; Carlsson, Mats; Yoshida, Masaki; Belluzzi, Luca; Stepan, Jiri; del Pino Alemná, Tanausú; Ballester, Ernest Alsina; Asensio Ramos, Andres Bibcode: 2017SPD....4811010R Altcode: We present the instrument, science case, and timeline of the CLASP2 sounding rocket mission. The successful CLASP (Chromospheric Lyman-Alpha Spectro-Polarimeter) sounding rocket flight in 2015 resulted in the first-ever linear polarization measurements of solar hydrogen Lyman-alpha line, which is sensitive to the Hanle effect and can be used to constrain the magnetic field and geometric complexity of the upper chromosphere. Ly-alpha is one of several upper chromospheric lines that contain magnetic information. In the spring of 2019, we will re-fly the modified CLASP telescope to measure the full Stokes profile of Mg II h & k near 280 nm. This set of lines is sensitive to the upper chromospheric magnetic field via both the Hanle and the Zeeman effects. Title: CLASP2: The Chromospheric LAyer Spectro-Polarimeter Authors: Rachmeler, Laurel A.; McKenzie, D. E.; Ishikawa, R.; Trujillo-Bueno, J.; Auchere, F.; Kobayashi, K.; Winebarger, A.; Bethge, C.; Kano, R.; Kubo, M.; Song, D.; Narukage, N.; Ishikawa, S.; De Pontieu, B.; Carlsson, M.; Yoshida, M.; Belluzzi, L.; Stepan, J.; del Pino Alemán, T.; Alsina Ballester, E.; Asensio Ramos, A. Bibcode: 2017shin.confE..79R Altcode: We present the instrument, science case, and timeline of the CLASP2 sounding rocket mission. The successful CLASP (Chromospheric Lyman-Alpha Spectro-Polarimeter) sounding rocket flight in 2015 resulted in the first-ever linear polarization measurements of solar hydrogen Lyman-alpha line, which is sensitive to the Hanle effect and can be used to constrain the magnetic field and geometric complexity of the upper chromosphere. Ly-alpha is one of several upper chromospheric lines that contain magnetic information. In the spring of 2019, we will re-fly the modified CLASP telescope to measure the full Stokes profile of Mg II h & k near 280 nm. This set of lines is sensitive to the upper chromospheric magnetic field via both the Hanle and the Zeeman effects. Title: SOLARIS: Solar Sail Investigation of the Sun Authors: Appourchaux, Thierry; Auchère, Frédéric; Antonucci, Ester; Gizon, Laurent; MacDonald, Malcolm; Hara, Hirohisa; Sekii, Takashi; Moses, Daniel; Vourlidas, Angelos Bibcode: 2017arXiv170708193A Altcode: In this paper, we detail the scientific objectives and outline a strawman payload of the SOLAR sail Investigation of the Sun (SOLARIS). The science objectives are to study the 3D structure of the solar magnetic and velocity field, the variation of total solar irradiance with latitude, and the structure of the corona. We show how we can meet these science objective using solar-sail technologies currently under development. We provide a tentative mission profile considering several trade-off approaches. We also provide a tentative mass budget breakdown and a perspective for a programmatic implementation. Title: Indication of the Hanle Effect by Comparing the Scattering Polarization Observed by CLASP in the Lyα and Si III 120.65 nm Lines Authors: Ishikawa, R.; Trujillo Bueno, J.; Uitenbroek, H.; Kubo, M.; Tsuneta, S.; Goto, M.; Kano, R.; Narukage, N.; Bando, T.; Katsukawa, Y.; Ishikawa, S.; Giono, G.; Suematsu, Y.; Hara, H.; Shimizu, T.; Sakao, T.; Winebarger, A.; Kobayashi, K.; Cirtain, J.; Champey, P.; Auchère, F.; Štěpán, J.; Belluzzi, L.; Asensio Ramos, A.; Manso Sainz, R.; De Pontieu, B.; Ichimoto, K.; Carlsson, M.; Casini, R. Bibcode: 2017ApJ...841...31I Altcode: The Chromospheric Lyman-Alpha Spectro-Polarimeter is a sounding rocket experiment that has provided the first successful measurement of the linear polarization produced by scattering processes in the hydrogen Lyα line (121.57 nm) radiation of the solar disk. In this paper, we report that the Si III line at 120.65 nm also shows scattering polarization and we compare the scattering polarization signals observed in the Lyα and Si III lines in order to search for observational signatures of the Hanle effect. We focus on four selected bright structures and investigate how the U/I spatial variations vary between the Lyα wing, the Lyα core, and the Si III line as a function of the total unsigned photospheric magnetic flux estimated from Solar Dynamics Observatory/Helioseismic and Magnetic Imager observations. In an internetwork region, the Lyα core shows an antisymmetric spatial variation across the selected bright structure, but it does not show it in other more magnetized regions. In the Si III line, the spatial variation of U/I deviates from the above-mentioned antisymmetric shape as the total unsigned photospheric magnetic flux increases. A plausible explanation of this difference is the operation of the Hanle effect. We argue that diagnostic techniques based on the scattering polarization observed simultaneously in two spectral lines with very different sensitivities to the Hanle effect, like Lyα and Si III, are of great potential interest for exploring the magnetism of the upper solar chromosphere and transition region. Title: Erratum: “On the Fourier and Wavelet Analysis of Coronal Time Series” (2016, ApJ, 825, 110) Authors: Auchère, F.; Froment, C.; Bocchialini, K.; Buchlin, E.; Solomon, J. Bibcode: 2017ApJ...838..166A Altcode: No abstract at ADS Title: Polarization Calibration of the Chromospheric Lyman-Alpha SpectroPolarimeter for a 0.1% Polarization Sensitivity in the VUV Range. Part II: In-Flight Calibration Authors: Giono, G.; Ishikawa, R.; Narukage, N.; Kano, R.; Katsukawa, Y.; Kubo, M.; Ishikawa, S.; Bando, T.; Hara, H.; Suematsu, Y.; Winebarger, A.; Kobayashi, K.; Auchère, F.; Trujillo Bueno, J.; Tsuneta, S.; Shimizu, T.; Sakao, T.; Cirtain, J.; Champey, P.; Asensio Ramos, A.; Štěpán, J.; Belluzzi, L.; Manso Sainz, R.; De Pontieu, B.; Ichimoto, K.; Carlsson, M.; Casini, R.; Goto, M. Bibcode: 2017SoPh..292...57G Altcode: The Chromospheric Lyman-Alpha SpectroPolarimeter is a sounding rocket instrument designed to measure for the first time the linear polarization of the hydrogen Lyman-α line (121.6 nm). The instrument was successfully launched on 3 September 2015 and observations were conducted at the solar disc center and close to the limb during the five-minutes flight. In this article, the disc center observations are used to provide an in-flight calibration of the instrument spurious polarization. The derived in-flight spurious polarization is consistent with the spurious polarization levels determined during the pre-flight calibration and a statistical analysis of the polarization fluctuations from solar origin is conducted to ensure a 0.014% precision on the spurious polarization. The combination of the pre-flight and the in-flight polarization calibrations provides a complete picture of the instrument response matrix, and a proper error transfer method is used to confirm the achieved polarization accuracy. As a result, the unprecedented 0.1% polarization accuracy of the instrument in the vacuum ultraviolet is ensured by the polarization calibration. Title: Discovery of Scattering Polarization in the Hydrogen Lyα Line of the Solar Disk Radiation Authors: Kano, R.; Trujillo Bueno, J.; Winebarger, A.; Auchère, F.; Narukage, N.; Ishikawa, R.; Kobayashi, K.; Bando, T.; Katsukawa, Y.; Kubo, M.; Ishikawa, S.; Giono, G.; Hara, H.; Suematsu, Y.; Shimizu, T.; Sakao, T.; Tsuneta, S.; Ichimoto, K.; Goto, M.; Belluzzi, L.; Štěpán, J.; Asensio Ramos, A.; Manso Sainz, R.; Champey, P.; Cirtain, J.; De Pontieu, B.; Casini, R.; Carlsson, M. Bibcode: 2017ApJ...839L..10K Altcode: 2017arXiv170403228K There is a thin transition region (TR) in the solar atmosphere where the temperature rises from 10,000 K in the chromosphere to millions of degrees in the corona. Little is known about the mechanisms that dominate this enigmatic region other than the magnetic field plays a key role. The magnetism of the TR can only be detected by polarimetric measurements of a few ultraviolet (UV) spectral lines, the Lyα line of neutral hydrogen at 121.6 nm (the strongest line of the solar UV spectrum) being of particular interest given its sensitivity to the Hanle effect (the magnetic-field-induced modification of the scattering line polarization). We report the discovery of linear polarization produced by scattering processes in the Lyα line, obtained with the Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP) rocket experiment. The Stokes profiles observed by CLASP in quiet regions of the solar disk show that the Q/I and U/I linear polarization signals are of the order of 0.1% in the line core and up to a few percent in the nearby wings, and that both have conspicuous spatial variations with scales of ∼10 arcsec. These observations help constrain theoretical models of the chromosphere-corona TR and extrapolations of the magnetic field from photospheric magnetograms. In fact, the observed spatial variation from disk to limb of polarization at the line core and wings already challenge the predictions from three-dimensional magnetohydrodynamical models of the upper solar chromosphere. Title: High-Reflectivity Coatings for a Vacuum Ultraviolet Spectropolarimeter Authors: Narukage, Noriyuki; Kubo, Masahito; Ishikawa, Ryohko; Ishikawa, Shin-nosuke; Katsukawa, Yukio; Kobiki, Toshihiko; Giono, Gabriel; Kano, Ryouhei; Bando, Takamasa; Tsuneta, Saku; Auchère, Frédéric; Kobayashi, Ken; Winebarger, Amy; McCandless, Jim; Chen, Jianrong; Choi, Joanne Bibcode: 2017SoPh..292...40N Altcode: Precise polarization measurements in the vacuum ultraviolet (VUV) region are expected to be a new tool for inferring the magnetic fields in the upper atmosphere of the Sun. High-reflectivity coatings are key elements to achieving high-throughput optics for precise polarization measurements. We fabricated three types of high-reflectivity coatings for a solar spectropolarimeter in the hydrogen Lyman-α (Lyα ; 121.567 nm) region and evaluated their performance. The first high-reflectivity mirror coating offers a reflectivity of more than 80 % in Lyα optics. The second is a reflective narrow-band filter coating that has a peak reflectivity of 57 % in Lyα , whereas its reflectivity in the visible light range is lower than 1/10 of the peak reflectivity (∼5 % on average). This coating can be used to easily realize a visible light rejection system, which is indispensable for a solar telescope, while maintaining high throughput in the Lyα line. The third is a high-efficiency reflective polarizing coating that almost exclusively reflects an s-polarized beam at its Brewster angle of 68° with a reflectivity of 55 %. This coating achieves both high polarizing power and high throughput. These coatings contributed to the high-throughput solar VUV spectropolarimeter called the Chromospheric Lyman-Alpha SpectroPolarimeter (CLASP), which was launched on 3 September, 2015. Title: Long-period Intensity Pulsations in Coronal Loops Explained by Thermal Non-equilibrium Cycles Authors: Froment, C.; Auchère, F.; Aulanier, G.; Mikić, Z.; Bocchialini, K.; Buchlin, E.; Solomon, J. Bibcode: 2017ApJ...835..272F Altcode: 2017arXiv170101309F In solar coronal loops, thermal non-equilibrium (TNE) is a phenomenon that can occur when the heating is both highly stratified and quasi-constant. Unambiguous observational identification of TNE would thus permit us to strongly constrain heating scenarios. While TNE is currently the standard interpretation of coronal rain, the long-term periodic evolution predicted by simulations has never been observed. However, the detection of long-period intensity pulsations (periods of several hours) has been recently reported with the Solar and Heliospheric Observatory/EIT, and this phenomenon appears to be very common in loops. Moreover, the three intensity-pulsation events that we recently studied with the Solar Dynamics Observatory/Atmospheric Imaging Assembly (AIA) show strong evidence for TNE in warm loops. In this paper, a realistic loop geometry from linear force-free field (LFFF) extrapolations is used as input to 1D hydrodynamic simulations. Our simulations show that, for the present loop geometry, the heating has to be asymmetrical to produce TNE. We analyze in detail one particular simulation that reproduces the average thermal behavior of one of the pulsating loop bundle observed with AIA. We compare the properties of this simulation with those deduced from the observations. The magnetic topology of the LFFF extrapolations points to the presence of sites of preferred reconnection at one footpoint, supporting the presence of asymmetric heating. In addition, we can reproduce the temporal large-scale intensity properties of the pulsating loops. This simulation further strengthens the interpretation of the observed pulsations as signatures of TNE. This consequently provides important information on the heating localization and timescale for these loops. Title: Polarization Calibration of the Chromospheric Lyman-Alpha SpectroPolarimeter for a 0.1 % Polarization Sensitivity in the VUV Range. Part I: Pre-flight Calibration Authors: Giono, G.; Ishikawa, R.; Narukage, N.; Kano, R.; Katsukawa, Y.; Kubo, M.; Ishikawa, S.; Bando, T.; Hara, H.; Suematsu, Y.; Winebarger, A.; Kobayashi, K.; Auchère, F.; Trujillo Bueno, J. Bibcode: 2016SoPh..291.3831G Altcode: 2016SoPh..tmp..177G The Chromospheric Lyman-Alpha SpectroPolarimeter (CLASP) is a sounding rocket experiment designed to measure for the first time the linear polarization of the hydrogen Lyman-α line (121.6 nm) and requires a 0.1 % polarization sensitivity, which is unprecedented for a spectropolarimeter in the vacuum UV (VUV) spectral range. Title: Discovery of Ubiquitous Fast-Propagating Intensity Disturbances by the Chromospheric Lyman Alpha Spectropolarimeter (CLASP) Authors: Kubo, M.; Katsukawa, Y.; Suematsu, Y.; Kano, R.; Bando, T.; Narukage, N.; Ishikawa, R.; Hara, H.; Giono, G.; Tsuneta, S.; Ishikawa, S.; Shimizu, T.; Sakao, T.; Winebarger, A.; Kobayashi, K.; Cirtain, J.; Champey, P.; Auchère, F.; Trujillo Bueno, J.; Asensio Ramos, A.; Štěpán, J.; Belluzzi, L.; Manso Sainz, R.; De Pontieu, B.; Ichimoto, K.; Carlsson, M.; Casini, R.; Goto, M. Bibcode: 2016ApJ...832..141K Altcode: High-cadence observations by the slit-jaw (SJ) optics system of the sounding rocket experiment known as the Chromospheric Lyman Alpha Spectropolarimeter (CLASP) reveal ubiquitous intensity disturbances that recurrently propagate in either the chromosphere or the transition region or both at a speed much higher than the speed of sound. The CLASP/SJ instrument provides a time series of two-dimensional images taken with broadband filters centered on the Lyα line at a 0.6 s cadence. The multiple fast-propagating intensity disturbances appear in the quiet Sun and in an active region, and they are clearly detected in at least 20 areas in a field of view of 527″ × 527″ during the 5 minute observing time. The apparent speeds of the intensity disturbances range from 150 to 350 km s-1, and they are comparable to the local Alfvén speed in the transition region. The intensity disturbances tend to propagate along bright elongated structures away from areas with strong photospheric magnetic fields. This suggests that the observed fast-propagating intensity disturbances are related to the magnetic canopy structures. The maximum distance traveled by the intensity disturbances is about 10″, and the widths are a few arcseconds, which are almost determined by a pixel size of 1.″03. The timescale of each intensity pulse is shorter than 30 s. One possible explanation for the fast-propagating intensity disturbances observed by CLASP is magnetohydrodynamic fast-mode waves. Title: Thermal Non-Equilibrium Revealed by Periodic Pulses of Random Amplitudes in Solar Coronal Loops Authors: Auchère, F.; Froment, C.; Bocchialini, K.; Buchlin, E.; Solomon, J. Bibcode: 2016usc..confE.131A Altcode: We recently detected variations in extreme ultraviolet intensity in coronal loops repeating with periods of several hours. Models of loops including stratified and quasi-steady heating predict the development of a state of thermal non-equilibrium (TNE): cycles of evaporative upflows at the footpoints followed by falling condensations at the apex. Based on Fourier and wavelet analysis, we demonstrate that the observed periodic signals are indeed not signatures of vibrational modes. Instead, superimposed on the power law expected from the stochastic background emission, the power spectra of the time series exhibit the discrete harmonics and continua expected from periodic trains of pulses of random amplitudes. These characteristics reinforce our earlier interpretation of these pulsations as being aborted TNE cycles. Title: Fourier and Wavelet Analysis of Coronal Time Series Authors: Auchère, F.; Froment, C.; Bocchialini, K.; Buchlin, E.; Solomon, J. Bibcode: 2016usc..confE.130A Altcode: Using Fourier and wavelet analysis, we critically re-assess the significance of our detection of periodic pulsations in coronal loops. We show that the proper identification of the frequency dependence and statistical properties of the different components of the power spectra provies a strong argument against the common practice of data detrending, which tends to produce spurious detections around the cut-off frequency of the filter. In addition, the white and red noise models built into the widely used wavelet code of Torrence & Compo cannot, in most cases, adequately represent the power spectra of coronal time series, thus also possibly causing false positives. Both effects suggest that several reports of periodic phenomena should be re-examined. The Torrence & Compo code nonetheless effectively computes rigorous confidence levels if provided with pertinent models of mean power spectra, and we describe the appropriate manner in which to call its core routines. We recall the meaning of the default confidence levels output from the code, and we propose new Monte-Carlo-derived levels that take into account the total number of degrees of freedom in the wavelet spectra. These improvements allow us to confirm that the power peaks that we detected have a very low probability of being caused by noise. Title: Long-period Intensity Pulsations as the Manifestation of the Heating Stratification and Timescale in Coronal Loops Authors: Froment, Clara; Auchère, Frédéric; Aulanier, Guillaume; Mikić, Zoran; Bocchialini, Karine; Buchlin, Eric; Solomon, Jacques Bibcode: 2016usc..confE..47F Altcode: In solar coronal loops, thermal non-equilibrium (TNE) is a phenomenon that can occur when the heating is both highly-stratified and quasi-constant. Unambiguous observational identification of TNE would thus permit to strongly constrain heating scenarios. Up to now, while TNE is the standard interpretation of coronal rain, it was not believed to happen commonly in warm coronal loops. Recently, the detection of long-period intensity pulsations (periods of several hours) has been reported with SoHO/EIT. This phenomenon appears to be very common in loops (Auchère et al. 2014). In Froment et al. 2015, three intensity-pulsation events studied with SDO/AIA, show strong evidence for TNE in warm loops. We use realistic loop geometries from LFFF extrapolations for one of these events are used as input to a 1D hydrodynamic simulation of TNE. A highly-stratified heating function is chosen to reproduce the observed period of pulsation and temperature of the loops. With these conditions, the heating function has to be asymmetric. The magnetic topology of the LFFF extrapolations points to the presence of sites of preferred reconnection at one footpoint, supporting the presence of asymmetric heating. We compared the properties of the simulated loop with the properties deduced from observations. We found that the 1D hydrodynamic simulation can reproduce the large temporal scale intensity properties of the pulsating loops (Froment et al. 2016, submitted). This simulation further strengthen the interpretation of the observed pulsations as signatures of TNE. This implies that the heating for these loops is highly-stratified and that the frequency of the heating events must be high compared to the typical cooling time. Title: GAIA-DEM: a database providing AIA/SDO DEM maps Authors: Guennou, C.; Auchère, F.; Bocchialini, F.; Soubrié, E.; Mercier, C.; Parenti, S.; Alingery, P. Bibcode: 2016usc..confE.108G Altcode: The Gaussian AIA DEm Maps (GAIA-DEM) database at MEDOC (IAS) provides through a simple and intuitive web interface DEM inversions of the SDO/AIA data, computed every 30min. The Gaussian approximation is used to describe the main features of the true DEM(log T) by its first moments. For each date, maps of the three Gaussian fit parameters (central temperature, total emission measure and Gaussian width) and of the chi^2 are available in FITS format. Users can preview the maps before downloading them. In addition, users can display the initial SDO/AIA images using Helioviewer, and query the database through webservices accessible from IDL and Python clients. This presentation is for the "Thermal Diagnostics with SDO/AIA" mini-workshop. Title: A small mission concept to the Sun-Earth Lagrangian L5 point for innovative solar, heliospheric and space weather science Authors: Lavraud, B.; Liu, Y.; Segura, K.; He, J.; Qin, G.; Temmer, M.; Vial, J. -C.; Xiong, M.; Davies, J. A.; Rouillard, A. P.; Pinto, R.; Auchère, F.; Harrison, R. A.; Eyles, C.; Gan, W.; Lamy, P.; Xia, L.; Eastwood, J. P.; Kong, L.; Wang, J.; Wimmer-Schweingruber, R. F.; Zhang, S.; Zong, Q.; Soucek, J.; An, J.; Prech, L.; Zhang, A.; Rochus, P.; Bothmer, V.; Janvier, M.; Maksimovic, M.; Escoubet, C. P.; Kilpua, E. K. J.; Tappin, J.; Vainio, R.; Poedts, S.; Dunlop, M. W.; Savani, N.; Gopalswamy, N.; Bale, S. D.; Li, G.; Howard, T.; DeForest, C.; Webb, D.; Lugaz, N.; Fuselier, S. A.; Dalmasse, K.; Tallineau, J.; Vranken, D.; Fernández, J. G. Bibcode: 2016JASTP.146..171L Altcode: We present a concept for a small mission to the Sun-Earth Lagrangian L5 point for innovative solar, heliospheric and space weather science. The proposed INvestigation of Solar-Terrestrial Activity aNd Transients (INSTANT) mission is designed to identify how solar coronal magnetic fields drive eruptions, mass transport and particle acceleration that impact the Earth and the heliosphere. INSTANT is the first mission designed to (1) obtain measurements of coronal magnetic fields from space and (2) determine coronal mass ejection (CME) kinematics with unparalleled accuracy. Thanks to innovative instrumentation at a vantage point that provides the most suitable perspective view of the Sun-Earth system, INSTANT would uniquely track the whole chain of fundamental processes driving space weather at Earth. We present the science requirements, payload and mission profile that fulfill ambitious science objectives within small mission programmatic boundary conditions. Title: Thermal Non-equilibrium Revealed by Periodic Pulses of Random Amplitudes in Solar Coronal Loops Authors: Auchère, F.; Froment, C.; Bocchialini, K.; Buchlin, E.; Solomon, J. Bibcode: 2016ApJ...827..152A Altcode: 2016arXiv160803789A We recently detected variations in extreme ultraviolet intensity in coronal loops repeating with periods of several hours. Models of loops including stratified and quasi-steady heating predict the development of a state of thermal non-equilibrium (TNE): cycles of evaporative upflows at the footpoints followed by falling condensations at the apex. Based on Fourier and wavelet analysis, we demonstrate that the observed periodic signals are indeed not signatures of vibrational modes. Instead, superimposed on the power law expected from the stochastic background emission, the power spectra of the time series exhibit the discrete harmonics and continua expected from periodic trains of pulses of random amplitudes. These characteristics reinforce our earlier interpretation of these pulsations as being aborted TNE cycles. Title: The qualification campaign of the EUI instrument of Solar Orbiter Authors: Halain, J. -P.; Rochus, P.; Renotte, E.; Hermans, A.; Jacques, L.; Mazzoli, A.; Auchère, F.; Berghmans, D.; Harra, L.; Schühle, U.; Schmutz, W.; Aznar Cuadrado, R.; Dumesnil, C.; Gyo, M.; Kennedy, T.; Verbeeck, C.; Smith, P. Bibcode: 2016SPIE.9905E..2XH Altcode: The Extreme Ultraviolet Imager (EUI) instrument is one of the ten scientific instruments on board the Solar Orbiter mission to be launched in October 2018. It will provide full-sun and high-resolution images of the solar corona in the extreme ultraviolet (17.1 nm and 30.4 nm) and in the vacuum ultraviolet (121.6 nm). The validation of the EUI instrument design has been completed with the Assembly, Integration and Test (AIT) of the instrument two-units Qualification Model (QM). Optical, electrical, electro-magnetic compatibility, thermal and mechanical environmental verifications were conducted and are summarized here. The integration and test procedures for the Flight Model (FM) instrument and sub-systems were also verified. Following the Qualification Review, the flight instrument activities were started with the assembly of the flight units. The mechanical and thermal acceptance tests and an end-to-end final calibration in the (E)UV will then be conducted before delivery for integration on the Solar Orbiter Spacecraft by end of 2016. Title: The SPICE Spectral Imager on Solar Orbiter: Linking the Sun to the Heliosphere Authors: Fludra, Andrzej; Haberreiter, Margit; Peter, Hardi; Vial, Jean-Claude; Harrison, Richard; Parenti, Susanna; Innes, Davina; Schmutz, Werner; Buchlin, Eric; Chamberlin, Phillip; Thompson, William; Gabriel, Alan; Morris, Nigel; Caldwell, Martin; Auchere, Frederic; Curdt, Werner; Teriaca, Luca; Hassler, Donald M.; DeForest, Craig; Hansteen, Viggo; Carlsson, Mats; Philippon, Anne; Janvier, Miho; Wimmer-Schweingruber, Robert; Griffin, Douglas; Davila, Joseph; Giunta, Alessandra; Waltham, Nick; Eccleston, Paul; Gottwald, Alexander; Klein, Roman; Hanley, John; Walls, Buddy; Howe, Chris; Schuehle, Udo Bibcode: 2016cosp...41E.607F Altcode: The SPICE (Spectral Imaging of the Coronal Environment) instrument is one of the key remote sensing instruments onboard the upcoming Solar Orbiter Mission. SPICE has been designed to contribute to the science goals of the mission by investigating the source regions of outflows and ejection processes which link the solar surface and corona to the heliosphere. In particular, SPICE will provide quantitative information on the physical state and composition of the solar atmosphere plasma. For example, SPICE will access relative abundances of ions to study the origin and the spatial/temporal variations of the 'First Ionization Potential effect', which are key signatures to trace the solar wind and plasma ejections paths within the heliosphere. Here we will present the instrument and its performance capability to attain the scientific requirements. We will also discuss how different observation modes can be chosen to obtain the best science results during the different orbits of the mission. To maximize the scientific return of the instrument, the SPICE team is working to optimize the instrument operations, and to facilitate the data access and their exploitation. Title: Optical alignment of the Chromospheric Lyman-Alpha Spectro-Polarimeter using sophisticated methods to minimize activities under vacuum Authors: Giono, G.; Katsukawa, Y.; Ishikawa, R.; Narukage, N.; Kano, R.; Kubo, M.; Ishikawa, S.; Bando, T.; Hara, H.; Suematsu, Y.; Winebarger, A.; Kobayashi, K.; Auchère, F.; Trujillo Bueno, J. Bibcode: 2016SPIE.9905E..3DG Altcode: The Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP) is a sounding-rocket instrument developed at the National Astronomical Observatory of Japan (NAOJ) as a part of an international collaboration. The instrument main scientific goal is to achieve polarization measurement of the Lyman-α line at 121.56 nm emitted from the solar upper-chromosphere and transition region with an unprecedented 0.1% accuracy. The optics are composed of a Cassegrain telescope coated with a "cold mirror" coating optimized for UV reflection and a dual-channel spectrograph allowing for simultaneous observation of the two orthogonal states of polarization. Although the polarization sensitivity is the most important aspect of the instrument, the spatial and spectral resolutions of the instrument are also crucial to observe the chromospheric features and resolve the Ly-α profiles. A precise alignment of the optics is required to ensure the resolutions, but experiments under vacuum conditions are needed since Ly-α is absorbed by air, making the alignment experiments difficult. To bypass this issue, we developed methods to align the telescope and the spectrograph separately in visible light. We explain these methods and present the results for the optical alignment of the CLASP telescope and spectrograph. We then discuss the combined performances of both parts to derive the expected resolutions of the instrument, and compare them with the flight observations performed on September 3rd 2015. Title: Solar abundances with the SPICE spectral imager on Solar Orbiter Authors: Giunta, Alessandra; Haberreiter, Margit; Peter, Hardi; Vial, Jean-Claude; Harrison, Richard; Parenti, Susanna; Innes, Davina; Schmutz, Werner; Buchlin, Eric; Chamberlin, Phillip; Thompson, William; Bocchialini, Karine; Gabriel, Alan; Morris, Nigel; Caldwell, Martin; Auchere, Frederic; Curdt, Werner; Teriaca, Luca; Hassler, Donald M.; DeForest, Craig; Hansteen, Viggo; Carlsson, Mats; Philippon, Anne; Janvier, Miho; Wimmer-Schweingruber, Robert; Griffin, Douglas; Baudin, Frederic; Davila, Joseph; Fludra, Andrzej; Waltham, Nick; Eccleston, Paul; Gottwald, Alexander; Klein, Roman; Hanley, John; Walls, Buddy; Howe, Chris; Schuehle, Udo; Gyo, Manfred; Pfiffner, Dany Bibcode: 2016cosp...41E.681G Altcode: Elemental composition of the solar atmosphere and in particular abundance bias of low and high First Ionization Potential (FIP) elements are a key tracer of the source regions of the solar wind. These abundances and their spatio-temporal variations, as well as the other plasma parameters , will be derived by the SPICE (Spectral Imaging of the Coronal Environment) EUV spectral imager on the upcoming Solar Orbiter mission. SPICE is designed to provide spectroheliograms (spectral images) using a core set of emission lines arising from ions of both low-FIP and high-FIP elements. These lines are formed over a wide range of temperatures, enabling the analysis of the different layers of the solar atmosphere. SPICE will use these spectroheliograms to produce dynamic composition maps of the solar atmosphere to be compared to in-situ measurements of the solar wind composition of the same elements (i.e. O, Ne, Mg, Fe). This will provide a tool to study the connectivity between the spacecraft (the Heliosphere) and the Sun. We will discuss the SPICE capabilities for such composition measurements. Title: On the Fourier and Wavelet Analysis of Coronal Time Series Authors: Auchère, F.; Froment, C.; Bocchialini, K.; Buchlin, E.; Solomon, J. Bibcode: 2016ApJ...825..110A Altcode: 2016arXiv160605251A Using Fourier and wavelet analysis, we critically re-assess the significance of our detection of periodic pulsations in coronal loops. We show that the proper identification of the frequency dependence and statistical properties of the different components of the power spectra provides a strong argument against the common practice of data detrending, which tends to produce spurious detections around the cut-off frequency of the filter. In addition, the white and red noise models built into the widely used wavelet code of Torrence & Compo cannot, in most cases, adequately represent the power spectra of coronal time series, thus also possibly causing false positives. Both effects suggest that several reports of periodic phenomena should be re-examined. The Torrence & Compo code nonetheless effectively computes rigorous confidence levels if provided with pertinent models of mean power spectra, and we describe the appropriate manner in which to call its core routines. We recall the meaning of the default confidence levels output from the code, and we propose new Monte-Carlo-derived levels that take into account the total number of degrees of freedom in the wavelet spectra. These improvements allow us to confirm that the power peaks that we detected have a very low probability of being caused by noise. Title: Chromospheric LAyer SpectroPolarimeter (CLASP2) Authors: Narukage, Noriyuki; McKenzie, David E.; Ishikawa, Ryoko; Trujillo-Bueno, Javier; De Pontieu, Bart; Kubo, Masahito; Ishikawa, Shin-nosuke; Kano, Ryouhei; Suematsu, Yoshinori; Yoshida, Masaki; Rachmeler, Laurel A.; Kobayashi, Ken; Cirtain, Jonathan W.; Winebarger, Amy R.; Asensio Ramos, Andres; del Pino Aleman, Tanausu; Štępán, Jiri; Belluzzi, Luca; Larruquert, Juan Ignacio; Auchère, Frédéric; Leenaarts, Jorrit; Carlsson, Mattias J. L. Bibcode: 2016SPIE.9905E..08N Altcode: The sounding rocket Chromospheric Lyman-Alpha SpectroPolarimeter (CLASP) was launched on September 3rd, 2015, and successfully detected (with a polarization accuracy of 0.1 %) the linear polarization signals (Stokes Q and U) that scattering processes were predicted to produce in the hydrogen Lyman-alpha line (Lyα 121.567 nm). Via the Hanle effect, this unique data set may provide novel information about the magnetic structure and energetics in the upper solar chromosphere. The CLASP instrument was safely recovered without any damage and we have recently proposed to dedicate its second flight to observe the four Stokes profiles in the spectral region of the Mg II h and k lines around 280 nm; in these lines the polarization signals result from scattering processes and the Hanle and Zeeman effects. Here we describe the modifications needed to develop this new instrument called the "Chromospheric LAyer SpectroPolarimeter" (CLASP2). Title: Lifecycle of a large-scale polar coronal pseudostreamer/cavity system Authors: Guennou, Chloé; Auchere, Frederic; Seaton, Daniel; Rachmeler, Laurel Bibcode: 2016cosp...41E.749G Altcode: Coronal cavities, tunnel-like areas of rarefied density, provide important information about the magnetic structures that support prominences. The magnetic energy is stored through the twisted or shared magnetic field, ultimately released through Coronal Mass Ejections (CME). To be able to forecast these energetic releases of material and prevent potential terrestrial consequences, the understanding of the cavity 3D morphology, magnetic and thermal properties are essential. The prominences embedded in the cavity only trace a small part of the magnetic field, whereas the much larger cavity provides more information about the magnetic field morphology. As a result, a clear understanding of the coronal volume of the cavity significantly advances our understanding of both the pre-eruption equilibrium and the triggers of such eruptions. Determining both morphological and thermodynamical coronal structures is difficult due to the optically thin nature of the plasma. Observations are subject to integration along the line-of-sight (LOS). This effect can strongly complicate both the derivation and the interpretation of important physical quantities. One way to deduce the 3D structure is with Solar Rotational Tomography (SRT). The 3D plasma emissivity is estimated from EUV/white light images taken from different viewpoints. Physical properties can be then derived using Differential Emission Measure analysis from multi-wavelength 3D reconstructions. We applied this technique to an exceptional large-scale coronal pseudostreamer/cavity system in the southern polar region of the solar corona that was visible for approximately a year starting in February 2014. It is unusual to see such a large closed-field structure embedded within the open polar coronal hole. We investigate this structure to document its formation, evolution and eventually its shrinking process using data from both the PROBA2/SWAP and SDO/AIA EUV imagers. We found that the cavity temperature is extremely stable with time and is essentially at a similar or slightly hotter temperature than the surrounding pseudostreamer. Two regimes in cavity thermal properties were observed: during the first 5 months of observation, we found lower density depletion and highly multi-thermal plasma, while after the pseudostreamer became stable and slowly shrank, the depletion was more pronounced and the plasma was less multithermal. As the thermodynamic properties are strongly correlated with the magnetic structure, these results provide constraints on both the trigger of CMEs and the processes that maintain cavities stability for such a long lifetime. Title: Tracking a large pseudostreamer to pinpoint the southern polar magnetic field reversal Authors: Rachmeler, Laurel; Guennou, Chloé; Seaton, Daniel B.; Gibson, Sarah; Auchère, Frédéric Bibcode: 2016SPD....4740104R Altcode: The reversal of the solar polar magnetic field is notoriously hard to pin down due to the extreme viewing angle of the pole. In Cycle 24, the southern polar field reversal can be pinpointed with high accuracy due to a large-scale pseudostreamer that formed over the pole and persisted for approximately a year. We tracked the size and shape of this structure with multiple observations and analysis techniques including PROBA2/SWAP EUV images, AIA EUV images, CoMP data, and 3D tomographic reconstructions. We find that the heliospheric field reversed polarity in February 2014, whereas in the photosphere the last vestiges of the previous polar field polarity remained until March 2015. Title: Lifecycle of a large-scale polar coronal pseudostreamer/cavity system Authors: Guennou, Chloé; Rachmeler, Laurel; Seaton, Daniel; Auchère, Frédéric Bibcode: 2016FrASS...3...14G Altcode: We report on an exceptional large-scale coronal pseudostreamer/cavity system in the southern polar region of the solar corona that was visible for approximately a year starting in February 2014. It is unusual to see such a large closed-field structure embedded within the open polar coronal hole. We investigate this structure to document its formation, evolution and eventually its shrinking process using data from both the PROBA2/SWAP and SDO/AIA EUV imagers. In particular, we used EUV tomography to find the overall shape and internal structure of the pseudostreamer and to determine its 3D temperature and density structure using DEM analysis. We found that the cavity temperature is extremely stable with time and is essentially at a similar or slightly hotter temperature than the surrounding pseudostreamer. Two regimes in cavity thermal properties were observed: during the first 5 months of observation, we found lower density depletion and highly multi-thermal plasma, while after the pseudostreamer became stable and slowly shrank, the depletion was more pronounced and the plasma was less multithermal. As the thermodynamic properties are strongly correlated with the magnetic structure, these results provide constraints on both the trigger of CMEs and the processes that maintain cavities stability for such a long lifetime. Title: Spectro-polarimetric observation in UV with CLASP to probe the chromosphere and transition region Authors: Kano, Ryouhei; Ishikawa, Ryohko; Winebarger, Amy R.; Auchère, Frédéric; Trujillo Bueno, Javier; Narukage, Noriyuki; Kobayashi, Ken; Bando, Takamasa; Katsukawa, Yukio; Kubo, Masahito; Ishikawa, Shin-Nosuke; Giono, Gabriel; Hara, Hirohisa; Suematsu, Yoshinori; Shimizu, Toshifumi; Sakao, Taro; Tsuneta, Saku; Ichimoto, Kiyoshi; Goto, Motoshi; Cirtain, Jonathan W.; De Pontieu, Bart; Casini, Roberto; Manso Sainz, Rafael; Asensio Ramos, Andres; Stepan, Jiri; Belluzzi, Luca; Carlsson, Mats Bibcode: 2016SPD....4710107K Altcode: The Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP) is a NASA sounding-rocket experiment that was performed in White Sands in the US on September 3, 2015. During its 5-minute ballistic flight, CLASP successfully made the first spectro-polarimetric observation in the Lyman-alpha line (121.57 nm) originating in the chromosphere and transition region. Since the Lyman-alpha polarization is sensitive to magnetic field of 10-100 G by the Hanle effect, we aim to infer the magnetic field information in such upper solar atmosphere with this experiment.The obtained CLASP data showed that the Lyman-alpha scattering polarization is about a few percent in the wings and the order of 0.1% in the core near the solar limb, as it had been theoretically predicted, and that both polarization signals have a conspicuous spatio-temporal variability. CLASP also observed another upper-chromospheric line, Si III (120.65 nm), whose critical field strength for the Hanle effect is 290 G, and showed a measurable scattering polarization of a few % in this line. The polarization properties of the Si III line could facilitate the interpretation of the scattering polarization observed in the Lyman-alpha line.In this presentation, we would like to show how the upper chromosphere and transition region are seen in the polarization of these UV lines and discuss the possible source of these complicated polarization signals. Title: Waves and Magnetism in the Solar Atmosphere (WAMIS) Authors: Ko, Yuan-Kuen; Moses, John; Laming, John; Strachan, Leonard; Tun Beltran, Samuel; Tomczyk, Steven; Gibson, Sarah; Auchere, Frederic; Casini, Roberto; Fineschi, Silvano; Knoelker, Michael; Korendyke, Clarence; McIntosh, Scott; Romoli, Marco; Rybak, Jan; Socker, Dennis; Vourlidas, Angelos; Wu, Qian Bibcode: 2016FrASS...3....1K Altcode: Comprehensive measurements of magnetic fields in the solar corona have a long history as an important scientific goal. Besides being crucial to understanding coronal structures and the Sun’s generation of space weather, direct measurements of their strength and direction are also crucial steps in understanding observed wave motions. In this regard, the remote sensing instrumentation used to make coronal magnetic field measurements is well suited to measuring the Doppler signature of waves in the solar structures. In this paper, we describe the design and scientific values of the Waves and Magnetism in the Solar Atmosphere (WAMIS) investigation. WAMIS, taking advantage of greatly improved infrared filters and detectors, forward models, advanced diagnostic tools and inversion codes, is a long-duration high-altitude balloon payload designed to obtain a breakthrough in the measurement of coronal magnetic fields and in advancing the understanding of the interaction of these fields with space plasmas. It consists of a 20 cm aperture coronagraph with a visible-IR spectro-polarimeter focal plane assembly. The balloon altitude would provide minimum sky background and atmospheric scattering at the wavelengths in which these observations are made. It would also enable continuous measurements of the strength and direction of coronal magnetic fields without interruptions from the day-night cycle and weather. These measurements will be made over a large field-of-view allowing one to distinguish the magnetic signatures of different coronal structures, and at the spatial and temporal resolutions required to address outstanding problems in coronal physics. Additionally, WAMIS could obtain near simultaneous observations of the electron scattered K-corona for context and to obtain the electron density. These comprehensive observations are not provided by any current single ground-based or space observatory. The fundamental advancements achieved by the near-space observations of WAMIS on coronal field would point the way for future ground based and orbital instrumentation. Title: Waves and Magnetism in the Solar Atmosphere (WAMIS) Authors: Strachan, L.; Ko, Y. -K.; Moses, J. D.; Laming, J. M.; Auchere, F.; Casini, R.; Fineschi, S.; Gibson, S.; Knoelker, M.; Korendyke, C.; Mcintosh, S.; Romoli, M.; Rybak, J.; Socker, D.; Tomczyk, S.; Vourlidas, A.; Wu, Q. Bibcode: 2015IAUS..305..121S Altcode: Magnetic fields in the solar atmosphere provide the energy for most varieties of solar activity, including high-energy electromagnetic radiation, solar energetic particles, flares, and coronal mass ejections, as well as powering the solar wind. Despite the fundamental role of magnetic fields in solar and heliospheric physics, there exist only very limited measurements of the field above the base of the corona. What is needed are direct measurements of not only the strength and orientation of the magnetic field but also the signatures of wave motions in order to better understand coronal structure, solar activity, and the role of MHD waves in heating and accelerating the solar wind. Fortunately, the remote sensing instrumentation used to make magnetic field measurements is also well suited to measure the Doppler signature of waves in the solar structures. We present here a mission concept for the Waves And Magnetism In the Solar Atmosphere (WAMIS) experiment which is proposed for a NASA long-duration balloon flight. Title: The extreme ultraviolet imager of solar orbiter: optical design and alignment scheme Authors: Halain, J. -P.; Mazzoli, A.; Meining, S.; Rochus, P.; Renotte, E.; Auchère, F.; Schühle, U.; Delmotte, F.; Dumesnil, C.; Philippon, A.; Mercier, R.; Hermans, A. Bibcode: 2015SPIE.9604E..0HH Altcode: The Extreme Ultraviolet Imager (EUI) is one of the remote sensing instruments on-board the Solar Orbiter mission. It will provide dual-band full-Sun images of the solar corona in the extreme ultraviolet (17.1 nm and 30.4 nm), and high resolution images of the solar disk in both extreme ultraviolet (17.1 nm) and vacuum ultraviolet (Lyman-alpha 121.6 nm). The EUI optical design takes heritage of previous similar instruments. The Full Sun Imager (FSI) channel is a single mirror Herschel design telescope. The two High Resolution Imager (HRI) channels are based on a two-mirror optical refractive scheme, one Ritchey-Chretien and one Gregory optical design for the EUV and the Lyman-alpha channels, respectively. The spectral performances of the EUI channels are obtained thanks to dedicated mirror multilayer coatings and specific band-pass filters. The FSI channel uses a dual-band mirror coating combined with aluminum and zirconium band-pass filters. The HRI channels use optimized band-pass selection mirror coatings combined with aluminum band-pass filters and narrow band interference filters for Lyman-alpha. The optical performances result from accurate mirror manufacturing tolerances and from a two-step alignment procedure. The primary mirrors are first co-aligned. The HRI secondary mirrors and focal planes positions are then adjusted to have an optimum interferometric cavity in each of these two channels. For that purpose a dedicated alignment test setup has been prepared, composed of a dummy focal plane assembly representing the detector position. Before the alignment on the flight optical bench, the overall alignment method has been validated on the Structural and Thermal Model, on a dummy bench using flight spare optics, then on the Qualification Model to be used for the system verification test and qualifications. Title: The extreme UV imager telescope on-board the Solar Orbiter mission: overview of phase C and D Authors: Halain, J. -P.; Rochus, P.; Renotte, E.; Hermans, A.; Jacques, L.; Auchère, F.; Berghmans, D.; Harra, L.; Schühle, U.; Schmutz, W.; Zhukov, A.; Aznar Cuadrado, R.; Delmotte, F.; Dumesnil, C.; Gyo, M.; Kennedy, T.; Smith, P.; Tandy, J.; Mercier, R.; Verbeeck, C. Bibcode: 2015SPIE.9604E..0GH Altcode: The Solar Orbiter mission is composed of ten scientific instruments dedicated to the observation of the Sun's atmosphere and its heliosphere, taking advantage of an out-of ecliptic orbit and at perihelion reaching a proximity close to 0.28 A.U. On board Solar Orbiter, the Extreme Ultraviolet Imager (EUI) will provide full-Sun image sequences of the solar corona in the extreme ultraviolet (17.1 nm and 30.4 nm), and high-resolution image sequences of the solar disk in the extreme ultraviolet (17.1 nm) and in the vacuum ultraviolet (121.6 nm). The EUI concept uses heritage from previous similar extreme ultraviolet instrument. Additional constraints from the specific orbit (thermal and radiation environment, limited telemetry download) however required dedicated technologies to achieve the scientific objectives of the mission. The development phase C of the instrument and its sub-systems has been successfully completed, including thermomechanical and electrical design validations with the Structural Thermal Model (STM) and the Engineering Model (EM). The instrument STM and EM units have been integrated on the respective spacecraft models and will undergo the system level tests. In parallel, the Phase D has been started with the sub-system qualifications and the flight parts manufacturing. The next steps of the EUI development will be the instrument Qualification Model (QM) integration and qualification tests. The Flight Model (FM) instrument activities will then follow with the acceptance tests and calibration campaigns. Title: CLASP: A UV Spectropolarimeter on a Sounding Rocket for Probing theChromosphere-Corona Transition Regio Authors: Ishikawa, Ryohko; Kano, Ryouhei; Winebarger, Amy; Auchere, Frederic; Trujillo Bueno, Javier; Bando, Takamasa; Narukage, Noriyuki; Kobayashi, Ken; Katsukawa, Yukio; Kubo, Masahito; Ishikawa, Shin-nosuke; Giono, Gabriel; Tsuneta, Saku; Hara, Hirohisa; Suematsu, Yoshinori; Shimizu, Toshifumi; Sakao, Taro; Ichimoto, Kiyoshi; Cirtain, Jonathan; De Pontieu, Bart; Casini, Roberto; Manso Sainz, Rafael; Asensio Ramos, Andres; Stepan, Jiri; Belluzzi, Luca Bibcode: 2015IAUGA..2254536I Altcode: The wish to understand the energetic phenomena of the outer solar atmosphere makes it increasingly important to achieve quantitative information on the magnetic field in the chromosphere-corona transition region. To this end, we need to measure and model the linear polarization produced by scattering processes and the Hanle effect in strong UV resonance lines, such as the hydrogen Lyman-alpha line. A team consisting of Japan, USA, Spain, France, and Norway has been developing a sounding rocket experiment called the Chromospheric Lyman-alpha Spectro-Polarimeter (CLASP). The aim is to detect the scattering polarization produced by anisotropic radiation pumping in the hydrogen Lyman-alpha line (121.6 nm), and via the Hanle effect to try to constrain the magnetic field vector in the upper chromosphere and transition region. In this talk, we will present an overview of our CLASP mission, its scientific objectives, ground tests made, and the latest information on the launch planned for the Summer of 2015. Title: Probing Solar Cycle 24's southern polar field reversal with a pseudostreamer Authors: Rachmeler, Laurel A.; Guennou, Chloe; Seaton, Daniel; Auchère, Frédéric Bibcode: 2015shin.confE..65R Altcode: In Solar Cycle 24 the northern hemisphere reached activity maximum around late 2011, while the south has trailed by at least two years. The northern hemispheric polar field reversal has been fragmented and complicated by poleward surges of both polarities. The southern polar field, on the other hand, has progressed in a straightforward manner: the boundary between the old cycle's positive field and the new cycle's negative field has moved progressively southward. Determining when the polar field flips sign is a difficult task because the photospheric magnetic field at the poles is either poorly, or not at all, observed depending on the solar B-angle. Here, we report on a pseudostreamer that we observed at the southern pole for a year beginning in February 2014, and we use this feature to determine the southern polar field reversal. We tracked the formation, evolution, and disappearance of the pseudostreamer using limb identification and tomography with SWAP 17.4 nm EUV images. The pseudostreamer overlayed a roughly circular polarity inversion line at the photosphere; both the pseudostreamer and the inversion line gradually shrank as the new cycle's negative field moved poleward. Using the morphology of the pseudostreamer, we determined that the southern polar coronal field completely reversed in approximately March 2015. All of the field inside the pseudostreamer is closed field, including the former cycle's positive polar field. Thus the heliospheric field, which is composed of open structures, reversed polarity a year earlier, when the pseudostreamer first formed. Title: Evidence for Evaporation-incomplete Condensation Cycles in Warm Solar Coronal Loops Authors: Froment, C.; Auchère, F.; Bocchialini, K.; Buchlin, E.; Guennou, C.; Solomon, J. Bibcode: 2015ApJ...807..158F Altcode: 2015arXiv150408129F Quasi-constant heating at the footpoints of loops leads to evaporation and condensation cycles of the plasma: thermal non-equilibrium (TNE). This phenomenon is believed to play a role in the formation of prominences and coronal rain. However, it is often discounted as being involved in the heating of warm loops because the models do not reproduce observations. Recent simulations have shown that these inconsistencies with observations may be due to oversimplifications of the geometries of the models. In addition, our recent observations reveal that long-period intensity pulsations (several hours) are common in solar coronal loops. These periods are consistent with those expected from TNE. The aim of this paper is to derive characteristic physical properties of the plasma for some of these events to test the potential role of TNE in loop heating. We analyzed three events in detail using the six EUV coronal channels of the Solar Dynamics Observatory/Atmospheric Imaging Assembly. We performed both a differential emission measure (DEM) and a time-lag analysis, including a new method to isolate the relevant signal from the foreground and background emission. For the three events, the DEM undergoes long-period pulsations, which is a signature of periodic heating even though the loops are captured in their cooling phase, as is the bulk of the active regions. We link long-period intensity pulsations to new signatures of loop heating with strong evidence for evaporation and condensation cycles. We thus simultaneously witness widespread cooling and TNE. Finally, we discuss the implications of our new observations for both static and impulsive heating models. Title: Instant: An Innovative L5 Small Mission Concept for Coordinated Science with Solar Orbiter and Solar Probe Plus Authors: Lavraud, B.; Liu, Y. D.; Harrison, R. A.; Liu, W.; Auchere, F.; Gan, W.; Lamy, P. L.; Xia, L.; Eastwood, J. P.; Wimmer-Schweingruber, R. F.; Zong, Q.; Rochus, P.; Maksimovic, M.; Temmer, M.; Escoubet, C. P.; Kilpua, E.; Rouillard, A. P.; Davies, J. A.; Vial, J. C.; Gopalswamy, N.; Bale, S. D.; Li, G.; Howard, T. A.; DeForest, C. E. Bibcode: 2014AGUFMSH21B4109L Altcode: We will present both the science objectives and related instrumentation of a small solar and heliospheric mission concept, INSTANT: INvestigation of Solar-Terrestrial Activity aNd Transients. It will be submitted as an opportunity to the upcoming ESA-China S-class mission call later this year. This concept was conceived to allow innovative measurements and unprecedented, early determination of key properties of Earthbound CMEs from the L5 vantage point. Innovative measurements will include magnetic field determination in the corona thanks to Hanle measurement in Lyman-α and polarized heliospheric imaging for accurate determination of CME trajectories. With complementary in situ measurements, it will uniquely permit solar storm science, solar storm surveillance, and synergy with Solar Orbiter and Solar Probe Plus (the ESA-China S2 mission launch is planned in 2021). Title: Waves and Magnetism in the Solar Atmosphere (WAMIS) Authors: Ko, Y. K.; Auchere, F.; Casini, R.; Fineschi, S.; Gibson, S. E.; Knoelker, M.; Korendyke, C.; Laming, J. M.; Mcintosh, S. W.; Moses, J. D.; Romoli, M.; Rybak, J.; Socker, D. G.; Strachan, L.; Tomczyk, S.; Vourlidas, A.; Wu, Q. Bibcode: 2014AGUFMSH53B4221K Altcode: Magnetic fields in the solar atmosphere provide the energy for most varieties of solar activity, including high-energy electromagnetic radiation, solar energetic particles, flares, and coronal mass ejections, as well as powering the solar wind. Despite the fundamental role of magnetic fields in solar and heliospheric physics, there exists only very limited measurements of the field above the base of the corona. What is needed are direct measurements of not only the strength and orientation of the magnetic field but also the signatures of wave motions in order to better understand coronal structure, solar activity and the role of MHD waves in heating and accelerating the solar wind. Fortunately, the remote sensing instrumentation used to make magnetic field measurements is also well suited for measuring the Doppler signature of waves in the solar structures. With this in mind, we are proposing the WAMIS (Waves and Magnetism in the Solar Atmosphere) investigation. WAMIS will take advantage of greatly improved infrared (IR) detectors, forward models, advanced diagnostic tools and inversion codes to obtain a breakthrough in the measurement of coronal magnetic fields and in the understanding of the interaction of these fields with space plasmas. This will be achieved with a high altitude balloon borne payload consisting of a coronagraph with an IR spectro-polarimeter focal plane assembly. The balloon platform provides minimum atmospheric absorption and scattering at the IR wavelengths in which these observations are made. Additionally, a NASA long duration balloon flight mission from the Antarctic can achieve continuous observations over most of a solar rotation, covering all of the key time scales for the evolution of coronal magnetic fields. With these improvements in key technologies along with experience gained from current ground-based instrumentation, WAMIS will provide a low-cost mission with a high technology readiness leve. Title: Precision VUV Spectro-Polarimetry for Solar Chromospheric Magnetic Field Measurements Authors: Ishikawa, R.; Bando, T.; Hara, H.; Ishikawa, S.; Kano, R.; Kubo, M.; Katsukawa, Y.; Kobiki, T.; Narukage, N.; Suematsu, Y.; Tsuneta, S.; Aoki, K.; Miyagawa, K.; Ichimoto, K.; Kobayashi, K.; Auchère, F.; Clasp Team Bibcode: 2014ASPC..489..319I Altcode: The Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP) is a VUV spectro-polarimeter optimized for measuring the linear polarization of the Lyman-α line (121.6 nm) to be launched in 2015 with NASA's sounding rocket (Ishikawa et al. 2011; Narukage et al. 2011; Kano et al. 2012; Kobayashi et al. 2012). With this experiment, we aim to (1) observe the scattering polarization in the Lyman-α line, (2) detect the Hanle effect, and (3) assess the magnetic fields in the upper chromosphere and transition region for the first time. The polarization measurement error consists of scale error δ a (error in amplitude of linear polarization), azimuth error Δφ (error in the direction of linear polarization), and spurious polarization ɛ (false linear polarization signals). The error ɛ should be suppressed below 0.1% in the Lyman-α core (121.567 nm ±0.02 nm), and 0.5% in the Lyman-α wing (121.567 nm ±0.05 nm), based on our scientific requirements shown in Table 2 of Kubo et al. (2014). From scientific justification, we adopt Δ φ<2° and δ a<10% as the instrument requirements. The spectro-polarimeter features a continuously rotating MgF2 waveplate (Ishikawa et al. 2013), a dual-beam spectrograph with a spherical grating working also as a beam splitter, and two polarization analyzers (Bridou et al. 2011), which are mounted at 90 degree from each other to measure two orthogonal polarization simultaneously. For the optical layout of the CLASP instrument, see Figure 3 in Kubo et al. (2014). Considering the continuous rotation of the half-waveplate, the modulation efficiency is 0.64 both for Stokes Q and U. All the raw data are returned and demodulation (successive addition or subtraction of images) is done on the ground.

We control the CLASP polarization performance in the following three steps. First, we evaluate the throughput and polarization properties of each optical component in the Lyman-α line, using the Ultraviolet Synchrotron ORbital Radiation Facility (UVSOR) at the Institute for Molecular Science. The second step is polarization calibration of the spectro-polarimeter after alignment. Since the spurious polarization caused by the axisymmetric telescope is estimated to be negligibly small because of the symmetry (Ishikawa et al. 2014), we do not perform end-to-end polarization calibration. As the final step, before the scientific observation near the limb, we make a short observation at the Sun center and verify the polarization sensitivity, because the scattering polarization is expected to be close to zero at the Sun center due to symmetric geometry. In order to clarify whether we will be able to achieve the required polarization sensitivity and accuracy via these steps, we exercise polarization error budget, by investigating all the possible causes and their magnitudes of polarization errors, all of which are not necessarily verified by the polarization calibration. Based on these error budgets, we conclude that a polarization sensitivity of 0.1% in the line core, δ a<10% and Δ φ<2° can be achieved combined with the polarization calibration of the spectro-polarimeter and the onboard calibration at the Sun center(refer to Ishikawa et al. 2014, for the detail).

We are currently conducting verification tests of the flight components and development of the UV light source for the polarization calibration. From 2014 spring, we will begin the integration, alignment, and calibration. We will update the error budgets throughout the course of these tests. Title: A Sounding Rocket Experiment for the Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP) Authors: Kubo, M.; Kano, R.; Kobayashi, K.; Bando, T.; Narukage, N.; Ishikawa, R.; Tsuneta, S.; Katsukawa, Y.; Ishikawa, S.; Suematsu, Y.; Hara, H.; Shimizu, T.; Sakao, T.; Ichimoto, K.; Goto, M.; Holloway, T.; Winebarger, A.; Cirtain, J.; De Pontieu, B.; Casini, R.; Auchère, F.; Trujillo Bueno, J.; Manso Sainz, R.; Belluzzi, L.; Asensio Ramos, A.; Štěpán, J.; Carlsson, M. Bibcode: 2014ASPC..489..307K Altcode: A sounding-rocket experiment called the Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP) is presently under development to measure the linear polarization profiles in the hydrogen Lyman-alpha (Lyα) line at 121.567 nm. CLASP is a vacuum-UV (VUV) spectropolarimeter to aim for first detection of the linear polarizations caused by scattering processes and the Hanle effect in the Lyα line with high accuracy (0.1%). This is a fist step for exploration of magnetic fields in the upper chromosphere and transition region of the Sun. Accurate measurements of the linear polarization signals caused by scattering processes and the Hanle effect in strong UV lines like Lyα are essential to explore with future solar telescopes the strength and structures of the magnetic field in the upper chromosphere and transition region of the Sun. The CLASP proposal has been accepted by NASA in 2012, and the flight is planned in 2015. Title: Current progress of optical alignment procedure of CLASP's Lyman-alpha polarimetry instrument Authors: Giono, G.; Ishikawa, R.; Katsukawa, Y.; Bando, T.; Kano, R.; Suematsu, Y.; Narukage, N.; Sakao, Taro; Kobayashi, K.; Auchère, F. Bibcode: 2014SPIE.9144E..3EG Altcode: The Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP) is a sounding-rocket instrument currently under development at the National Astronomical Observatory of Japan (NAOJ) as a part of an international collaboration. CLASP's optics are composed of a Cassegrain telescope and a spectro-polarimeter which are designed to achieve an unprecedentedly accurate polarization measurement of the Ly-α line at 121.6nm emitted from the solar upper-chromosphere and transition region. CLASP's first flight is scheduled for August 2015. Reaching such accuracy requires a careful alignment of the optical elements to optimize the image quality at 121.6 nm. However Ly-α is absorbed by air and therefore the optics alignment has to be done under vacuum condition which makes any experiment difficult. To bypass this issue, we proposed to align the telescope and the spectrograph separately in visible light. Hence we present our alignment procedure for both telescope and spectro-polarimeter. We will explain details about the telescope preliminary alignment before mirrors coating, which was done in April 2014, present the telescope combined optical performance and compare them to CLASP tolerance. Then we will present details about an experiment designed to confirm our alignment procedure for the CLASP spectro-polarimeter. We will discuss the resulting image quality achieved during this experiment and the lessons learned. Title: The extreme UV imager of solar orbiter: from detailed design to flight model Authors: Halain, J. -P.; Rochus, P.; Renotte, E.; Auchère, F.; Berghmans, D.; Harra, L.; Schühle, U.; Schmutz, W.; Zhukov, A.; Aznar Cuadrado, R.; Delmotte, F.; Dumesnil, C.; Gyo, M.; Kennedy, T.; Mercier, R.; Verbeeck, F.; Thome, M.; Heerlein, K.; Hermans, A.; Jacques, L.; Mazzoli, A.; Meining, S.; Rossi, L.; Tandy, J.; Smith, P.; Winter, B. Bibcode: 2014SPIE.9144E..08H Altcode: The Extreme Ultraviolet Imager (EUI) on-board the Solar Orbiter mission will provide full-sun and high-resolution image sequences of the solar atmosphere at selected spectral emission lines in the extreme and vacuum ultraviolet. After the breadboarding and prototyping activities that focused on key technologies, the EUI project has completed the design phase and has started the final manufacturing of the instrument and its validation. The EUI instrument has successfully passed its Critical Design Review (CDR). The process validated the detailed design of the Optical Bench unit and of its sub-units (entrance baffles, doors, mirrors, camera, and filter wheel mechanisms), and of the Electronic Box unit. In the same timeframe, the Structural and Thermal Model (STM) test campaign of the two units have been achieved, and allowed to correlate the associated mathematical models. The lessons learned from STM and the detailed design served as input to release the manufacturing of the Qualification Model (QM) and of the Flight Model (FM). The QM will serve to qualify the instrument units and sub-units, in advance of the FM acceptance tests and final on-ground calibration. Title: Long-period intensity pulsations in the solar corona during activity cycle 23 Authors: Auchère, F.; Bocchialini, K.; Solomon, J.; Tison, E. Bibcode: 2014A&A...563A...8A Altcode: 2013arXiv1312.3792A We report on the detection (10σ) of 917 events of long-period (3 to 16 h) intensity pulsations in the 19.5 nm passband of the SOHO Extreme ultraviolet Imaging Telescope. The data set spans from January 1997 to July 2010, i.e. the entire solar cycle 23 and the beginning of cycle 24. The events can last for up to six days and have relative amplitudes up to 100%. About half of the events (54%) are found to happen in active regions, and 50% of these have been visually associated with coronal loops. The remaining 46% are localized in the quiet Sun. We performed a comprehensive analysis of the possible instrumental artefacts and we conclude that the observed signal is of solar origin. We discuss several scenarios that could explain the main characteristics of the active region events. The long periods and the amplitudes observed rule out any explanation in terms of magnetohydrodynamic waves. Thermal non-equilibrium could produce the right periods, but it fails to explain all the observed properties of coronal loops and the spatial coherence of the events. We propose that moderate temporal variations of the heating term in the energy equation, so as to avoid a thermal non-equilibrium state, could be sufficient to explain those long-period intensity pulsations. The large number of detections suggests that these pulsations are common in active regions. This would imply that the measurement of their properties could provide new constraints on the heating mechanisms of coronal loops.

Movies are available in electronic form at http://www.aanda.org Title: INSTANT: INvestigation of Solar-Terrestrial Associated Natural Threats Authors: Lavraud, Benoit; Vial, Jean-Claude; Harrison, Richard; Davies, Jackie; Escoubet, C. Philippe; Zong, Qiugang; Auchere, Frederic; Liu, Ying; Bale, Stuart; Gopalswamy, Nat; Li, Gang; Maksimovic, Milan; Liu, William; Rouillard, Alexis Bibcode: 2014cosp...40E1758L Altcode: The INSTANT mission will tackle both compelling solar and heliospheric science objectives and novel space weather capabilities. This is allowed by combining innovative and state-of-the-art instrumentation at an appropriate off-Sun-Earth line location on an orbit lagging the Earth around the Sun, near the L5 Lagrangian point. It is an affordable mission that tackles major objectives of the European and Chinese communities in terms of space physics and space weather. The science objectives are: 1. What is the magnetic field magnitude and topology in the corona? 2. How does the magnetic field reconfigure itself during CME eruptions? 3. What are the sources and links between the slow and fast winds? 4. How do CMEs accelerate and interact in the interplanetary medium? The mission will further allow the following crucial space weather capabilities: 5. Three-days advance knowledge of CIR properties that reach Earth. 6. Twelve hours to 2 days advance warning of Earth-directed CMEs. 7. Thanks to Lyman-α observations, first-ever capability of determining the magnetic field magnitude and orientation of Earth-directed CMEs. The mission will be proposed in the context of the upcoming ESA-China S-class call for mission. Title: Chromospheric Lyman-alpha spectro-polarimeter (CLASP) Authors: Kano, Ryouhei; Katsukawa, Yukio; Kubo, Masahito; Auchere, Frederic; Ishikawa, Ryohko; Kobayashi, Ken; Narukage, Noriyuki; Trujillo Bueno, Javier; Bando, Takamasa; Ishikawa, Shin-nosuke Bibcode: 2014cosp...40E1383K Altcode: In the solar chromosphere, magneto-hydrodynamic waves and super-sonic jets ubiquitously happen as revealed by the Japanese solar satellite Hinode. Now, we understand that the solar chromosphere is not a simple intermediate layer smoothly connecting the photosphere and corona, but a site where those dynamics may play an important role in the chromospheric and coronal heating. Such discoveries imply that the next frontier in solar physics lies in simultaneous observations between the dynamics and magnetic structures in the chromosphere and transition region, where the gas-dominant photosphere changes to the magnetic-dominant corona. Therefore, we promote the Chromospheric Lyman-Alpha SpectroPolarimeter (CLASP), which is a NASA's sounding rocket experiment scheduled in 2015 for aiming to infer the magnetic field information in the solar chromosphere and transition region. CLASP makes precise measurement (0.1%) of the polarization profile of the Lyman-alpha line, and aims to make the first ever measurement of the Hanle effect polarization caused by magnetic fields in the upper solar atmosphere. It is also a pathfinder to establish a new measurement tool for chromospheric and transition-region magnetic fields, and to make progress on chromospheric studies in future missions. Title: MASC: Magnetic Activity of the Solar Corona Authors: Auchere, Frederic; Fineschi, Silvano; Gan, Weiqun; Peter, Hardi; Vial, Jean-Claude; Zhukov, Andrei; Parenti, Susanna; Li, Hui; Romoli, Marco Bibcode: 2014cosp...40E.149A Altcode: We present MASC, an innovative payload designed to explore the magnetic activity of the solar corona. It is composed of three complementary instruments: a Hard-X-ray spectrometer, a UV / EUV imager, and a Visible Light / UV polarimetric coronagraph able to measure the coronal magnetic field. The solar corona is structured in magnetically closed and open structures from which slow and fast solar winds are respectively released. In spite of much progress brought by two decades of almost uninterrupted observations from several space missions, the sources and acceleration mechanisms of both types are still not understood. This continuous expansion of the solar atmosphere is disturbed by sporadic but frequent and violent events. Coronal mass ejections (CMEs) are large-scale massive eruptions of magnetic structures out of the corona, while solar flares trace the sudden heating of coronal plasma and the acceleration of electrons and ions to high, sometimes relativistic, energies. Both phenomena are most probably driven by instabilities of the magnetic field in the corona. The relations between flares and CMEs are still not understood in terms of initiation and energy partition between large-scale motions, small-scale heating and particle acceleration. The initiation is probably related to magnetic reconnection which itself results magnetic topological changes due to e.g. flux emergence, footpoints motions, etc. Acceleration and heating are also strongly coupled since the atmospheric heating is thought to result from the impact of accelerated particles. The measurement of both physical processes and their outputs is consequently of major importance. However, despite its fundamental importance as a driver for the physics of the Sun and of the heliosphere, the magnetic field of our star’s outer atmosphere remains poorly understood. This is due in large part to the fact that the magnetic field is a very difficult quantity to measure. Our knowledge of its strength and orientation is primarily based on extrapolations from photospheric observations, not from direct measurements. These extrapolations require strong assumptions on critical but unobserved quantities and thus fail to accurately reproduce the complex topologies inferred from remote-sensing observations of coronal structures in white light, EUV, and X-rays. Direct measurements of the coronal magnetic field are also clearly identified by the international heliophysics community as a key element susceptible to lead to major breakthroughs in the understanding of our star. MASC is thus designed to answer the following top-level scientific questions: 1. What is the global magnetic field configuration in the corona? 2. What is the role of the magnetic field in the triggering of flares and CMEs? 3. What is the role of the magnetic field in the acceleration mechanisms of the solar winds? 4. What is the energy spectrum and in particular what are the highest energies to which charged particles can be accelerated in the solar corona? MASC will address these fundamental questions with a suite of instruments composed of an X-ray spectrometer, a UV / EUV imager, and a coronagraph working in the visible and at Lyman alpha. The spectrometer will provide information on the energetics of solar flares, in particular at very high energies of accelerated particles. The UV / EUV imager will provide constraints on the temperature of the flaring and non-flaring corona. The coronagraph will provide the number density of free electrons in the corona, maps of the outflow velocity of neutral hydrogen, and measurements of the coronal magnetic field, via the Hanle effect. These measurements will be performed at all steps of the flare-CME processes, thus providing a detailed picture of the solar coronal dynamics in the quiet and eruptive periods. Title: The Solar EUV flux in the 3D Heliosphere Authors: Auchere, Frederic; Von Steiger, Rudolf; McMullin, Donald; Newmark, Jeffrey Bibcode: 2014cosp...40E.150A Altcode: The absolute measurement of solar EUV flux and its time dependence provide critical data on the solar driven photo chemistry which results in solar system objects. For example, the Solar HeII 30.4 nm emission is a major contributor to photo-ionization in the heliosphere, and thus 30.4 nm measurements provide the data required to determine the absolute photoionization rate of neutral interstellar helium flowing into our solar system. However, because of the orbit characteristics of the vast majority of spacecraft, the solar irradiance has mostly been measured at Earth or at least in the plane of the ecliptic. Therefore, the existing data ignore the fact that the angular distribution of the solar flux is largely anisotropic. Indeed, in the far and extreme ultraviolet, the chromosphere and the corona display very contrasted structures. At solar minimum, the polar regions are darkened by large coronal holes, and in the most active part of the solar cycle, bright active regions are scattered around the solar globe at low heliocentric latitudes. To date, due to the small number of off- ecliptic measurements, very few attempts have been made to investigate these variations. The implications of the anisotropy of the solar irradiance are diverse. For example, in the case of the 121.6 nm line of H I, the latitudinal anisotropy must be taken into account when modeling the Lyman alpha resonantly backscattered sky background. Identically, the anisotropy must be included in the modeling of the intensity of the HI 121.6 nm and He II 30.4 nm resonantly scattered coronal lines. We present here a generalization of an earlier work on the anisotropy of the 30.4 nm EUV flux. Our empirical model, is now able to synthethize solar spectra as seen from any point in the heliosphere in the 10 to 50 nm wavelength range. The model is based on a Differential Emission Measure resonstruction of the spectrum from reprojected EUV Carrington maps of the Sun. We present the results obtained on the 3D distribution of the Solar EUV flux during solar cycle 23. We discuss their consequences on the GAS/Ulysses measurements of the Helium abundance in the Local Interstellar Medium. Title: Observations and possible interpretations of very long period intensity pulsations in solar coronal loops Authors: Froment, Clara; Solomon, Jacques; Buchlin, Eric; Bocchialini, Karine; Auchere, Frederic; Guennou, Chloe Bibcode: 2014cosp...40E.903F Altcode: We discovered that intensity pulsations with periods ranging from 3 to 16 hours are common in solar coronal loops. Initially developed for EIT/SOHO 195 nm images, the automatic detection algorithm is now running on AIA/SDO data and allows detection of pulsation events in six coronal bands simultaneously. From may 2010 to december 2013, we detected more than 2000 events in the 6 EUV bands. We focus our study on pulsations in active regions and in particular in solar coronal loops where most of events are detected. A multi-wavelength analysis of some characteristic events is presented to help understand their physical nature. We perform a Differential Emission Measure analysis on AIA time series in order to determine the temporal variations of the thermal structure of the pulsating loops. This analysis gives important clues to investigate possible physical interpretations in particular in term of small perturbations of loops in static equilibrium and to study how this can constraint coronal heating models. We will also compare our observations to the results of a MHD turbulence and heating model of coronal loops. Title: Future L5 Missions for Solar Physics and Space Weather Authors: Auchere, Frederic; Gopalswamy, Nat Bibcode: 2014cosp...40E.148A Altcode: Coronal mass ejections (CMEs) and corotating interaction regions (CIR) are the sources of intense space weather in the heliosphere. Most of the current knowledge on CMEs accumulated over the past few decades has been derived from observations made from the Sun-Earth line, which is not the ideal vantage point to observe Earth-affecting CMEs (Gopalswamy et al., 2011a,b). In this paper, the advantages of remote-sensing and in-situ observations from the Sun-Earth L5 point are discussed. Locating a mission at Sun-Earth L5 has several key benefits for solar physics and space weather: (1) off the Sun-Earth line view is critical in observing Earth-arriving parts of CMEs, (2) L5 coronagraphic observations can also provide near-Sun space speed of CMEs, which is an important input to models that forecast Earth-arrival time of CMEs, (3) backside and frontside CMEs can be readily distinguished even without inner coronal imagers, (4) preceding CMEs in the path of Earth-affecting CMEs can be identified for a better estimate of the travel time, (5) CIRs reach the L5 point a few days before they arrive at Earth, and hence provide significant lead time before CIR arrival, (6) L5 observations can provide advance knowledge of CME and CIR source regions (coronal holes) rotating to Earth view, and (7) magnetograms obtained from L5 can improve the surface magnetic field distribution used as input to MHD models that predict the background solar wind. The paper also discusses L5 mission concepts that can be achieved in the near future. References Gopalswamy, N., Davila, J. M., St. Cyr, O. C., Sittler, E. C., Auchère, F., Duvall, T. L., Hoeksema, J. T., Maksimovic, M., MacDowall, R. J., Szabo, A., Collier, M. R. (2011a), Earth-Affecting Solar Causes Observatory (EASCO): A potential International Living with a Star Mission from Sun-Earth L5 JASTP 73, 658-663, DOI: 10.1016/j.jastp.2011.01.013 Gopalswamy, N., Davila, J. M., Auchère, F., Schou, J., Korendyke, C. M. Shih, A., Johnston, J. C., MacDowall, R. J., Maksimovic, M., Sittler, E., et al. (2011b), Earth-Affecting Solar Causes Observatory (EASCO): a mission at the Sun-Earth L5, Solar Physics and Space Weather Instrumentation IV. Ed. Fineschi, S. & Fennelly, J., Proceedings of the SPIE, Volume 8148, article id. 81480Z, DOI: 10.1117/12.901538 Title: Innovative multilayer coated optics for Solar Physics Authors: Meltchakov, Evgueni; Auchere, Frederic; Delmotte, Franck; De Rossi, Sebastien; Mercier, Raymond; Zhang, Xueyan Bibcode: 2014cosp...40E2069M Altcode: Development of multilayer coated optics with specific spectral characteristics and enhanced temporal, thermal and radiation stability requires an innovative approach to the design of reflecting multilayers and optimization of the coating process. Here we report on the progress in design, calculations and fabrication of reflecting multilayer coatings for solar imaging in the extreme ultra-violet (EUV) range. We will present recent results of characterization of new tri-component periodic multilayer structures containing aluminum as a low absorbing material within the spectral range from 17 to 40 nm. The EUV peak reflectance of these coatings (for instance, the Al/Mo/SiC multilayers) reaches 56% at 17.4 nm and 42% at 30 nm, highest reported up to now for these wavelengths. We have studied the temporal and thermal stability of structural and optical parameters of Al-based multilayer coatings as well as the resistivity of the coatings to high-energy and high-dose proton irradiation. A special attention will be drawn to specific bi-periodic systems with enhanced selectivity, which possess two efficient reflection bands and attenuate some unwanted emission lines in the EUV range. Experimental results show that such multilayer coatings are good candidates for the EUV imaging telescopes of Solar Orbiter and future solar missions. Title: UV spectropolarimeter design for precise polarization measurement and its application to the CLASP for exploration of magnetic fields in solar atmosphere Authors: Narukage, Noriyuki; Katsukawa, Yukio; Hara, Hirohisa; Kubo, Masahito; Auchere, Frederic; Ishikawa, Ryohko; Kano, Ryouhei; Bando, Takamasa; Ishikawa, Shin-nosuke; Suematsu, Yoshinori; Tsuneta, Saku Bibcode: 2014cosp...40E2232N Altcode: In order to measure the magnetic field in the region where the hot plasma from 10 (4) K to 10 (6) K is occupied, e.g., for solar atmosphere, the polarimetric measurements in ultra violet (UV) with 0.1% accuracy are required. In this paper, we propose a new UV spectropolarimeter design with 0.1% sensitivity in polarization measurement. This spectropolarimeter has two devices for the 0.1% accuracy. First, all optical components except the waveplate are the reflective type ones that can be equipped with the high reflectivity coating for the high throughput. Secondly, it equips the optically symmetric dual channels to measure the orthogonal linear polarization state simultaneously, using a concave diffraction grating as both the spectral dispersion element and the beam splitter. These two devices make the spurious polarizations caused by the photon noise, by the intensity variation of the observation target, and, by the instrument itself, enough small to achieve the 0.1% accuracy in polarization measurement. The spectropolarimeter thus designed is currently under fabrication for the sounding rocket project of Chromospheric Lyman-Alpha SpectroPolarimeter (CLASP) that aims at the direct measurement of the magnetic fields in solar atmosphere with Lyman-alpha line (121.6 nm) for the first time. Title: On-Orbit Degradation of Solar Instruments Authors: BenMoussa, A.; Gissot, S.; Schühle, U.; Del Zanna, G.; Auchère, F.; Mekaoui, S.; Jones, A. R.; Walton, D.; Eyles, C. J.; Thuillier, G.; Seaton, D.; Dammasch, I. E.; Cessateur, G.; Meftah, M.; Andretta, V.; Berghmans, D.; Bewsher, D.; Bolsée, D.; Bradley, L.; Brown, D. S.; Chamberlin, P. C.; Dewitte, S.; Didkovsky, L. V.; Dominique, M.; Eparvier, F. G.; Foujols, T.; Gillotay, D.; Giordanengo, B.; Halain, J. P.; Hock, R. A.; Irbah, A.; Jeppesen, C.; Judge, D. L.; Kretzschmar, M.; McMullin, D. R.; Nicula, B.; Schmutz, W.; Ucker, G.; Wieman, S.; Woodraska, D.; Woods, T. N. Bibcode: 2013SoPh..288..389B Altcode: 2013arXiv1304.5488B We present the lessons learned about the degradation observed in several space solar missions, based on contributions at the Workshop about On-Orbit Degradation of Solar and Space Weather Instruments that took place at the Solar Terrestrial Centre of Excellence (Royal Observatory of Belgium) in Brussels on 3 May 2012. The aim of this workshop was to open discussions related to the degradation observed in Sun-observing instruments exposed to the effects of the space environment. This article summarizes the various lessons learned and offers recommendations to reduce or correct expected degradation with the goal of increasing the useful lifespan of future and ongoing space missions. Title: Can the Differential Emission Measure Constrain the Timescale of Energy Deposition in the Corona? Authors: Guennou, C.; Auchère, F.; Klimchuk, J. A.; Bocchialini, K.; Parenti, S. Bibcode: 2013ApJ...774...31G Altcode: 2013arXiv1306.3114G In this paper, the ability of the Hinode/EIS instrument to detect radiative signatures of coronal heating is investigated. Recent observational studies of active region cores suggest that both the low and high frequency heating mechanisms are consistent with observations. Distinguishing between these possibilities is important for identifying the physical mechanism(s) of the heating. The differential emission measure (DEM) tool is one diagnostic that allows us to make this distinction, through the amplitude of the DEM slope coolward of the coronal peak. It is therefore crucial to understand the uncertainties associated with these measurements. Using proper estimations of the uncertainties involved in the problem of DEM inversion, we derive confidence levels on the observed DEM slope. Results show that the uncertainty in the slope reconstruction strongly depends on the number of lines constraining the slope. Typical uncertainty is estimated to be about ±1.0 in the more favorable cases. Title: The SWAP EUV Imaging Telescope Part I: Instrument Overview and Pre-Flight Testing Authors: Seaton, D. B.; Berghmans, D.; Nicula, B.; Halain, J. -P.; De Groof, A.; Thibert, T.; Bloomfield, D. S.; Raftery, C. L.; Gallagher, P. T.; Auchère, F.; Defise, J. -M.; D'Huys, E.; Lecat, J. -H.; Mazy, E.; Rochus, P.; Rossi, L.; Schühle, U.; Slemzin, V.; Yalim, M. S.; Zender, J. Bibcode: 2013SoPh..286...43S Altcode: 2012SoPh..tmp..217S; 2012arXiv1208.4631S The Sun Watcher with Active Pixels and Image Processing (SWAP) is an EUV solar telescope onboard ESA's Project for Onboard Autonomy 2 (PROBA2) mission launched on 2 November 2009. SWAP has a spectral bandpass centered on 17.4 nm and provides images of the low solar corona over a 54×54 arcmin field-of-view with 3.2 arcsec pixels and an imaging cadence of about two minutes. SWAP is designed to monitor all space-weather-relevant events and features in the low solar corona. Given the limited resources of the PROBA2 microsatellite, the SWAP telescope is designed with various innovative technologies, including an off-axis optical design and a CMOS-APS detector. This article provides reference documentation for users of the SWAP image data. Title: Chromospheric Lyman Alpha SpectroPolarimeter: CLASP Authors: Kobayashi, Ken; Kano, R.; Trujillo Bueno, J.; Winebarger, A. R.; Cirtain, J. W.; Bando, T.; De Pontieu, B.; Ishikawa, R.; Katsukawa, Y.; Kubo, M.; Narukage, N.; Sakao, T.; Tsuneta, S.; Auchère, F.; Asensio Ramos, A.; Belluzzi, L.; Carlsson, M.; Casini, R.; Hara, H.; Ichimoto, K.; Manso Sainz, R.; Shimizu, T.; Stepan, J.; Suematsu, Y.; Holloway, T. Bibcode: 2013SPD....44..142K Altcode: The Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP) is a VUV spectropolarimeter optimized for measuring the linear polarization of the Lyman-alpha line (121.6 nm). The Lyman-alpha line is predicted to show linear polarization caused by atomic scattering in the chromosphere and modified by the magnetic field through the Hanle effect. The Hanle effect is sensitive to weaker magnetic fields than Zeeman effect, and is not canceled by opposing fields, making it sensitive to tangled or unresolved magnetic field structures. These factors make the Hanle effect a valuable tool for probing the magnetic field in the chromosphere above the quiet sun. To meet this goal, CLASP is designed to measure linear polarization with 0.1% polarization sensitivity at 0.01 nm spectral resolution and 10" spatial resolution. CLASP is scheduled to be launched in 2015. Title: The LYOT+ UV/EUV instrumentation for measuring the magnetic field in the corona Authors: Auchère, Frederic; Vial, Jean Claude Bibcode: 2013EGUGA..1513788A Altcode: The solar corona is the seat of a variability which involves basic processes of plasma-magnetic field interaction in the universe, while also being a source of disturbances for spacecraft, technology, and possibly for human beings. Of special interest are coronal mass ejections (CMEs) with their associated Eruptive Prominences (EPs). Since they are basically driven by instabilities of the magnetic field in the corona, the measurement of the magnetic field before, after (and during) the event is critical in the corona. Also of interest for these studies and the source of the solar wind, the radial velocity of the plasma is a critical parameter to be determined. We present a new proposal to CNES called LYOT+ which meets the above-mentioned objectives: measurement of the coronal magnetic field up to 2 solar radii, of the electron density and the radial velocity. These measurements are complemented by EUV images of the underlying corona providing plasma diagnostic and magnetic field morphology. We describe the proposed combination of EUV imager and VUV and visible coronagraph. A main feature of the proposed instrumentation is the extended overlap of the fields-of-view of both instruments. In our presentation, we focus on the polarimetric concept which leads to the determination of the magnetic field through the Hanle effect. We also mention the extensive studies already performed in designing the instrumentation and testing parts of it. In summary, science, instrumentation and constraints on missions on which LYOT+ could be implemented, are presented. Title: Tomographic reconstructions of large scale coronal structures Authors: Guennou, C.; Auchère, F.; Seaton, D.; Canou, A.; Barbey, N.; Bocchialini, K. Bibcode: 2013enss.confE..83G Altcode: Classical plasma diagnostic techniques suffer from the line of sight (LOS) integration problem, which can confuse structures to the point that measurements crucial to the understanding of coronal physics are difficult to interpret. Tomography provides one way of understanding the LOS content, giving important insights on the morphology and physical properties of the coronal structures. Large scale, long-lived, arch-like structures are observed in the field of view of EUV telescopes at mid-latitudes, most notably in the 174 nm passband. In the present work, we use tomographic inversions of the solar corona the 3D morphology of these structures. We focus on a 28 days period of data from July/August 2012 during which some of these features were observed up to 1.7 Rsol by the SWAP/PROBA2 telescope. Additional multi-wavelength observations in the 6 bands of AIA/SDO are used to derive the corresponding 3-D maps of electron density and temperature. The results are then compared with global magnetic field extrapolations. We conclude by proposing an interpretation of the morphology of these structures as seen in EUV images. Title: TomograPy: A Fast, Instrument-Independent, Solar Tomography Software Authors: Barbey, N.; Guennou, C.; Auchère, F. Bibcode: 2013SoPh..283..227B Altcode: 2011SoPh..tmp..181B; 2011SoPh..tmp..250B; 2011arXiv1103.5904B; 2011SoPh..tmp..126B Solar tomography has progressed rapidly in recent years thanks to the development of robust algorithms and the availability of more powerful computers. It can today provide crucial insights in solving issues related to the line-of-sight integration present in the data of solar imagers and coronagraphs. However, there remain challenges such as the increase of the available volume of data, the handling of the temporal evolution of the observed structures, and the heterogeneity of the data in multi-spacecraft studies. We present a generic software package that can perform fast tomographic inversions that scales linearly with the number of measurements, linearly with the length of the reconstruction cube (and not the number of voxels), and linearly with the number of cores and can use data from different sources and with a variety of physical models: TomograPy (http://nbarbey.github.com/TomograPy/), an open-source software freely available on the Python Package Index. For performance, TomograPy uses a parallelized-projection algorithm. It relies on the World Coordinate System standard to manage various data sources. A variety of inversion algorithms are provided to perform the tomographic-map estimation. A test suite is provided along with the code to ensure software quality. Since it makes use of the Siddon algorithm it is restricted to rectangular parallelepiped voxels but the spherical geometry of the corona can be handled through proper use of priors. We describe the main features of the code and show three practical examples of multi-spacecraft tomographic inversions using STEREO/EUVI and STEREO/COR1 data. Static and smoothly varying temporal evolution models are presented. Title: Coronal Temperature Maps from Solar EUV Images: A Blind Source Separation Approach Authors: Dudok de Wit, T.; Moussaoui, S.; Guennou, C.; Auchère, F.; Cessateur, G.; Kretzschmar, M.; Vieira, L. A.; Goryaev, F. F. Bibcode: 2013SoPh..283...31D Altcode: 2012SoPh..tmp..258D; 2012arXiv1203.0116D; 2012SoPh..tmp..276D Multi-wavelength solar images in the extreme ultraviolet (EUV) are routinely used for analysing solar features such as coronal holes, filaments, and flares. However, images taken in different bands often look remarkably similar, as each band receives contributions coming from regions with a range of different temperatures. This has motivated the search for empirical techniques that may unmix these contributions and concentrate salient morphological features of the corona in a smaller set of less redundant source images. Blind Source Separation (BSS) does precisely this. Here we show how this novel concept also provides new insight into the physics of the solar corona, using observations made by SDO/AIA. The source images are extracted using a Bayesian positive source-separation technique. We show how observations made in six spectral bands, corresponding to optically thin emissions, can be reconstructed by a linear combination of three sources. These sources have a narrower temperature response and allow for considerable data reduction, since the pertinent information from all six bands can be condensed into a single composite picture. In addition, they give access to empirical temperature maps of the corona. The limitations of the BSS technique and some applications are briefly discussed. Title: GAIA-DEM : The Gaussian AIA DEm Maps database Authors: Guennou, C.; Auchère, F.; Soubrié, E.; Bocchialini, K. Bibcode: 2013enss.confE...7G Altcode: Providing the amount of emitting material as a function of the temperature along the line-of-sight, the Differential Emisssion Measure (DEM) analysis is a widespread diagnostic tool, used for most types of coronal structures. With six available coronal bands, the AIA instrument on board the SDO satellite provides new possibilities to more reliably estimate the DEM than previous UV imagers, and over a large FOV. The purpose of this database is to provide synoptic Gaussian DEM inversions of the AIA data. Using our recent results (Guennou et al. 2012a and 2012b), these maps can be then interpreted, taking advantage of our new tools developed to facilitate the DEM interpretation. The GAIA database provides the best Gaussian DEM fit matching the observations. A Gaussian form is a good first order approximation to determine the main thermal characteristics of the coronal plasma. With generally four inversions per day, at a 6 hours cadence, this database enables the user to quickly examine the global evolution of the thermal structure of the solar corona. DEM maps are available at http://medoc-dem.ias.u-psud.fr/. Title: FESTIVAL 5.0 - AIA and more ! Authors: Auchère, F.; Soubrié, E. Bibcode: 2013enss.confE.141A Altcode: FESTIVAL is an open source IDL-based browser designed for simultaneous and dynamic compositing of multi-instrument imaging data. FESTIVAL is very flexible and works with FITS files, which allows advanced processing. It is distributed as a Solar Software package. Initially developed for SECCHI, FESTIVAL now supports most space imaging telescopes, the latest additions being AIA /SDO and SWAP / Proba2. Its native zoom/pan mouse navigation mode makes it well suited to the large format of AIA images. In additio, version 5.0 brings a variety of new features making FESTIVAL even more powerful: enhanced search options, base and N-x running differences, solar rotation compensation, remote access to the MEDOC data archive, etc. Title: Can the Differential Emission Measure diagnostic be used to constrain the timescale of energy deposition in the corona? Authors: Guennou, C.; Auchère, F.; Klimchuk, J. A.; Bocchialini, K.; Parenti, S. Bibcode: 2013enss.confE..34G Altcode: Differential emission measure (DEM) analysis is a widespread tool used to diagnose the thermal properties of coronal plasmas. The slope of the DEM distribution coolward of the coronal peak (near 3-4MK in active regions) can be used to diagnose the timescale for the energy deposition repeating on a given magnetic strand. Recent AR studies suggest that some active region cores are consistent with low frequency heating mechanisms, where the plasma cools completely before being reheated, while other show consistency with high frequency energy deposition, where rapid reheating causes the temperature to fluctuate about a particular value. Distinguishing between these possibilities is important for identifying the physical mechanism of the heating. It is therefore crucial to understand the uncertainties in measurements of observed DEM slopes. In this work, based on a probabilistic approach and Monte Carlo simulations, we carefully assess the errors in the slopes determined from EIS data. We consider both the random errors due to photon counting statistics, and the systematic errors associated with uncertainties in atomic physics and instrument calibration. The technique developed provides all the solutions consistent with the data and their associated probabilities. We demonstrate how the quality and the accuracy of the inversion are affected by the presence of noises and systematic errors, and we characterise the quality of the DEM inversion and its statistical properties. From these results, estimation of the uncertainties in the reconstructed slopes can be derived, thereby allowing a proper interpretation of the degree of agreement between observations and heating model predictions. Title: MEDIA : MEDoc Interface for AIA Authors: Alingery, P.; Soubrié, E.; Auchère, F.; Bocchialini, K.; Boignard, J. P.; Buchlin, E.; Malappert, J. C.; Parenti, S. Bibcode: 2013enss.confE..88A Altcode: MEDOC, the space solar data center at Orsay (http://www.ias.u-psud.fr/medoc) is now providing a new web access to the AIA/SDO level 1 images. This interface has the advantage of being simple, intuitive, very stable and fast. The full resolution 4k x 4k AIA level 1 images archived at MEDOC are downloaded from upstream DRMS nodes with a 1 minute cadence at all wavelengths. The dataset will be kept online on a redundant archive for the whole SDO mission duration. The FITS files are accessible via an user friendly web interface (http://medoc-sdo.ias.u-psud.fr) that allows users to request data by selecting a date range, the desired wavelengths and a sampling rate (choosing a cadence from 1 minute to 1 day). For each file, users can preview the image (using the Helioviewer tool) or display the header information before downloading the FITS files (with or without Rice-compression). This web interface was built using Sitools2, a tool developed by CNES, the French space agency, and supports most browsers. For more advanced users, a Search/Get Python module is also available at http://sdo.ias.u-psud.fr/python. The users can use it to build more complex yet more powerful queries. We encourage everyone in Europe and beyond to use these new services! Title: On the Accuracy of the Differential Emission Measure Diagnostics of Solar Plasmas. Application to SDO/AIA. II. Multithermal Plasmas Authors: Guennou, C.; Auchère, F.; Soubrié, E.; Bocchialini, K.; Parenti, S.; Barbey, N. Bibcode: 2012ApJS..203...26G Altcode: 2012arXiv1210.2302G Differential emission measure (DEM) analysis is one of the most used diagnostic tools for solar and stellar coronae. Being an inverse problem, it has limitations due to the presence of random and systematic errors. We present in this series of papers an analysis of the robustness of the inversion in the case of SDO/AIA observations. We completely characterize the DEM inversion and its statistical properties, providing all the solutions consistent with the data along with their associated probabilities, and a test of the suitability of the assumed DEM model. While Paper I focused on isothermal conditions, we now consider multithermal plasmas and investigate both isothermal and multithermal solutions. We demonstrate how the ambiguity between noises and multithermality fundamentally limits the temperature resolution of the inversion. We show that if the observed plasma is multithermal, isothermal solutions tend to cluster on a constant temperature whatever the number of passbands or spectral lines. The multithermal solutions are also found to be biased toward near-isothermal solutions around 1 MK. This is true even if the residuals support the chosen DEM model, possibly leading to erroneous conclusions on the observed plasma. We propose tools for identifying and quantifying the possible degeneracy of solutions, thus helping the interpretation of DEM inversion. Title: On the Accuracy of the Differential Emission Measure Diagnostics of Solar Plasmas. Application to SDO/AIA. I. Isothermal Plasmas Authors: Guennou, C.; Auchère, F.; Soubrié, E.; Bocchialini, K.; Parenti, S.; Barbey, N. Bibcode: 2012ApJS..203...25G Altcode: 2012arXiv1210.2304G Differential emission measure (DEM) analysis is a major diagnostic tool for stellar atmospheres. However, both its derivation and its interpretation are notably difficult because of random and systematic errors, and the inverse nature of the problem. We use simulations with simple thermal distributions to investigate the inversion properties of SDO/AIA observations of the solar corona. This allows a systematic exploration of the parameter space, and using a statistical approach the respective probabilities of all the DEMs compatible with the uncertainties can be computed. Following this methodology, several important properties of the DEM inversion, including new limitations, can be derived and presented in a very synthetic fashion. In this first paper, we describe the formalism and we focus on isothermal plasmas as building blocks to understand the more complex DEMs studied in the second paper. The behavior of the inversion of AIA data being thus quantified, and we provide new tools to properly interpret the DEM. We quantify the improvement of the isothermal inversion with six AIA bands compared to previous EUV imagers. The maximum temperature resolution of AIA is found to be 0.03 log Te , and we derive a rigorous test to quantify the compatibility of observations with the isothermal hypothesis. However, we demonstrate limitations in the ability of AIA alone to distinguish different physical conditions. Title: Measurements and Modeling of Heliospheric EUV Spectral Irradiance and Luminosity Authors: Floyd, L. E.; McMullin, D. R.; Auchere, F. Bibcode: 2012AGUFMSH11B2212F Altcode: For more than 15 years, The EIT and the later EUVI instruments aboard SoHO and STEREO, respectively, have provided a time series of images of the solar radiance in the HeII 30.4 nm transition region and three coronal emission lines (FeIX/X, FeXII, and FeXV) of differing temperatures. While the EIT measurements were gathered from a position very near to the Earth-Sun axis, the EUVI measurements were gathered at angles ranging up to and in excess of ±90 degrees in solar longitude from the Earth-Sun axis. Using a Differential Emission Measure (DEM) model, these measurements provide the basis for estimates of the spectral irradiance for the entire solar spectrum up to about 50 nm at any position in the heliosphere. These spectra are utilized in this work for two purposes. First, the photoionization rate of neutral He at each position is calculated. Neutral He is of interest because it traverses the heliopause relatively undisturbed and therefore provides a measure of isotopic parameters beyond the heliosphere. Second, we use these generate a time series of estimates of the solar EUV spectral luminosity extending from the recent post Solar Cycle 23 minimum into the current unusually weak rise of Solar Cycle 24. Because this EUV spectral luminosity is the sum of all solar radiation at each wavelength in every direction, their time series should not contain any systematic 27-day solar rotation periodicities as do typical solar activity indices and its presence would be an indication of time series reliability. This EUV luminosity time series is compared with other solar indices such as SSN and the F10.7 radio flux. Title: LEMUR: Large European module for solar Ultraviolet Research. European contribution to JAXA's Solar-C mission Authors: Teriaca, Luca; Andretta, Vincenzo; Auchère, Frédéric; Brown, Charles M.; Buchlin, Eric; Cauzzi, Gianna; Culhane, J. Len; Curdt, Werner; Davila, Joseph M.; Del Zanna, Giulio; Doschek, George A.; Fineschi, Silvano; Fludra, Andrzej; Gallagher, Peter T.; Green, Lucie; Harra, Louise K.; Imada, Shinsuke; Innes, Davina; Kliem, Bernhard; Korendyke, Clarence; Mariska, John T.; Martínez-Pillet, Valentin; Parenti, Susanna; Patsourakos, Spiros; Peter, Hardi; Poletto, Luca; Rutten, Robert J.; Schühle, Udo; Siemer, Martin; Shimizu, Toshifumi; Socas-Navarro, Hector; Solanki, Sami K.; Spadaro, Daniele; Trujillo-Bueno, Javier; Tsuneta, Saku; Dominguez, Santiago Vargas; Vial, Jean-Claude; Walsh, Robert; Warren, Harry P.; Wiegelmann, Thomas; Winter, Berend; Young, Peter Bibcode: 2012ExA....34..273T Altcode: 2011ExA...tmp..135T; 2011arXiv1109.4301T The solar outer atmosphere is an extremely dynamic environment characterized by the continuous interplay between the plasma and the magnetic field that generates and permeates it. Such interactions play a fundamental role in hugely diverse astrophysical systems, but occur at scales that cannot be studied outside the solar system. Understanding this complex system requires concerted, simultaneous solar observations from the visible to the vacuum ultraviolet (VUV) and soft X-rays, at high spatial resolution (between 0.1'' and 0.3''), at high temporal resolution (on the order of 10 s, i.e., the time scale of chromospheric dynamics), with a wide temperature coverage (0.01 MK to 20 MK, from the chromosphere to the flaring corona), and the capability of measuring magnetic fields through spectropolarimetry at visible and near-infrared wavelengths. Simultaneous spectroscopic measurements sampling the entire temperature range are particularly important. These requirements are fulfilled by the Japanese Solar-C mission (Plan B), composed of a spacecraft in a geosynchronous orbit with a payload providing a significant improvement of imaging and spectropolarimetric capabilities in the UV, visible, and near-infrared with respect to what is available today and foreseen in the near future. The Large European Module for solar Ultraviolet Research (LEMUR), described in this paper, is a large VUV telescope feeding a scientific payload of high-resolution imaging spectrographs and cameras. LEMUR consists of two major components: a VUV solar telescope with a 30 cm diameter mirror and a focal length of 3.6 m, and a focal-plane package composed of VUV spectrometers covering six carefully chosen wavelength ranges between 170 Å and 1270 Å. The LEMUR slit covers 280'' on the Sun with 0.14'' per pixel sampling. In addition, LEMUR is capable of measuring mass flows velocities (line shifts) down to 2 km s - 1 or better. LEMUR has been proposed to ESA as the European contribution to the Solar C mission. Title: Chromospheric Lyman-alpha spectro-polarimeter (CLASP) Authors: Kano, Ryouhei; Bando, Takamasa; Narukage, Noriyuki; Ishikawa, Ryoko; Tsuneta, Saku; Katsukawa, Yukio; Kubo, Masahito; Ishikawa, Shin-nosuke; Hara, Hirohisa; Shimizu, Toshifumi; Suematsu, Yoshinori; Ichimoto, Kiyoshi; Sakao, Taro; Goto, Motoshi; Kato, Yoshiaki; Imada, Shinsuke; Kobayashi, Ken; Holloway, Todd; Winebarger, Amy; Cirtain, Jonathan; De Pontieu, Bart; Casini, Roberto; Trujillo Bueno, Javier; Štepán, Jiří; Manso Sainz, Rafael; Belluzzi, Luca; Asensio Ramos, Andres; Auchère, Frédéric; Carlsson, Mats Bibcode: 2012SPIE.8443E..4FK Altcode: One of the biggest challenges in heliophysics is to decipher the magnetic structure of the solar chromosphere. The importance of measuring the chromospheric magnetic field is due to both the key role the chromosphere plays in energizing and structuring the outer solar atmosphere and the inability of extrapolation of photospheric fields to adequately describe this key boundary region. Over the last few years, significant progress has been made in the spectral line formation of UV lines as well as the MHD modeling of the solar atmosphere. It is found that the Hanle effect in the Lyman-alpha line (121.567 nm) is a most promising diagnostic tool for weaker magnetic fields in the chromosphere and transition region. Based on this groundbreaking research, we propose the Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP) to NASA as a sounding rocket experiment, for making the first measurement of the linear polarization produced by scattering processes and the Hanle effect in the Lyman-alpha line (121.567 nm), and making the first exploration of the magnetic field in the upper chromosphere and transition region of the Sun. The CLASP instrument consists of a Cassegrain telescope, a rotating 1/2-wave plate, a dual-beam spectrograph assembly with a grating working as a beam splitter, and an identical pair of reflective polarization analyzers each equipped with a CCD camera. We propose to launch CLASP in December 2014. Title: Multi Element Telescope for Imaging and Spectroscopy (METIS) coronagraph for the Solar Orbiter mission Authors: Antonucci, Ester; Fineschi, Silvano; Naletto, Giampiero; Romoli, Marco; Spadaro, Daniele; Nicolini, Gianalfredo; Nicolosi, Piergiorgio; Abbo, Lucia; Andretta, Vincenzo; Bemporad, Alessandro; Auchère, Frédéric; Berlicki, Arkadiusz; Bruno, Roberto; Capobianco, Gerardo; Ciaravella, Angela; Crescenzio, Giuseppe; Da Deppo, Vania; D'Amicis, Raffaella; Focardi, Mauro; Frassetto, Fabio; Heinzel, Peter; Lamy, Philippe L.; Landini, Federico; Massone, Giuseppe; Malvezzi, Marco A.; Moses, J. Dan; Pancrazzi, Maurizio; Pelizzo, Maria-Guglielmina; Poletto, Luca; Schühle, Udo H.; Solanki, Sami K.; Telloni, Daniele; Teriaca, Luca; Uslenghi, Michela Bibcode: 2012SPIE.8443E..09A Altcode: METIS, the “Multi Element Telescope for Imaging and Spectroscopy”, is a coronagraph selected by the European Space Agency to be part of the payload of the Solar Orbiter mission to be launched in 2017. The unique profile of this mission will allow 1) a close approach to the Sun (up to 0.28 A.U.) thus leading to a significant improvement in spatial resolution; 2) quasi co-rotation with the Sun, resulting in observations that nearly freeze for several days the large-scale outer corona in the plane of the sky and 3) unprecedented out-of-ecliptic view of the solar corona. This paper describes the experiment concept and the observational tools required to achieve the science drivers of METIS. METIS will be capable of obtaining for the first time: • simultaneous imaging of the full corona in polarized visible-light (590-650 nm) and narrow-band ultraviolet HI Lyman α (121.6 nm); • monochromatic imaging of the full corona in the extreme ultraviolet He II Lyman α (30.4 nm); • spectrographic observations of the HI and He II Ly α in corona. These measurements will allow a complete characterization of the three most important plasma components of the corona and the solar wind, that is, electrons, hydrogen, and helium. This presentation gives an overview of the METIS imaging and spectroscopic observational capabilities to carry out such measurements. Title: The EUI instrument on board the Solar Orbiter mission: from breadboard and prototypes to instrument model validation Authors: Halain, J. -P.; Rochus, P.; Renotte, E.; Appourchaux, T.; Berghmans, D.; Harra, L.; Schühle, U.; Schmutz, W.; Auchère, F.; Zhukov, A.; Dumesnil, C.; Delmotte, F.; Kennedy, T.; Mercier, R.; Pfiffner, D.; Rossi, L.; Tandy, J.; BenMoussa, A.; Smith, P. Bibcode: 2012SPIE.8443E..07H Altcode: The Solar Orbiter mission will explore the connection between the Sun and its heliosphere, taking advantage of an orbit approaching the Sun at 0.28 AU. As part of this mission, the Extreme Ultraviolet Imager (EUI) will provide full-sun and high-resolution image sequences of the solar atmosphere at selected spectral emission lines in the extreme and vacuum ultraviolet. To achieve the required scientific performances under the challenging constraints of the Solar Orbiter mission it was required to further develop existing technologies. As part of this development, and of its maturation of technology readiness, a set of breadboard and prototypes of critical subsystems have thus been realized to improve the overall instrument design. The EUI instrument architecture, its major components and sub-systems are described with their driving constraints and the expected performances based on the breadboard and prototype results. The instrument verification and qualification plan will also be discussed. We present the thermal and mechanical model validation, the instrument test campaign with the structural-thermal model (STM), followed by the other instrument models in advance of the flight instrument manufacturing and AIT campaign. Title: On the Thermal diagnostics of Coronal Loops with SDO/AIA Authors: Guennou, Chloe; Parenti, Susanna; Bocchialini, Karine; Soubrie, Elie; Auchere, Frederic; Barbey, Nicolas Bibcode: 2012cosp...39..675G Altcode: 2012cosp.meet..675G With simultaneous observations in 6 coronal bands, AIA has the capability to provide spectral diagnostics over an extended field of view at high resolution and high cadence. Therefore, DEM diagnostics of coronal loops can in principle be performed routinely for statistical studies. We investigate here the pertinence of the DEM analysis with AIA. The inevitable presence of noises and uncertainties, incompleteness of the atomic physics databases lead to notable difficulties in the inversion process. The complications involved in the derivation of the DEM are one of the reasons of the controversial results regarding the thermal structure and thus the heating scenario of the coronal loops. The purpose of this work, based on a probabilistic approach, is precisely to investigate the properties of the solutions, providing a quantification of the DEM inversion problem robustness. The technique relies on Monte Carlo simulations of observed intensities in the six AIA coronal bands. The comparison between the known inputs and the inversion results allows us to determine the degree of robustness. This approach provides all the solutions consistent with the data along with their associated probabilities, as well as a test of the validity of the assumptions made on the DEM shape. Applications to SDO/AIA coronal loops data are presented. Title: Tomographic reconstruction of polar plumes Authors: Auchère, F.; Guennou, C.; Barbey, N. Bibcode: 2012EAS....55..207A Altcode: We present a tomographic reconstruction of polar plumes as observed in the Extreme Ultraviolet in January 2010. Plumes are elusive structures visible in polar coronal holes that may play an important role in the acceleration of the solar wind. However, despite numerous observations, little is irrefutably known about them. Because of line of sight effects, even their geometry is subject to debate. Are they genuine cylindrical features of the corona or are they only chance alignments along the line of sight? Tomography provides a means to reconstruct the volume of an optically thin object from a set of observations taken from different vantage points. In the case of the Sun, these are typically obtained by using a solar rotation worth of images, which limits the ability to reconstruct short lived structures. We present here a tomographic inversion of the solar corona obtained using only 6 days of data. This is achieved by using simultaneously three space telescopes (EUVI/STEREO and SWAP/PROBA2) in a very specific orbital configuration. The result is the shortest possible tomographic snapshot of polar plumes. The 3D reconstruction shows both quasi-cylindrical plumes and a network pattern that can mimic them by line of sight superimpositions. This suggests that the controversy on plume geometry is due to the coexistence of both types of structures. Title: Solar magnetism eXplorer (SolmeX). Exploring the magnetic field in the upper atmosphere of our closest star Authors: Peter, Hardi; Abbo, L.; Andretta, V.; Auchère, F.; Bemporad, A.; Berrilli, F.; Bommier, V.; Braukhane, A.; Casini, R.; Curdt, W.; Davila, J.; Dittus, H.; Fineschi, S.; Fludra, A.; Gandorfer, A.; Griffin, D.; Inhester, B.; Lagg, A.; Landi Degl'Innocenti, E.; Maiwald, V.; Sainz, R. Manso; Martínez Pillet, V; Matthews, S.; Moses, D.; Parenti, S.; Pietarila, A.; Quantius, D.; Raouafi, N. -E.; Raymond, J.; Rochus, P.; Romberg, O.; Schlotterer, M.; Schühle, U.; Solanki, S.; Spadaro, D.; Teriaca, L.; Tomczyk, S.; Trujillo Bueno, J.; Vial, J. -C. Bibcode: 2012ExA....33..271P Altcode: 2011arXiv1108.5304P; 2011ExA...tmp..134P The magnetic field plays a pivotal role in many fields of Astrophysics. This is especially true for the physics of the solar atmosphere. Measuring the magnetic field in the upper solar atmosphere is crucial to understand the nature of the underlying physical processes that drive the violent dynamics of the solar corona—that can also affect life on Earth. SolmeX, a fully equipped solar space observatory for remote-sensing observations, will provide the first comprehensive measurements of the strength and direction of the magnetic field in the upper solar atmosphere. The mission consists of two spacecraft, one carrying the instruments, and another one in formation flight at a distance of about 200 m carrying the occulter to provide an artificial total solar eclipse. This will ensure high-quality coronagraphic observations above the solar limb. SolmeX integrates two spectro-polarimetric coronagraphs for off-limb observations, one in the EUV and one in the IR, and three instruments for observations on the disk. The latter comprises one imaging polarimeter in the EUV for coronal studies, a spectro-polarimeter in the EUV to investigate the low corona, and an imaging spectro-polarimeter in the UV for chromospheric studies. SOHO and other existing missions have investigated the emission of the upper atmosphere in detail (not considering polarization), and as this will be the case also for missions planned for the near future. Therefore it is timely that SolmeX provides the final piece of the observational quest by measuring the magnetic field in the upper atmosphere through polarimetric observations. Title: Earth-Affecting Solar Causes Observatory (EASCO): a mission at the Sun-Earth L5 Authors: Gopalswamy, Nat; Davila, Joseph M.; Auchère, Frédéric; Schou, Jesper; Korendyke, Clarence M.; Shih, Albert; Johnston, Janet C.; MacDowall, Robert J.; Maksimovic, Milan; Sittler, Edward; Szabo, Adam; Wesenberg, Richard; Vennerstrom, Suzanne; Heber, Bernd Bibcode: 2011SPIE.8148E..0ZG Altcode: 2011SPIE.8148E..30G; 2011arXiv1109.2929G Coronal mass ejections (CMEs) and corotating interaction regions (CIRs) as well as their source regions are important because of their space weather consequences. The current understanding of CMEs primarily comes from the Solar and Heliospheric Observatory (SOHO) and the Solar Terrestrial Relations Observatory (STEREO) missions, but these missions lacked some key measurements: STEREO did not have a magnetograph; SOHO did not have in-situ magnetometer. SOHO and other imagers such as the Solar Mass Ejection Imager (SMEI) located on the Sun-Earth line are also not well-suited to measure Earth-directed CMEs. The Earth-Affecting Solar Causes Observatory (EASCO) is a proposed mission to be located at the Sun-Earth L5 that overcomes these deficiencies. The mission concept was recently studied at the Mission Design Laboratory (MDL), NASA Goddard Space Flight Center, to see how the mission can be implemented. The study found that the scientific payload (seven remote-sensing and three in-situ instruments) can be readily accommodated and can be launched using an intermediate size vehicle; a hybrid propulsion system consisting of a Xenon ion thruster and hydrazine has been found to be adequate to place the payload at L5. Following a 2-year transfer time, a 4-year operation is considered around the next solar maximum in 2025. Title: The coronal suprathermal particle explorer (C-SPEX) Authors: Moses, J. Daniel; Brown, Charles; Doschek, George; Ko, Yuan-Kuen; Korendyke, Clarence; Laming, J. Martin; Socker, Dennis; Tylka, Allen; McMullin, Donald; Ng, Chee; Wassom, Steven; Lee, Martin; Auchère, Frédéric; Fineschi, Silvano; Carter, Tim Bibcode: 2011SPIE.8148E..0JM Altcode: 2011SPIE.8148E..18M The primary science objective of the Coronal Suprathermal Particle Explorer (C-SPEX) is to investigate the spatial and temporal variations of coronal suprathermal particle populations that are seeds for acceleration to solar energetic particles (SEPs). It is understood that such seed particle populations vary with coronal structures and can change responding to solar flare and coronal mass ejection (CME) events. Models have shown that higher densities of suprathermal protons can result in higher rates of acceleration to high energies. Understanding the variations in the suprathermal seed particle population is thus crucial for understanding the variations in SEPs. However, direct measurements are still lacking. C-SPEX will measure the variation in the suprathermal protons across various coronal magnetic structures, before/after the passage of CME shocks, in the post-CME current sheets, and before/after major solar flares. Understanding the causes for variation in the suprathermal seed particle population and its effect on the variation in SEPs will also help build the predictive capability of SEPs that reach Earth. The CSPEX measurements will be obtained from instrumentation on the International Space Station (ISS) employing well-established UV coronal spectroscopy techniques. Title: Development of multilayer thin film filters for the full-sun imager on Solar Orbiter Authors: Auchère, Frédéric; Zhang, Xueyan; Delmotte, Franck; Meltchakov, Evgueni; BenMoussa, Ali Bibcode: 2011SPIE.8148E..0NA Altcode: 2011SPIE.8148E..21A Membranes a few hundred nanometers thick are used in EUV optics to make, for example, beams splitters or passband filters. Despite their necessity in numerous applications these components are, because of their thinness, extremely fragile and their implementation in space instruments is always difficult. The authors are developing thin film filters for the Full Sun Imager, one of the EUV telescopes on board the Solar Orbiter mission with objectives of high optical efficiency and mechanical strength. These filters are specifically designed to isolate one or the other of the two passbands (17.4 and 30.4 nm) reflected by the telescope's dual band mirror coating. In this paper we present the optical properties of the prototype components. Title: Morphology, dynamics and plasma parameters of plumes and inter-plume regions in solar coronal holes Authors: Wilhelm, K.; Abbo, L.; Auchère, F.; Barbey, N.; Feng, L.; Gabriel, A. H.; Giordano, S.; Imada, S.; Llebaria, A.; Matthaeus, W. H.; Poletto, G.; Raouafi, N. -E.; Suess, S. T.; Teriaca, L.; Wang, Y. -M. Bibcode: 2011A&ARv..19...35W Altcode: 2011arXiv1103.4481W Coronal plumes, which extend from solar coronal holes (CH) into the high corona and—possibly—into the solar wind (SW), can now continuously be studied with modern telescopes and spectrometers on spacecraft, in addition to investigations from the ground, in particular, during total eclipses. Despite the large amount of data available on these prominent features and related phenomena, many questions remained unanswered as to their generation and relative contributions to the high-speed streams emanating from CHs. An understanding of the processes of plume formation and evolution requires a better knowledge of the physical conditions at the base of CHs, in plumes and in the surrounding inter-plume regions. More specifically, information is needed on the magnetic field configuration, the electron densities and temperatures, effective ion temperatures, non-thermal motions, plume cross sections relative to the size of a CH, the plasma bulk speeds, as well as any plume signatures in the SW. In spring 2007, the authors proposed a study on `Structure and dynamics of coronal plumes and inter-plume regions in solar coronal holes' to the International Space Science Institute (ISSI) in Bern to clarify some of these aspects by considering relevant observations and the extensive literature. This review summarizes the results and conclusions of the study. Stereoscopic observations allowed us to include three-dimensional reconstructions of plumes. Multi-instrument investigations carried out during several campaigns led to progress in some areas, such as plasma densities, temperatures, plume structure and the relation to other solar phenomena, but not all questions could be answered concerning the details of plume generation process(es) and interaction with the SW. Title: AIA Observations of Sunspot Waves Authors: Leibacher, John W.; Soubrié, E.; Auchère, F.; Baudin, F. Bibcode: 2011SPD....42.2115L Altcode: 2011BAAS..43S.2115L Waves in the low solar atmosphere above sunspots i) present an interesting phenomenon in their own right, ii) are potentially a probe of magnetic structures (e.g. "plumes") in the sunspot atmosphere and a source of excitation of higher, coronal loop waves, and iii) are coupled to umbral flashes and sub-surface, helioseismic waves in a manner that is not fully understood. We present an analysis of AIA observations of waves in AR 11092, showing their propagation, temporal coherence, and angular symmetry; characterizing them in terms of frequency, amplitude, and propagation speed. Title: The Coronal Suprathermal Particle Explorer (C-SPEX) Authors: Moses, John Daniel; Brown, C. M.; Doschek, G. A.; -. Ko, Y.; Korendyke, C. M.; Laming, J. M.; Rakowski, C. E.; Socker, D. G.; Tylka, A.; Ng, C. K.; Wassom, S. R.; McMullin, D. R.; Lee, M. A.; Auchere, F.; Fineschi, S. Bibcode: 2011SPD....42.1519M Altcode: 2011BAAS..43S.1519M The primary science objective of the Coronal Suprathermal Particle Explorer (C-SPEX) is to investigate the spatial and temporal variations of coronal suprathermal particle populations that are seeds for acceleration to solar energetic particles (SEPs). It is understood that such seed particle populations vary with coronal structures and can change responding to solar flare and coronal mass ejection (CME) events. Models have shown that higher densities of suprathermal protons can result in higher rates of acceleration to high energies. Understanding the variations in the suprathermal seed particle population is thus crucial for understanding the variations in SEPs. However, direct measurements are still lacking.

C-SPEX will measure the variation in the suprathermal protons across various coronal magnetic structures, before/after the passage of CME shocks, in the post-CME current sheets, and before/after major solar flares. The measurements will not only constrain models of SEP acceleration but also constrain models of the production of suprathermal particles from processes such as magnetic reconnection at the Sun. Understanding the causes for variation in the suprathermal seed particle population and its effect on the variation in SEPs will also help build the predictive capability of SEPs that reach Earth.

The C-SPEX measurements will be obtained from instrumentation on the International Space Station (ISS) employing well-established UV coronal spectroscopy techniques. The unique aspect of C-SPEX is a >100-fold increase of light gathering power over any previous UV coronal spectrometer. It is demonstrated C-SPEX will thus overcome the limitations in signal to noise that have thwarted prior attempts to observe suprathermals in the corona.

The present lack of a means to predict the variability of SEP intensities and the likelihood C-SPEX will help develop such predictions makes the proposed investigation directly relevant to each of the three strategic objectives of the NASA Heliophysics Research Strategic Objectives. Title: TomograPy: A Fast, Instrument-Independent, Solar Tomography Software Authors: Barbey, Nicolas; Guennou, Chloé; Auchère, Frédéric Bibcode: 2011ascl.soft04001B Altcode: TomograPy is an open-source software freely available on the Python Package Index that can perform fast tomographic inversions that scale linearly with the number of measurements, linearly with the length of the reconstruction cube (and not the number of voxels) and linearly with the number of cores and can use data from different sources and with a variety of physical models. For performance, TomograPy uses a parallelized-projection algorithm. It relies on the World Coordinate System standard to manage various data sources. A variety of inversion algorithms are provided to perform the tomographic-map estimation. A test suite is provided along with the code to ensure software quality. Since it makes use of the Siddon algorithm it is restricted to rectangular parallelepiped voxels but the spherical geometry of the corona can be handled through proper use of priors. Title: Earth-Affecting Solar Causes Observatory (EASCO): A potential International Living with a Star Mission from Sun-Earth L5 Authors: Gopalswamy, N.; Davila, J. M.; St. Cyr, O. C.; Sittler, E. C.; Auchère, F.; Duvall, T. L.; Hoeksema, J. T.; Maksimovic, M.; MacDowall, R. J.; Szabo, A.; Collier, M. R. Bibcode: 2011JASTP..73..658G Altcode: This paper describes the scientific rationale for an L5 mission and a partial list of key scientific instruments the mission should carry. The L5 vantage point provides an unprecedented view of the solar disturbances and their solar sources that can greatly advance the science behind space weather. A coronagraph and a heliospheric imager at L5 will be able to view CMEs broadsided, so space speed of the Earth-directed CMEs can be measured accurately and their radial structure discerned. In addition, an inner coronal imager and a magnetograph from L5 can give advance information on active regions and coronal holes that will soon rotate on to the solar disk. Radio remote sensing at low frequencies can provide information on shock-driving CMEs, the most dangerous of all CMEs. Coordinated helioseismic measurements from the Sun-Earth line and L5 provide information on the physical conditions at the base of the convection zone, where solar magnetism originates. Finally, in situ measurements at L5 can provide information on the large-scale solar wind structures (corotating interaction regions (CIRs)) heading towards Earth that potentially result in adverse space weather. Title: Initiation and Early Development of the 2008 April 26 Coronal Mass Ejection Authors: Huang, J.; Démoulin, P.; Pick, M.; Auchère, F.; Yan, Y. H.; Bouteille, A. Bibcode: 2011ApJ...729..107H Altcode: We present a detailed study of a coronal mass ejection (CME) with high temporal cadence observations in radio and extreme-ultraviolet (EUV). The radio observations combine imaging of the low corona with radio spectra in the outer corona and interplanetary space. The EUV observations combine the three points of view of the STEREO and SOHO spacecraft. The beginning of the CME initiation phase is characterized by emissions that are signatures of the reconnection of the outer part of the erupting configuration with surrounding magnetic fields. Later on, a main source of emission is located in the core of the active region. It is an indirect signature of the magnetic reconnection occurring behind the erupting flux rope. Energetic particles are also injected in the flux rope and the corresponding radio sources are detected. Other radio sources, located in front of the EUV bright front, trace the interaction of the flux rope with the surrounding fields. Hence, the observed radio sources enable us to detect the main physical steps of the CME launch. We find that imaging radio emissions in the metric range permits us to trace the extent and orientation of the flux rope which is later detected in interplanetary space. Moreover, combining the radio images at various frequencies with fast EUV imaging permits us to characterize in space and time the processes involved in the CME launch. Title: Minimization of the shadow patterns produced by periodic mesh grids in extreme ultraviolet telescopes Authors: Auchère, Frédéric; Rizzi, Julien; Philippon, Anne; Rochus, Pierre Bibcode: 2011JOSAA..28...40A Altcode: Thin metallic films are used as passband filters in space telescopes operating in the extreme ultraviolet (EUV). Because of their thinness, typically 100 to 200nm, they are very sensitive to static pressure differentials and to mechanic and acoustic vibrations. Therefore, they are difficult to manage in all phases of a space program, from manufacturing to vacuum testing to launch. A common solution to this problem is to reinforce them with fine mesh grids with pitches ranging from a few hundred micrometers to a few millimeters. Depending on their location in the optical path, the main effect of these periodic grids is either to diffract light or to cast penumbral shadows on the focal plane. In this paper, we analyze the formation of the shadow modulation patterns and derive design rules to minimize their amplitude. The minimization principle is illustrated by an application to a solar EUV telescope. Title: Center-to-Limb Variation in the Solar HeII 30.4 nm Emission Line from STEREO EUVI Authors: Floyd, L. E.; McMullin, D. R.; Auchere, F. Bibcode: 2010AGUFMSH31C1803F Altcode: The variation of radiant energy that emerges from the each portion of the solar surface depends on the temperature and density structure of the solar atmosphere in those emitting regions. For wavelengths where the opacity is sufficiently large, some of the emissions are blocked by overlying plasma. HeII 30.4 nm (optically thick) solar emissions fall into this category. Accordingly, the center-to-limb (C2L) brightness variation across the solar disk will differ from that of optically thin emissions. Knowledge of the C2L variation provides important constraints on solar radiative transfer models in the lower transition region where these emissions are formed. Images from the EUVI instruments aboard the two STEREO spacecraft for the first time provide direct measurements of the C2L variation, especially in the channel centered on the strong HeII 30.4 nm emission. In general, comparisons of simultaneous images taken from different viewing angles in the ecliptic plane where the same regions of the Sun are measured provide the basis for C2L estimates. After 4 years of the STEREO mission, the increasing satellite separation provides the baseline dataset for sampling at nearly all angles. Simultaneous images are corrected for instrumental responsivity degradation and converted to purely HeII 30.4 nm radiation using a DEM model (ref needed). The C2L is expressed as parameterized models whose specific values are determined via iteration with the initial estimate based on pre-DEM images. Solar surface region types are segregated into different parameter sets by the implied intensity at disk center. Validation of the responsivity model is provided by measurements along the meridian halfway between the two satellites and through intercomparisons with simultaneous images from similar EIT instrument aboard SOHO. Validation of the model and approach are provided through similar calculations obtained for optically thin coronal lines such as FeXV. Title: The technical challenges of the Solar-Orbiter EUI instrument Authors: Halain, Jean-Philippe; Rochus, Pierre; Appourchaux, Thierry; Berghmans, David; Harra, Louise; Schühle, Udo; Auchère, Frédéric; Zhukov, Andrei; Renotte, Etienne; Defise, Jean-Marc; Rossi, Laurence; Fleury-Frenette, Karl; Jacques, Lionel; Hochedez, Jean-François; Ben Moussa, Ali Bibcode: 2010SPIE.7732E..0RH Altcode: 2010SPIE.7732E..20H The Extreme Ultraviolet Imager (EUI) onboard Solar Orbiter consists of a suite of two high-resolution imagers (HRI) and one dual-band full Sun imager (FSI) that will provide EUV and Lyman-α images of the solar atmospheric layers above the photosphere. The EUI instrument is based on a set of challenging new technologies allowing to reach the scientific objectives and to cope with the hard space environment of the Solar Orbiter mission. The mechanical concept of the EUI instrument is based on a common structure supporting the HRI and FSI channels, and a separated electronic box. A heat rejection baffle system is used to reduce the Sun heat load and provide a first protection level against the solar disk straylight. The spectral bands are selected by thin filters and multilayer mirror coatings. The detectors are 10μm pitch back illuminated CMOS Active Pixel Sensors (APS), best suited for the EUI science requirements and radiation hardness. This paper presents the EUI instrument concept and its major sub-systems. The current developments of the instrument technologies are also summarized. Title: Definition of an imaging spectrometer meeting the needs of UV solar physics Authors: Ruiz de Galarreta Fanjul, C.; Philippon, A.; Vial, J. -C.; Lemaire, P.; Maillard, J. -P.; Buisset, C.; Appourchaux, T.; Auchère, F. Bibcode: 2010SPIE.7732E..36R Altcode: 2010SPIE.7732E..99R The study of the outer solar atmosphere requires combining imaging and spectroscopy in the UV lines formed in the high chromosphere, the transition region and the corona. We start from the science requirements and we define the instrumental specifications in terms of field-of-view (FOV), spatial, temporal and spectral resolution and bandpass. We propose two different all-reflection optical architectures based on interferometric techniques: Spatial Heterodyne Spectroscopy (SHS); and Imaging Transform Spectrometer (IFTS). We describe the different set-ups and compare the potential performances of the two types of solutions, and discuss their feasibility. We conclude that IFTS appears to be the best solution, meeting the needs of UV solar physics. However, we point out the many difficulties to be encountered, especially as far as metrology is concerned. Title: HERSCHEL Sounding Rocket Mission Observations of the Helium Corona Authors: Newmark, Jeffrey; Moses, J.; Antonucci, E.; Fineschi, S.; Abbo, L.; Telloni, D.; Auchere, F.; Barbey, N.; Romoli, M. Bibcode: 2010AAS...21640721N Altcode: The HERSCHEL (Helium Resonant Scattering in the Corona and Heliosphere) investigation successfully obtained unprecedented images of the helium and hydrogen components of the solar corona out to 3 solar radii during a suborbital flight on 14 September 2009. Preliminary analysis of these observations indicates the spatial distribution of the helium abundance and outflow velocity provides powerful diagnostics for the source and dynamics of the slow solar wind during the time of solar minimum activity. An analysis of co-temporal STEREO EUVI data to derive the temperature of low coronal structures associated with the regions of enhanced helium abundance observed by HERSCHEL provides evidence the relative first ionization potential (FIP) of helium and hydrogen may play an important role in the observed abundance distribution.

NRL was supported by the Office of Naval Research and NASA under NDPRS6598G. Title: Hanle signatures of the coronal magnetic field in the linear polarization of the hydrogen Lα line Authors: Derouich, M.; Auchère, F.; Vial, J. C.; Zhang, M. Bibcode: 2010A&A...511A...7D Altcode: 2009arXiv0912.5068D
Aims: This paper is dedicated to the assessment of the validity of future coronal spectro-polarimetric observations and to prepare their interpretation in terms of the magnetic field vector.
Methods: We assume that the polarization of the hydrogen coronal Lα line is due to anisotropic scattering of an incident chromospheric radiation field. The anisotropy is due to geometrical effects but also to the inhomogeneities of the chromospheric regions which we model by using Carrington maps of the Lα. Because the corona is optically thin, we fully consider the effects of the integration over the line-of-sight (LOS). As a modeling case, we include a dipolar magnetic topology perturbed by a non-dipolar magnetic structure arising from a prominence current sheet in the corona. The spatial variation of the hydrogen density and the temperature is taken into account. We determine the incident radiation field developed on the tensorial basis at each point along the LOS. Then, we calculate the local emissivity vector to obtain integrated Stokes parameters with and without coronal magnetic field.
Results: We show that the Hanle effect is an interesting technique for interpreting the scattering polarization of the Lαλ1216 line in order to diagnose the coronal magnetic field. The difference between the calculated polarization and the zero magnetic field polarization gives us an estimation of the needed polarimetric sensitivity in future polarization observations. We also obtain useful indications about the optimal observational strategy.
Conclusions: Quantitative interpretation of the Hanle effect on the scattering linear polarization of Lα line can be a crucial source of information about the coronal magnetic field at a height over the limb h < 0.7 R. Therefore, one needs the development of spatial instrumentation to observe this line.

Present address: Colorado Research Associates Division, NorthWest Research Associates, Inc., 3380 Mitchell Ln., Boulder, CO 80301, USA. Title: The SDO data centre at IDOC/MEDOC in France Authors: Parenti, Susanna; Bocchialini, Karine; Soubrie, Elie; Auchere, Frederic; Ballans, Herv; Buchlin, Eric; Gabriel, Alan; Mercier, Claude; Poulleau, Gilles; Vial, Jean-Claude Bibcode: 2010cosp...38.2888P Altcode: 2010cosp.meet.2888P The IDOC/MEDOC centre at the Institut d'Astrophysique Spatiale (IAS, Université Paris 11/CNRS) has a long experience in solar data archiving and distribution, including almost 15 years of data from SOHO, STEREO and TRACE. The center is now expanding its activity and becoming a Pˆle Thématique Solaire of the CNES and INSU/CNRS. Part of the new activities of the centre will be linked to the arrival of the enormous volume of the new SDO data. The center will be one of the three European centers to receive and redistribute the data to the community. It will also be the only European site to permanently store about 10% of the data (mainly from AIA). In continuity with its previous activities, SDO data will be included in the data visualization tool FESTIVAL and it will provide new services, like tools for the solar feature identification (filaments, EUV intensity fluctuations). We will present an overview of the facilities and activities of the centre in relation to the SDO data. Title: On the observations and possible interpretations of very long period intensity oscillations of solar coronal loops Authors: Solomon, Jacques; Auchere, Frederic; Bocchialini, Karine; Gabriel, Alan; Tison, Emmanuelle Bibcode: 2010cosp...38.2853S Altcode: 2010cosp.meet.2853S A comprehensive analysis of intensity oscillations in the Fe XII line (19.5 nm) observed with EIT/SoHO in solar coronal loops during solar cycle 23 (january 1997-september 2008) was performed. About 450 occurences of oscillations were obtained with periods ranging between 3.4 and 13.6 hours and with durations up to about a hundred hours. Interpratations in term of slow waves or of thermal nonequilibrium were examined. However numerous inconsistencies arise between current theories (in fact mostly expressed in terms of various numerical simulations) and observations. Presently the lack of a direct link between those very long oscillation periods and the characteristic physical parameters of the loops (density, temperature, loop geometry) hampers making progress in this major issue. This situation requires an effort in a specific time analysis of the classical system of equations of the problem: the question is examined from different angles in relation to the data. Title: Large-scale Extreme-Ultraviolet Disturbances Associated with a Limb Coronal Mass Ejection Authors: Dai, Y.; Auchère, F.; Vial, J. -C.; Tang, Y. H.; Zong, W. G. Bibcode: 2010ApJ...708..913D Altcode: We present composite observations of a coronal mass ejection (CME) and the associated large-scale extreme-ultraviolet (EUV) disturbances on 2007 December 31 by the Extreme-ultraviolet Imager (EUVI) and COR1 coronagraph on board the recent Solar Terrestrial Relations Observatory mission. For this limb event, the EUV disturbances exhibit some typical characteristics of EUV Imaging Telescope waves: (1) in the 195 Å bandpass, diffuse brightenings are observed propagating oppositely away from the flare site with a velocity of ~260 km s-1, leaving dimmings behind; (2) when the brightenings encounter the boundary of a polar coronal hole, they stop there to form a stationary front. Multi-temperature analysis of the propagating EUV disturbances favors a heating process over a density enhancement in the disturbance region. Furthermore, the EUVI-COR1 composite display shows unambiguously that the propagation of the diffuse brightenings coincides with a large lateral expansion of the CME, which consequently results in a double-loop-structured CME leading edge. Based on these observational facts, we suggest that the wave-like EUV disturbances are a result of magnetic reconfiguration related to the CME liftoff rather than true waves in the corona. Reconnections between the expanding CME magnetic field lines and surrounding quiet-Sun magnetic loops account for the propagating diffuse brightenings; dimmings appear behind them as a consequence of volume expansion. X-ray and radio data provide us with complementary evidence. Title: Modeling and forecasting the 3D solar EUV flux Authors: Auchere, Frederic; McMullin, Donald Bibcode: 2010cosp...38.1097A Altcode: 2010cosp.meet.1097A The UV/EUV solar flux drives many physical processes in the heliosphere. One of its most important effects are the complex photochemistry reactions produced in the Planet's atmospheres. It is thus a key parameter in space weather, and there is today a clear need for reliable modeling and forecasting of the UV/EUV flux. The STEREO mission offers un unprecedented opportunity to improve and validate irradiance models and the associated pre-dictions. Indeed, the separation angle of the two probes allow or a better coverage of the solar surface, and the B probe monitors the upcoming hemisphere of the Sun a few days before it is visible from Earth. The authors have developped an empirical model of the three-dimensional EUV solar flux based on EIT/SOHO data. Taking into account the flux anisotropies, it can be used to compute and predict the irradiance at any position in the heliosphere. We present in this paper the generalization of this model to EUVI/STEREO data, and present the improved forecasting performances compared to those of the previous version. Title: Automatic detection and statistical analysis of intensity oscillations in the solar corona with SDO Authors: Auchere, Frederic; Bocchialini, Karine; Solomon, Jacques; Gabriel, Alan; Tison, Emmanuelle Bibcode: 2010cosp...38.2863A Altcode: 2010cosp.meet.2863A We present the generalization to SDO data of our automatic oscillation detection algorithm. This technique was successfully tested using EIT data on board SOHO at 19.5 nm from January 1997 to September 2008, i.e almost the entire solar cycle 23. In the EIT data set we detected 400 oscillations whose periods range between 3.4 and 13.6 h with a maximum around 6-7 hours. Most of the oscillations are localized in coronal structures associated with active regions and last several tens of hours. The AIA data will allow the detection of similar events in several coronal temperature bands simultaneously, which will help understand their physical nature. Title: Polarimetry of the Lα Line for Coronal Magnetic Field Diagnostic Authors: Derouich, M.; Auchère, F.; Vial, J. C.; Millard, A. A. Bibcode: 2009ASPC..405..389D Altcode: Measurement and physical interpretation of the scattering polarization of the Extreme-ultraviolet (EUV) and Far-UV (FUV) spectral lines provide a largely unexplored diagnostic of coronal magnetic field. In this context, we present the LYOT (LYman Orbiting Telescope) project that makes it possible to observe the Lα λ1216 line polarization in the solar corona. Because the corona is optically thin, it is necessary to consider the effects of the integration over the line-of-sight (LOS). The LOS effects have been usually addressed for non polarimetric studies where the unknown is a scalar quantity (the intensity) but not a Stokes vector. Previous studies investigating the coronal polarization are generally concerned with a local position of the scattering center and a deterministic magnetic field (see Raouafi et al.~2002 for a measurement and interpretation of the O VI λ 1032 line polarization). Here, we perform computations that test whether a LOS integrated Hanle effect can be detected in order to access to the magnetic field topology. Title: Coronal and Interplanetary Structures Associated with Type III Bursts Authors: Pick, M.; Kerdraon, A.; Auchère, F.; Stenborg, G.; Bouteille, A.; Soubrié, E. Bibcode: 2009SoPh..256..101P Altcode: This paper pursues former studies of the coronal structures that are associated with radio type III bursts by taking advantage of the new capabilities of STEREO/SECCHI. The data analysis has been performed for 02 and 03 June 2007. During these two days several type III bursts, which were detected in the corona and in the interplanetary medium, occurred during the observing time of the Nançay radioheliograph. Electron beams accelerated in the same active region and producing type III emissions almost at the same time, can propagate in different well defined coronal structures below 15 R. Then, these structures become imbedded in the same plasma sheet which can be tracked up to 0.25 AU. Inhomogeneities travel along these structures; their velocities measured between 15 and 35 R are typical of those of a slow solar wind. Comparison with PFSS magnetic field extrapolation shows that its connection with the IP magnetic field is different from what is suggested by the present observations. Title: Design and performance of two-channel EUV multilayer mirrors with enhanced spectral selectivity Authors: Hecquet, Christophe; Delmotte, Franck; Ravet-Krill, Marie-Françoise; de Rossi, Sébastien; Jérome, Arnaud; Bridou, Françoise; Varnière, Françoise; Meltchakov, Evgueni; Auchère, Frédéric; Giglia, Angelo; Mahne, Nicola; Nanaronne, Stefano Bibcode: 2009ApPhA..95..401H Altcode: 2009ApPhA.tmp...37H In this paper, we present a study on two-channel multilayer mirrors which can operate at two wavelengths in Extreme Ultraviolet (EUV) spectral range. We propose a new method to design two-channel EUV multilayer mirrors with enhanced spectral selectivity. The mirror structure is a stack of two periodic multilayers separated by a buffer layer. We have defined the main parameters which allow adjustment of the distance between different order Bragg’s peak and of wavelength positions of reflectivity minima. Two mirrors have been designed and deposited for solar EUV telescope applications by using this method. The first mirror reflects Fe IX-X line (17.1 nm) and Fe XVI (33.5 nm) lines with attenuation of the He II line (30.4 nm). The second mirror reflects Fe IX-X and He II lines with attenuation of Fe XV (28.4 nm) and Fe XVI lines. Measurements with synchrotron radiation source confirm that, in both cases, for these mirrors, we are able to adjust reflectivity maxima (Bragg peak position) and minima. Such multilayers offer new possibilities for compact design of multi-wavelength EUV telescopes and/or for high spectral selectivity. Title: Stellar and galactic environment survey (SAGE) Authors: Barstow, M. A.; Burleigh, M. R.; Bannister, N. J.; Lapington, J. S.; Kowalski, M. P.; Cruddace, R. G.; Wood, K. S.; Auchere, F.; Bode, M. F.; Bromage, G. E.; Gibson, B.; Collier Cameron, A.; Cassatella, A.; Delmotte, F.; Ravet, M. -F.; Doyle, J. G.; Jeffery, C. S.; Gaensicke, B.; Jordan, C.; Kappelmann, N.; Werner, K.; Lallement, R.; de Martino, D.; Matthews, S. A.; Phillips, K. J. H.; Del Zanna, G.; Orio, M.; Pace, E.; Pagano, I.; Schmitt, J. H. M. M.; Welsh, B. Y. Bibcode: 2009Ap&SS.320..231B Altcode: 2008Ap&SS.tmp..161B This paper describes a proposed high resolution soft X-ray and Extreme Ultraviolet (EUV) spectroscopy mission to carry out a survey of Stellar and Galactic Environments (SAGE). The payload is based on novel diffraction grating technology which has already been proven in a sub-orbital space mission and which is ready to fly on a satellite platform with minimal development. Much of the technical detail of the instrumentation has been reported elsewhere and we concentrate our discussion here on the scientific goals of a SAGE base-line mission, demonstrating the scientific importance of high resolution spectroscopy in the Extreme Ultraviolet for the study of stars and the local interstellar medium. Title: Solar EUV/FUV irradiance variations: analysis and observational strategy Authors: Kretzschmar, Matthieu; Dudok de Wit, Thierry; Lilensten, Jean; Hochedez, Jean-Francois; Aboudarham, Jean; Amblard, Pierre-Olivier; Auchère, Frederic; Moussaoui, Said Bibcode: 2009AcGeo..57...42K Altcode: 2008AcGeo..57...42K; 2008AcGeo.tmp...50K The knowledge of solar extreme and far ultraviolet (EUV) irradiance variations is essential for the characterization of the Earth’s upper atmosphere. For a long time, this knowledge has been based on empirical models, which are themselves based on proxies of the solar activity. However, the accurate modeling and prediction of the Earth’s upper atmosphere necessitate to improve the precision on the irradiance and its variations below about 200 nm. Here, we present a review of recent works made by the authors that aim at quantifying the irradiance variability at these wavelengths, and that lead to new way of monitoring the solar EUV/FUV irradiance spectrum. In more details, it is shown that the quantification of the high level of redundancy in the solar spectrum variability allows to envisage measuring only a small portion of the spectrum without losing essential knowledge. Finally, we discuss what should and could be measured in order to retrieve the solar extreme and far ultraviolet spectrum. Title: POLAR investigation of the Sun—POLARIS Authors: Appourchaux, T.; Liewer, P.; Watt, M.; Alexander, D.; Andretta, V.; Auchère, F.; D'Arrigo, P.; Ayon, J.; Corbard, T.; Fineschi, S.; Finsterle, W.; Floyd, L.; Garbe, G.; Gizon, L.; Hassler, D.; Harra, L.; Kosovichev, A.; Leibacher, J.; Leipold, M.; Murphy, N.; Maksimovic, M.; Martinez-Pillet, V.; Matthews, B. S. A.; Mewaldt, R.; Moses, D.; Newmark, J.; Régnier, S.; Schmutz, W.; Socker, D.; Spadaro, D.; Stuttard, M.; Trosseille, C.; Ulrich, R.; Velli, M.; Vourlidas, A.; Wimmer-Schweingruber, C. R.; Zurbuchen, T. Bibcode: 2009ExA....23.1079A Altcode: 2008ExA...tmp...40A; 2008arXiv0805.4389A The POLAR Investigation of the Sun (POLARIS) mission uses a combination of a gravity assist and solar sail propulsion to place a spacecraft in a 0.48 AU circular orbit around the Sun with an inclination of 75° with respect to solar equator. This challenging orbit is made possible by the challenging development of solar sail propulsion. This first extended view of the high-latitude regions of the Sun will enable crucial observations not possible from the ecliptic viewpoint or from Solar Orbiter. While Solar Orbiter would give the first glimpse of the high latitude magnetic field and flows to probe the solar dynamo, it does not have sufficient viewing of the polar regions to achieve POLARIS’s primary objective: determining the relation between the magnetism and dynamics of the Sun’s polar regions and the solar cycle. Title: Stellar And Galactic Environment survey (SAGE) Authors: Barstow, M. A.; Kowalski, M. P.; Cruddace, R. G.; Wood, K. S.; Auchere, F.; Bannister, N. J.; Bode, M. F.; Bromage, G. E.; Burleigh, M. R.; Collier Cameron, A.; Cassatella, A.; Delmotte, F.; Doyle, J. G.; Gaensicke, B.; Gibson, B.; Jeffery, C. S.; Jordan, C.; Kappelmann, N.; Lallement, R.; Lapington, J. S.; de Martino, D.; Matthews, S. A.; Orio, M.; Pace, E.; Pagano, I.; Phillips, K. J. H.; Ravet, M. -F.; Schmitt, J. H. M. M.; Welsh, B. Y.; Werner, K.; Del Zanna, G. Bibcode: 2009ExA....23..169B Altcode: 2008ExA...tmp...25B This paper describes a proposed high resolution soft X-ray and Extreme Ultraviolet spectroscopy mission to carry out a survey of Stellar and Galactic Environments (SAGE). The payload is based on novel diffraction grating technology which has already been proven in a sub-orbital space mission and which is ready to fly on a satellite platform with minimal development. We discuss the goals of a SAGE base-line mission and demonstrate the scientific importance of high resolution spectroscopy in the Extreme Ultraviolet for the study of stars and the local interstellar medium. Title: Solar EUV Spectral Irradiance Throughout The 3-Dimensional Heliosphere Authors: McMullin, D. R.; Auchere, F.; Cook, J. W.; Newmark, J. S.; Quemerais, E.; von Steiger, R.; Witte, M. Bibcode: 2008AGUFMSH13B1522M Altcode: When Ulysses moved from 30 to 80 degrees in solar latitude (July 2001), the Ulysses GAS instrument measured an apparent increase in the neutral He density. This is more naturally interpreted as a latitudinal dependence (decrease) of the loss rate due to solar photoionization rather than a true increase of the neutral He density. This concept has been tested through the development of a 3-Dimensional solar EUV model for the Heliosphere. The model concept has been presented earlier, and we are now presenting results and applications of the new model. Using daily SOHO EIT observations, over successive Carrington rotations, we have developed a three- dimensional model for solar EUV fluxes observed at any heliospheric position, projected to any heliospheric position. The combined effects of solar rotational and latitude-dependent flux variability are explicitly treated in this model. The flux model will be compared with other direct spectral irradiance observations in the ecliptic plane, such as those available from the TIMED SEE instrument as well as broadband measurements available from the SOHO/SEM irradiance time series. These comparisons will be used in part to validate the current results. We then use this flux to compute the photoionization rate of the in-flowing neutral Helium, and compare the modeled change with that observed along the spacecraft trajectory with the direct measurements from the out-of-ecliptic Ulysses GAS observations. The unique GAS comparisons will provide validation of the original hypothesis as to the latitudinal dependence (decrease) of the loss rate due to solar photoionization rather than an increase of the neutral He density. Title: Which solar EUV indices are best for reconstructing the solar EUV irradiance? Authors: Dudok de Wit, T.; Kretzschmar, M.; Aboudarham, J.; Amblard, P. -O.; Auchère, F.; Lilensten, J. Bibcode: 2008AdSpR..42..903D Altcode: 2007astro.ph..2053D The solar EUV irradiance is of key importance for space weather. Most of the time, however, surrogate quantities such as EUV indices have to be used by lack of continuous and spectrally resolved measurements of the irradiance. The ability of such proxies to reproduce the irradiance from different solar atmospheric layers is usually investigated by comparing patterns of temporal correlations. We consider instead a statistical approach. The TIMED/SEE experiment, which has been continuously operating since February 2002, allows for the first time to compare in a statistical manner the EUV spectral irradiance to five EUV proxies: the sunspot number, the f10.7, Ca K, and Mg II indices, and the He I equivalent width. Using multivariate statistical methods, we represent in a single graph the measure of relatedness between these indices and various strong spectral lines. The ability of each index to reproduce the EUV irradiance is discussed; it is shown why so few lines can be effectively reconstructed from them. All indices exhibit comparable performance, apart from the sunspot number, which is the least appropriate. No single index can satisfactorily describe both the level of variability on time scales beyond 27 days, and relative changes of irradiance on shorter time scales. Title: The EUV Sun as the superposition of elementary Suns Authors: Amblard, P. -O.; Moussaoui, S.; Dudok de Wit, T.; Aboudarham, J.; Kretzschmar, M.; Lilensten, J.; Auchère, F. Bibcode: 2008A&A...487L..13A Altcode: 2008arXiv0809.0566A Aims: Many studies assume that the solar irradiance in the EUV can be decomposed into different contributions, which makes modelling the spectral variability considerably easier. We consider a different approach in which these contributions are not imposed a priori but effectively and robustly inferred from spectral irradiance measurements.
Methods: This is a source separation problem with a positivity constraint, for which we use a Bayesian solution.
Results: Using five years of daily EUV spectra recorded by the TIMED/SEE satellite, we show that the spectral irradiance can be decomposed into three elementary spectra. Our results suggest that they describe different layers of the solar atmosphere rather than specific regions. The temporal variability of these spectra is discussed. Title: Two channel multilayer mirrors for astrophysics Authors: Gautier, Julien; Delmotte, Franck; Françoise Ravet, Marie; Jérome, Arnaud; Bridou, Françoise; Varnière, Francoise; Auchère, Frédéric Bibcode: 2008OptCo.281.3032G Altcode: A two-channel mirror reflecting both Fe-IX/X (λ = 17.1 nm) and He-II (30.4 nm) resonance lines at near normal incidence has been designed, fabricated and characterized. These two passbands are often chosen in space instruments designed for the observation of the solar corona. The mirror structure used for optimization is a superposition of two periodic multilayers with three components per period. It has been designed by using optimization software with an appropriate merit function. The theoretical reflectivity for both resonance lines can reach 0.25. It is shown that, by using a set of filters, one can select either the Fe-IX/X or the He-II channel. The spectral response of the two-channel mirror has been measured on synchrotron radiation source on a large wavelength range, from 12 nm to 35 nm. Experimental reflectivity reaches 0.32 for the Fe-IX/X line and 0.19 for the He-II line. Title: FESTIVAL: A Multiscale Visualization Tool for Solar Imaging Data Authors: Auchère, F.; Soubrié, E.; Bocchialini, K.; LeGall, F. Bibcode: 2008SoPh..248..213A Altcode: 2008SoPh..tmp...59A Since 4 December 2006, the SECCHI instrument suites onboard the two STEREO A and B probes have been imaging the solar corona and the heliosphere on a wide range of angular scales. The EUVI telescopes have a plate scale of 1.7 arcseconds pixel−1, while that of the HI2 wide-angle cameras is 2.15 arcminutes pixel−1, i.e. 75 times larger, with the COR1 and COR2 coronagraphs having intermediate plate scales. These very different instruments, aimed at studying Coronal Mass Ejections and their propagation in the heliosphere, create a data visualization challenge. This paper presents FESTIVAL, a SolarSoftware package originally developed to be able to map the SECCHI data into dynamic composite images of the sky as seen by the STEREO and SOHO probes. Data from other imaging instruments can also be displayed. Using the mouse, the user can quickly and easily zoom in and out and pan through these composite images to explore all spatial scales from EUVI to HI2 while keeping the native resolution of the original data. A large variety of numerical filters can be applied, and additional data (i.e. coordinate grids, stars catalogs, etc.) can be overlaid on the images. The architecture of FESTIVAL is such that it is easy to add support for other instruments and these new data immediately benefit from the already existing capabilities. Also, because its mapping engine is fully 3D, FESTIVAL provides a convenient environment to display images from future out-of-the-Ecliptic solar missions, such as Solar Orbiter or Solar Probe. Title: A Time-Evolving 3D Method Dedicated to the Reconstruction of Solar Plumes and Results Using Extreme Ultraviolet Data Authors: Barbey, Nicolas; Auchère, Frédéric; Rodet, Thomas; Vial, Jean-Claude Bibcode: 2008SoPh..248..409B Altcode: 2008SoPh..tmp...65B; 2008arXiv0802.0113B An important issue in the tomographic reconstruction of the solar poles is the relatively rapid evolution of the polar plumes. We demonstrate that it is possible to take into account this temporal evolution in the reconstruction. The difficulty of this problem comes from the fact that we want a four-dimensional reconstruction (three spatial dimensions plus time) whereas we only have three-dimensional data (two-dimensional images plus time). To overcome this difficulty, we introduce a model that describes polar plumes as stationary objects whose intensity varies homogeneously with time. This assumption can be physically justified if one accepts the stability of the magnetic structure. This model leads to a bilinear inverse problem. We describe how to extend linear inversion methods to these kinds of problems. Studies of simulations show the reliability of our method. Results for SOHO/EIT data show that we can estimate the temporal evolution of polar plumes to improve the reconstruction of the solar poles from only one point of view. We expect further improvements from STEREO/EUVI data when the two probes will be separated by about 60°. Title: Sun Earth Connection Coronal and Heliospheric Investigation (SECCHI) Authors: Howard, R. A.; Moses, J. D.; Vourlidas, A.; Newmark, J. S.; Socker, D. G.; Plunkett, S. P.; Korendyke, C. M.; Cook, J. W.; Hurley, A.; Davila, J. M.; Thompson, W. T.; St Cyr, O. C.; Mentzell, E.; Mehalick, K.; Lemen, J. R.; Wuelser, J. P.; Duncan, D. W.; Tarbell, T. D.; Wolfson, C. J.; Moore, A.; Harrison, R. A.; Waltham, N. R.; Lang, J.; Davis, C. J.; Eyles, C. J.; Mapson-Menard, H.; Simnett, G. M.; Halain, J. P.; Defise, J. M.; Mazy, E.; Rochus, P.; Mercier, R.; Ravet, M. F.; Delmotte, F.; Auchere, F.; Delaboudiniere, J. P.; Bothmer, V.; Deutsch, W.; Wang, D.; Rich, N.; Cooper, S.; Stephens, V.; Maahs, G.; Baugh, R.; McMullin, D.; Carter, T. Bibcode: 2008SSRv..136...67H Altcode: 2008SSRv..tmp...64H The Sun Earth Connection Coronal and Heliospheric Investigation (SECCHI) is a five telescope package, which has been developed for the Solar Terrestrial Relation Observatory (STEREO) mission by the Naval Research Laboratory (USA), the Lockheed Solar and Astrophysics Laboratory (USA), the Goddard Space Flight Center (USA), the University of Birmingham (UK), the Rutherford Appleton Laboratory (UK), the Max Planck Institute for Solar System Research (Germany), the Centre Spatiale de Leige (Belgium), the Institut d’Optique (France) and the Institut d’Astrophysique Spatiale (France). SECCHI comprises five telescopes, which together image the solar corona from the solar disk to beyond 1 AU. These telescopes are: an extreme ultraviolet imager (EUVI: 1 1.7 R), two traditional Lyot coronagraphs (COR1: 1.5 4 R and COR2: 2.5 15 R) and two new designs of heliospheric imagers (HI-1: 15 84 R and HI-2: 66 318 R). All the instruments use 2048×2048 pixel CCD arrays in a backside-in mode. The EUVI backside surface has been specially processed for EUV sensitivity, while the others have an anti-reflection coating applied. A multi-tasking operating system, running on a PowerPC CPU, receives commands from the spacecraft, controls the instrument operations, acquires the images and compresses them for downlink through the main science channel (at compression factors typically up to 20×) and also through a low bandwidth channel to be used for space weather forecasting (at compression factors up to 200×). An image compression factor of about 10× enable the collection of images at the rate of about one every 2 3 minutes. Identical instruments, except for different sizes of occulters, are included on the STEREO-A and STEREO-B spacecraft. Title: Review on the solar spectral variability in the EUV for space weather purposes Authors: Lilensten, J.; Dudok de Wit, T.; Kretzschmar, M.; Amblard, P. -O.; Moussaoui, S.; Aboudarham, J.; Auchère, F. Bibcode: 2008AnGeo..26..269L Altcode: The solar XUV-EUV flux is the main energy source in the terrestrial diurnal thermosphere: it produces ionization, dissociation, excitation and heating. Accurate knowledge of this flux is of prime importance for space weather. We first list the space weather applications that require nowcasting and forecasting of the solar XUV-EUV flux. We then review present models and discuss how they account for the variability of the solar spectrum. We show why the measurement of the full spectrum is difficult, and why it is illusory to retrieve it from its atmospheric effects. We then address the problem of determining a set of observations that are adapted for space weather purposes, in the frame of ionospheric studies. Finally, we review the existing and future space experiments that are devoted to the observation of the solar XUV-EUV spectrum. Title: Polarisation and magnetic depolarization of the Lyman-alpha line in the corona : the line-of-sight effects Authors: Vial, Jean-Claude; Derouich, Moncef; Auchere, Frederic; Zhang, Mei Bibcode: 2008cosp...37.3340V Altcode: 2008cosp.meet.3340V In view of the importance of measuring coronal magnetic field and of the capability of measuring linear polarization in the Lyman α line with the LYOT coronagraph on board the SMESE mission, we carried out some calculations of the degrees of depolarization resulting from the presence of a magnetic field. Our calculation is based on a simple magnetic field model where a current sheet in the field represents a solar prominence. We focus in this study on the effect of the line-of-sight integration at various locations in the corona on the polarizing/depolarizing properties. Other magnetic configurations are also considered and are under the study. Title: The EUV Sun as a superposition of 3 elementary Suns Authors: Dudok de Wit, Thierry; Kretzschmar, Matthieu; Moussaoui, Saïd; Amblard, Pierre-Olivier; Lilensten, Jean; Auchere, Frederic; Aboudarham, Jean Bibcode: 2008cosp...37..763D Altcode: 2008cosp.meet..763D Many studies assume that the solar irradiance in the EUV can be decomposed into different contributions, which considerably eases the modelling of the spectral variability for thermosphere/ionosphere models. We consider a different approach, in which these contributions are not imposed a priori but inferred from the spectral irradiance measurements. This problem can be considered as a source separation problem with positivity constraint, for which we use a recent Bayesian method. Using five years of daily EUV spectra recorded by the SEE instrument onboard TIMED, we show that the spectral irradiance can be decomposed into three elementary spectra. The first one is associated with the quiet Sun, the second one with active regions, whereas the third one captures the cold contribution from the chromosphere. Title: SMESE (SMall Explorer for Solar Eruptions): A microsatellite mission with combined solar payload Authors: Vial, J. -C.; Auchère, F.; Chang, J.; Fang, C.; Gan, W. Q.; Klein, K. -L.; Prado, J. -Y.; Rouesnel, F.; Sémery, A.; Trottet, G.; Wang, C. Bibcode: 2008AdSpR..41..183V Altcode: The SMESE (SMall Explorer for Solar Eruptions) mission is a microsatellite proposed by France and China. The payload of SMESE consists of three packages: LYOT (a Lyman α imager and a Lyman α coronagraph), DESIR (an Infra-red Telescope working at 35 80 and 100 250 μm), and HEBS (a High Energy Burst Spectrometer working in X- and gamma-rays). The scientific objectives of the mission are shortly presented. We describe the three instrumental packages and the profile of the mission which accommodates them. With a launch around 2012 2013, the SMESE microsatellite mission will provide a unique tool for detecting and understanding eruptions (flares and coronal mass ejections). Observations should start around solar maximum, and continue in the declining phase of activity, at a time when the Solar Dynamics Observatory (SDO) should still be operating. Title: The SECCHI Experiment on the STEREO Mission Authors: Howard, R. A.; Moses, J. D.; Vourlidas, A.; Newmark, J. S.; Socker, D. G.; Wang, D.; Plunkett, S. P.; Baugh, R.; McMullin, D. R.; Davila, J. M.; Thompson, W. T.; Lemen, J. R.; Wuelser, J.; Harrison, R. A.; Waltham, N. R.; Davis, C. J.; Eyles, C. J.; Defise, J.; Halain, J.; Bothmer, V.; Delaboudiniere, J.; Auchere, F.; Mercier, R.; Ravet, M. F. Bibcode: 2007AGUSMSH33A..01H Altcode: The Sun Earth Connection Coronal and Heliospheric Investigation (SECCHI) on the NASA Solar Terrestrial Relations Observatory (STEREO) mission is a suite of remote sensing instruments consisting of an extreme ultraviolet (EUV) imager, two white light coronagraphs, and two telescopes that comprise the heliospheric imager. SECCHI will observe coronal mass ejections (CMEs) from their birth at the sun, through the corona and into the heliosphere. A complete instrument suite is being carried on each of the two STEREO spacecraft, which will provide the first sampling of a CME from two vantage points. The spacecraft, launched 25 October 2006, are orbiting the Sun, one Ahead of the Earth and the other Behind, each separating from Earth at about 22 degrees per year. The varying separation means that we will have different observational capabilities as the spacecraft separate and therefore differing science goals. The primary science objectives all are focused on understanding the physics of the CME process their initiation, 3D morphology, propagation, interaction with the interplanetary medium and space weather effects. By observing the CME from multiple viewpoints with UV and coronagraphic telescopes and by combining these observations with radio and in-situ observations from the other instruments on STEREO as well as from other satellites and ground based observatories operating at the same time, answers to some of the outstanding questions will be obtained. We will show some of the initial results. Title: Stereo Observations Of The Solar Corona Using The Secchi Experiment Authors: Plunkett, Simon P.; Howard, R. A.; Moses, J. D.; Vourlidas, A.; Socker, D.; Newmark, J.; Wang, D.; Baugh, R.; Davila, J.; Thompson, W.; St. Cyr, O. C.; Lemen, J.; Wuelser, J. P.; Harrison, R. A.; Waltham, N.; Davis, C. J.; Eyles, C. J.; Defise, J. M.; Halain, J. P.; Bothmer, V.; Delaboudiniere, J. P.; Auchere, F.; Mercier, R.; Ravet, M. F. Bibcode: 2007AAS...21011901P Altcode: 2007BAAS...39..243P The Sun Earth Connection Coronal and Heliospheric Investigation (SECCHI) on the NASA Solar Terrestrial Relations Observatory (STEREO) mission is a suite of remote sensing instruments consisting of an extreme ultraviolet (EUV) imager, two white light coronagraphs, and two telescopes that comprise the heliospheric imager. The main objective of SECCHI is to observe coronal mass ejections (CMEs) from their birth at the sun, through the corona and into the heliosphere. A complete instrument suite is being carried on each of the two STEREO spacecraft, which will provide the first sampling of a CME from two vantage points as the spacecraft separate from each other at the rate of about 45 degrees per year. We will show examples of some of the data and some of the initial stereo results. Title: Multispectral analysis of solar EUV images: linking temperature to morphology Authors: Dudok de Wit, T.; Auchère, F. Bibcode: 2007A&A...466..347D Altcode: 2007astro.ph..2052D Context: Solar images taken simultaneously at different wavelengths in the EUV are widely used for understanding structures such as flares, coronal holes, loops, etc. The line-of-sight integration and the finite spectral resolution of EUV telescopes, however, hinders interpretation of these individual images in terms of temperature bands. Traditional approaches involve simple visualisation or explicit modelling. We take a more empirical approach, using statistical methods.
Aims: The morphology of solar structures changes with the wavelength of observation and, therefore, with temperature. We explore the possibility of separating the different solar structures from a linear combination of images.
Methods: Using a blind source separation approach, we build a new set of statistically independent "source" images from the original EUV images. Two techniques are compared: the singular value decomposition and independent component analysis.
Results: The source images show more contrast than the original ones, thereby easing the characterisation of morphological structures. A comparison with the differential emission measure shows that each source image also isolates structures with specific emission temperatures. Title: SMESE: A SMall Explorer for Solar Eruptions Authors: Vial, J. -C.; Auchère, F.; Chang, J.; Fang, C.; Gan, W. Q.; Klein, K. -L.; Prado, J. -Y.; Trottet, G.; Wang, C.; Yan, Y. H. Bibcode: 2007AdSpR..40.1787V Altcode: The SMall Explorer for Solar Eruptions (SMESE) mission is a microsatellite proposed by France and China. The payload of SMESE consists of three packages: LYOT (a Lyman α imager and a Lyman α coronagraph), DESIR (an Infra-Red Telescope working at 35-80 and 100-250 μm), and HEBS (a High-Energy Burst Spectrometer working in X- and γ-rays). The status of research on flares and coronal mass ejections is briefly reviewed in the context of on-going missions such as SOHO, TRACE and RHESSI. The scientific objectives and the profile of the mission are described. With a launch around 2012-2013, SMESE will provide a unique tool for detecting and understanding eruptions (flares and coronal mass ejections) close to the maximum phase of activity. Title: EUI, The Ultraviolet Imaging Telescopes Of Solar Orbiter Authors: Hochedez, J. -F.; Appourchaux, T.; Defise, J. -M.; Harra, L. K.; Schühle, U.; Auchère, F.; Curdt, W.; Hancock, B.; Kretzschmar, M.; Lawrence, G.; Leclec'h, J. -C.; Marsch, E.; Mercier, R.; Parenti, S.; Podladchikova, E.; Ravet, M. -F.; Rochus, P.; Rodriguez, L.; Rouesnel, F.; Solanki, S.; Teriaca, L.; Van Driel, L.; Vial, J. -C.; Winter, B.; Zhukov, A. Bibcode: 2007ESASP.641E..33H Altcode: The scientific objectives of Solar Orbiter rely ubiquitously on EUI, its suite of solar atmosphere imaging telescopes. In the configuration discussed here, EUI includes three co-aligned High Resolution Imagers (HRI) and one Full Sun Imager (FSI). FSI and two HRIs observe in extreme ultraviolet passbands, dominated by coronal emission. Another HRI is designed for the hydrogen Lyman α radiation in the far UV, imaging the Chromosphere and the lower Transition Region. The current EUI design and some of its development challenges are highlighted. EUI profits from co-rotation phases, solar proximity and departure from the ecliptic. In synergy with the other S.O. payload, EUI probes the dynamics of the solar atmosphere, provides context data for all investigations and helps to link in-situ and remote-sensing observations. In short, it serves all four top-level goals of the mission. For these reasons, the EUI suite is keenly anticipated in the European scientific community and beyond. Title: The SECCHI Experiment on the STEREO Mission Authors: Howard, R. A.; Moses, D.; Vourlidas, A.; Newmark, J.; Socker, D. G.; Plunkett, S.; Wang, D.; Baugh, R.; McMullin, D.; Davila, J.; St. Cyr, C.; Thompson, W. T.; Lemen, J.; Wuelser, J.; Harrison, R. A.; Waltham, N. R.; Davis, C.; Eyles, C. J.; Defise, J.; Halain, J.; Bothmer, V.; Delaboudiniere, J.; Auchere, F.; Mercier, R.; Ravet, M. Bibcode: 2006AGUFMSM12A..02H Altcode: The Sun Earth Connection Coronal and Heliospheric Investigation (SECCHI) on the NASA Solar Terrestrial Relations Observatory (STEREO) mission is a suite of remote sensing instruments consisting of an extreme ultraviolet (EUV) imager, two white light coronagraphs, and two telescopes that comprise the heliospheric imager. SECCHI will observe coronal mass ejections (CMEs) from their birth at the sun, through the corona and into the heliosphere. A complete instrument suite is being carried on each of the two STEREO spacecraft, which will provide the first sampling of a CME from two vantage points. The spacecraft will orbit the Sun, one Ahead of the Earth and the other Behind, each separating from Earth at about 22 degrees per year. The varying separation means that we will have different observational capabilities as the spacecraft separate and therefore differing science goals. The primary science objectives all are focused on understanding the physics of the CME process their initiation, 3D morphology, propagation, interaction with the interplanetary medium and space weather effects. By observing the CME from multiple viewpoints with UV and coronagraphic telescopes and by combining these observations with radio and in-situ observations from the other instruments on STEREO as well as from other satellites and ground based observatories operating at the same time, answers to some of the outstanding questions will be obtained. STEREO follows the very successful SOHO mission. SOHO's success was primarily due to the highly complementary nature of the instruments, but it was partly due to the very stable platform. The L1 orbit enables an extremely stable thermal environment and thus very stable pointing, as well as uninterrupted solar viewing. The STEREO will have both of these characteristics, but in addition will have multi-viewpoint viewing of CMEs, which will greatly enhance the many discoveries that SOHO data have produced. We have been developing techniques to interpret the observations from multiple viewpoints and to perform 3-dimensional deconvolution of the CME observations using forward modeling and inversion techniques. A continuous downlink of STEREO data will provide a low-resolution, real- time view from all of the instruments. The full data are downlinked once a day and will be available about 24 hours later. We will present some preliminary results from the instrument, which is expected to be launched in October/November, 2006 Title: Rotational Tomography of the Solar Corona-Calculation of the Electron Density and Temperature Authors: Barbey, Nicolas; Auchère, Frédéric; Rodet, Thomas; Bocchialini, Karine; Vial, Jean-Claude Bibcode: 2006ESASP.617E..82B Altcode: 2006soho...17E..82B No abstract at ADS Title: Helium/Hydrogen Fractionation in the Solar Wind-How Much is Due to Inefficient Coulomb Drag? Authors: Bochsler, P.; Auchère, F.; Skoug, R. M. Bibcode: 2006ESASP.617E..28B Altcode: 2006soho...17E..28B No abstract at ADS Title: SMESE: a combined UV-IR-X-gamma solar mission Authors: Millard, Anne A.; Auchere, Frederic; Fang, Cheng; Gan, Weiqun; Molodij, Guillaume; Prado, Jean-Yves; Rouesnel, Frederic; Semery, Alain; Trottet, Gerard; Vial, Jean-Claude; Yan, Yihua; Wu, Ji Bibcode: 2006SPIE.6266E..0JM Altcode: 2006SPIE.6266E..15M SMESE (SMall Explorer For the study of Solar Eruptions) is a Franco-Chinese microsatellite mission. The scientific objectives of SMESE are the study of coronal mass ejections and flares. Its payload consists of three instrument packages : LYOT, DESIR and HEBS. LYOT is composed of a Lyman α (121.6 nm) coronagraph, a Lyman α disk imager and a far UV disk imager. DESIR is an infrared telescope working at 35 μm and 150 μm. HEBS is a high energy burst spectrometer working in X rays and γ rays covering the 10 keV to 600 MeV range. SMESE will be launched around 2011, providing a unique opportunity of detecting and understanding eruptions at the maximum activity phase of the solar cycle in a wide range of energies. The instrumentation on board SMESE is described in this paper. Title: From the Sun to the Earth: impact of the 27-28 May 2003 solar events on the magnetosphere, ionosphere and thermosphere Authors: Hanuise, C.; Cerisier, J. C.; Auchère, F.; Bocchialini, K.; Bruinsma, S.; Cornilleau-Wehrlin, N.; Jakowski, N.; Lathuillère, C.; Menvielle, M.; Valette, J. -J.; Vilmer, N.; Watermann, J.; Yaya, P. Bibcode: 2006AnGeo..24..129H Altcode: During the last week of May 2003, the solar active region AR 10365 produced a large number of flares, several of which were accompanied by Coronal Mass Ejections (CME). Specifically on 27 and 28 May three halo CMEs were observed which had a significant impact on geospace. On 29 May, upon their arrival at the L1 point, in front of the Earth's magnetosphere, two interplanetary shocks and two additional solar wind pressure pulses were recorded by the ACE spacecraft. The interplanetary magnetic field data showed the clear signature of a magnetic cloud passing ACE. In the wake of the successive increases in solar wind pressure, the magnetosphere became strongly compressed and the sub-solar magnetopause moved inside five Earth radii. At low altitudes the increased energy input to the magnetosphere was responsible for a substantial enhancement of Region-1 field-aligned currents. The ionospheric Hall currents also intensified and the entire high-latitude current system moved equatorward by about 10°. Several substorms occurred during this period, some of them - but not all - apparently triggered by the solar wind pressure pulses. The storm's most notable consequences on geospace, including space weather effects, were (1) the expansion of the auroral oval, and aurorae seen at mid latitudes, (2) the significant modification of the total electron content in the sunlight high-latitude ionosphere, (3) the perturbation of radio-wave propagation manifested by HF blackouts and increased GPS signal scintillation, and (4) the heating of the thermosphere, causing increased satellite drag. We discuss the reasons why the May 2003 storm is less intense than the October-November 2003 storms, although several indicators reach similar intensities. Title: Can the EUV spectrum and its variability be reconstructed from a small set of spectral lines ? Authors: Dudok de Wit, T.; Lilensten, J.; Aboudarham, J.; Amblard, P. -O.; Auchère, F.; Kretzschmar, M. Bibcode: 2006cosp...36..991D Altcode: 2006cosp.meet..991D The severe lack of continuously measured and spectrally resolved solar EUV spectra is a major obstacle towards modelling the impact of the solar irradiance on the ionosphere The usual solution involves the measurement of various proxies We consider a different approach in which the EUV spectrum and its variability are reconstructed from the linear combination of a few spectral lines Using three years of spectra from TIMED and a statistical classification technique we demonstrate that 5 to 8 lines only are needed and in addition show which lines are the best candidates These results are valuable for instrument specification and also provide new insight into the comparison of solar proxies against the EUV irradiance Title: A brief introduction to SMESE mission Authors: Wang, C.; Fang, C.; Gan, W.; Prado, J. -Y.; Trottet, G.; Vial, J. -C.; Yan, Y.; Auchere, F.; Chang, J.; Molodi, G. Bibcode: 2006ilws.conf..211W Altcode: Small Exploration for Solar Eruptions (SMESE) is a joint mission between France and China to investigate the two main types of eruption events on the Sun: Coronal Mass Ejections (CME) and solar flares, and their relationship. SMESE will provide a set of unprecedented and complementary measurements including Ly-alpha imager, Ly-alpha coronagraph, EUV imager, Detection of Solar Infra red radiation, Hard X-ray/gamma ray spectrometry. SMESE aims to study, among others, the CME triggering mechanism and its acceleration in the corona, the particle acceleration by CME and solar flare, the physical association of the CME and solar flare etc. SMESE will be launched in the next solar maximum between 2010-2012. Title: SMESE, a SMall Explorer for the Study of solar Eruptions Authors: Vial, J. -C.; Auchère, F.; Chang, J.; Fang, C.; Gan, W. Q.; Molodij, G.; Prado, J. -Y.; Trottet, G.; Wang, C.; Yan, Y. H. Bibcode: 2006cosp...36.3287V Altcode: 2006cosp.meet.3287V The SMESE Small Explorer for the Study of solar Eruptions mission is a microsatellite proposed by France and China The payload of SMESE consists of three packages LYOT a suite of two UV and EUV imagers and a Lyman alpha coronagraph DESIR an Infra-Red Telescope working at 35 and 150 mu and HEBS a High Energy Burst Spectrometer working in X- and gamma -rays The status of research on Coronal Mass Ejections and flares will be briefly recalled in the context of on-going missions such as SOHO TRACE and RHESSI The scientific objectives and the profile of the mission will be described With a launch around 2011 SMESE will provide a unique tool for detecting and understanding eruptions flares and coronal mass ejections in the maximum phase of activity when the Solar Dynamics Observatory SDO should still be operating Title: SMESE: a Small Explorer for the Study of Solar Eruptions Authors: Vial, J. -C.; Auchère, F.; Chang, J.; Fang, C.; Gan, W. Q.; Molodij, G.; Prado, J. -Y.; Trottet, G.; Wang, C.; Yan, Y. H. Bibcode: 2006cosp...36.3294V Altcode: 2006cosp.meet.3294V The SMESE Small Explorer for the Study of solar Eruptions mission is a microsatellite proposed by France and China The payload of SMESE consists of three packages LYOT a suite of two UV and EUV imagers and a Lyman alpha coronagraph DESIR an Infra-Red Telescope working at 35 and 150 mu and HEBS a High Energy Burst Spectrometer working in X- and gamma -rays The status of research on Coronal Mass Ejections will be briefly recalled in the context of on-going missions such as SOHO TRACE and RHESSI The scientific objectives and the profile of the mission will be described With a launch around 2011 SMESE will provide a unique tool for detecting and understanding eruptions flares and coronal mass ejections in the maximum phase of activity and for the determination of the morphology of the low corona from where the solar wind originates Title: An atlas of solar events: 1996 2005 Authors: Artzner, G.; Auchère, F.; Delaboudinière, J. P.; Bougnet, M. Bibcode: 2006AdSpR..38..390A Altcode: Coronal mass ejections (CMEs) are observed in the plane of the sky in coronographic images. As the solar surface is masked by an occulting disk it is not clear whether halo CMEs are directed towards or away from the Earth. Observations of the solar corona on the solar disk by the extreme ultraviolet imaging telescope (EIT) on board the Solar Heliospheric Observatory SoHO can help to resolve this. Quasi-continuous observations of the solar corona were obtained from April 1997 up to the current date at a 12 min cadence in the coronal line of FeXII, as part of a “CME watch program”. At a slower 6 h cadence an additional synoptic program investigates the chromosphere and the corona at four different wavelengths. Large coronal solar events appear when viewing animations of the CME watch program. Fainter events do appear when viewing running difference animations of the CME watch program. When looking for additional spectral information from raw running differences of the synoptic program it is difficult to disentangle intrinsic solar events from the parasitic effect of the solar rotation. We constructed at www.ias.u-psud.fr/medoc/EIT/movies/ an atlas of more than 40,000 difference images from the synoptic programme, corrected for an average solar rotation, as well as more than 200,000 instantaneous and difference images from the CME watch program. We present case studies of specific events in order to investigate the source of darkenings or dimmings in difference images, due to the removal of emitting material, the presence of obscuring material or large changes in temperature. As the beneficial effect of correcting for the solar rotation vanishes at the solar limb, we do not investigate the case of prominence Doppler dimming. As a by-product of the atlas of solar events we obtain a number of quiet time sequences well suited to precisely measure the differential solar rotation by the apparent displacement of tracers. Title: The Beleinos cornerstone: the Sun, the star close to Earth Authors: Appourchaux, T.; Auchère, F.; Bocchialini, K.; Bonnet, R. M.; Gabriel, A.; Vial, J. -C. Bibcode: 2005ESASP.588..389A Altcode: 2005tssc.conf..389A No abstract at ADS Title: Observations of Solar EUV Radiation with the CORONAS-F/SPIRIT and SOHO/EIT Instruments Authors: Slemzin, V. A.; Kuzin, S. V.; Zhitnik, I. A.; Delaboudiniere, J. -P.; Auchere, F.; Zhukov, A. N.; van der Linden, R.; Bugaenko, O. I.; Ignat'ev, A. P.; Mitrofanov, A. V.; Pertsov, A. A.; Oparin, S. N.; Stepanov, A. I.; Afanas'ev, A. N. Bibcode: 2005SoSyR..39..489S Altcode: The SPIRIT complex onboard the CORONAS-F satellite has routinely imaged the Sun in the 171, 175, 195, 284, and 304 Å spectral bands since August 2001. The complex incorporates two telescopes. The Ritchey-Chretien telescope operates in the 171, 195, 284, and 304 Å bands and has an objective similar to that of the SOHO/EIT instrument. The Herschel telescope obtains solar images synchronously in the 175 and 304 Å bands with two multilayer-coated parabolic mirrors. The SPIRIT program includes synoptic observations, studies of the dynamics of various structures on the solar disk and in the corona up to 5 solar radii, and coordinated observations with other spaceborne and ground-based telescopes. In particular, in the period 2002-2003, synoptic observations with the SPIRIT Ritchey-Chretien telescope were coordinated with regular 6-hour SOHO/EIT observations. Since June 2003, when EIT data were temporarily absent ( SOHO keyholes), the SPIRIT telescope has performed synoptic observations at a wavelength of 175 A. These data were used by the Solar Influence Data Analysis Center (SIDC) at the Royal Observatory of Belgium for an early space weather forecast. We analyze the photometric and spectral parameters of the SPIRIT and EIT instruments and compare the integrated (over the solar disk) EUV fluxes using solar images obtained with these instruments during the CORONAS-F flight from August 2001 through December 2003. Title: A Model for Solar EUV Flux Helium Photoionization Throughout the 3-Dimensional Heliosphere Authors: Auchère, F.; McMullin, D. R.; Cook, J. W.; Newmark, J. S.; von Steiger, R.; Witte, M. Bibcode: 2005ESASP.592..327A Altcode: 2005soho...16E..49A; 2005ESASP.592E..49A No abstract at ADS Title: EMMA: The EIT MPEG Movies Archive at the Multi Experiment Data Operation Center Authors: Auchère, F. Bibcode: 2005ESASP.592..671A Altcode: 2005ESASP.592E.133A; 2005soho...16E.133A No abstract at ADS Title: CORONAS-F/SPIRIT EUV observations of October-November 2003 solar eruptive events in combination with SOHO/EIT data Authors: Grechnev, V. V.; Chertok, I. M.; Slemzin, V. A.; Kuzin, S. V.; Ignat'ev, A. P.; Pertsov, A. A.; Zhitnik, I. A.; DelaboudinièRe, J. -P.; AuchèRe, F. Bibcode: 2005JGRA..110.9S07G Altcode: 2005JGRA..11009S07G The extraordinary solar activity of October-November 2003 manifested itself in many powerful eruptive events, including large coronal mass ejections (CMEs) and extremely powerful flares. A number of major events were accompanied by practically all known phenomena of the solar activity, both local and large-scale, and caused severe space weather disturbances. We study large-scale posteruptive activity manifestations on the Sun associated with CMEs, i.e., dimmings and coronal waves, observed with extreme-ultraviolet telescopes, the SPIRIT on the CORONAS-F spacecraft and the EIT on the SOHO. During that period, observations with a cadence of 15 to 45 min were carried out by the SPIRIT in the 175 Å and 304 Å bands simultaneously. The EIT observed with 12-min cadence in the 195 Å band as well as with 6-hour cadence in the 171, 284, and 304 Å bands. These data complement each other both in the temporal and spectral coverage. Our analysis reveals that largest-scale dimmings covered almost the whole southern part of the Sun's visible side and exhibited homology, with one homological structure being changed to another configuration on 28 October. These structures show connections between large superactive and smaller regions that constituted a huge activity complex responsible for the extraordinary solar activity of that period. Coronal waves were observed at 175 Å as well as at 195 Å in some events, in areas where there were no active regions, but in the 175 Å images they look fainter. They were not accompanied by deep, long-living dimmings. By contrast, such dimmings were observed in active regions, in their vicinity, and between them. These facts rule out the direct relation of the phenomena of long-term dimmings and coronal waves. On 18 November, a motion of an ejecta was observed at the solar disk as a propagation of a dark feature only in the 304 Å band, which can be interpreted as an absorption in a "cloud" formed from material of the eruptive filament, which probably failed to become a CME core. Title: Formation flyers applied to solar coronal observations: the ASPICS mission Authors: Vives, S.; Lamy, P.; Auchere, F.; Vial, J. -C.; Koutchmy, S.; Arnaud, J.; Prado, J. -Y.; Frassetto, F.; Naletto, G. Bibcode: 2005SPIE.5901..305V Altcode: Classical externally-occulted coronagraphs are presently limited in their performances by the distance between the external occulter and the front objective. The diffraction fringe from the occulter and the vignetted pupil which degrades the spatial resolution prevent observing the inner corona inside typically 2-2.5 solar radii. Formation flyers open new perspectives and allow to conceive giant, externally-occulted coronagraphs using a two-component space system with the external occulter on one spacecraft and the optical instrument on the other spacecraft at approximately 100 m from the first one. ASPICS (Association de Satellites Pour l'Imagerie Coronographique Solaire) is a mission proposed to CNES in the framework of their demonstration program of formation flyers which is presently under study to exploit this technique for coronal observations. In the baseline concept, ASPICS includes three coronagraphs operating in three spectral domains: the visible continuum (K-corona brightness), the HI Lyman alpha emission line at 121.6 nm, and the HeII emission line at 30.4 nm. Their unvignetted fields of view extend from 1.1 to 3.2 solar radii with a typical spatial resolution of 3 arcsec. In order to connect coronal activity to photospheric events, ASPICS further includes two disk imagers. The first one is devoted to the HI Lyman alpha emission line. The second one is a multi-channel instrument similar to SOHO/EIT and devoted to the HeII (30.4 nm), FeIX/X (17.1 nm) and FeXII (19.5 nm) emission lines. Two concepts of the space system are under consideration: a symmetric configuration where the disk imagers and the external occulter are on one spacecraft and the coronagraphs on the other, an asymmetric configuration where the external occulter is on one spacecraft and the scientific instruments are regrouped on the other one. Title: Innovative designs for the imaging suite on Solar Orbiter Authors: Auchere, Frederic; Song, Xueyen; Rouesnel, Frederic; Appourchaux, Thierry; Fourmon, Jean-Jacques; Le Clec'h, Jean-Christophe; Berthe, Michel; Defise, Jean-Marc; Mazy, Emmanuel; Rochus, Pierre L.; Mercier, Raymond; Ravet, Marie-Francoise Bibcode: 2005SPIE.5901..298A Altcode: Orbiting around the Sun on an inclined orbit with a 0.2 UA perihelion, the Solar Orbiter probe will provide high resolution views of the Sun from various angles unattainable from Earth. Together with a set of high resolution imagers, the Full Sun Imager is part of the EUV Imaging suite of the Solar Orbiter mission. The mission's ambitious characteristics draw severe constraints on the design of these instruments. We present a photometrically efficient, compact, and lightweight design for the Full Sun Imager. With a 5 degrees field of view, this telescope will be able to see the global solar coronal structure from high viewing angles. Thermal solutions reducing the maximum power trapped in the High Resolution Imagers are also proposed. Title: The Heliospheric He II 30.4 nm Solar Flux During Cycle 23 Authors: Auchère, F.; Cook, J. W.; Newmark, J. S.; McMullin, D. R.; von Steiger, R.; Witte, M. Bibcode: 2005ApJ...625.1036A Altcode: Because of the orbit characteristics of the vast majority of spacecraft, the solar flux has predominantly been measured at Earth or at least in the plane of the ecliptic. Therefore, the existing data do not directly demonstrate the fact that the latitudinal distribution of the extreme-ultraviolet (EUV) solar flux is largely anisotropic. Indeed, in the EUV the nonuniform distribution of very contrasted bright features (i.e., active regions) and dark features (i.e., coronal holes) at the surface of the Sun produces both the obvious rotational (or longitudinal) modulation of the flux and also a strong latitudinal anisotropy. Although largely ignored up to now, the latitudinal anisotropy affects the physical conditions in the corona and heliosphere and should therefore be taken into account in several solar and heliospheric physics applications. We describe in this paper a technique for computing the He II 30.4 nm flux at an arbitrary position in the heliosphere from Solar and Heliospheric Observatory (SOHO) EUV Imaging Telescope (EIT) images. This procedure was used to produce daily all-sky maps of the 30.4 nm flux from 1996 January to 2003 August, covering the first 8 yr of solar cycle 23. As could be expected from the examination of the EIT images, the 30.4 nm flux was found to be strongly anisotropic. The anisotropy Ipol/Ieq between the fluxes computed for viewpoints located above the solar poles and within the solar equatorial plane ranges from 0.9 at solar minimum to 0.6 at solar maximum. A 20% difference was also discovered between the north and south polar fluxes. The generalization of this technique to other lines of the EUV and far-ultraviolet (FUV) spectrum is discussed. Title: Effect of the H I Lyα Chromospheric Flux Anisotropy on the Total Intensity of the Resonantly Scattered Coronal Radiation Authors: Auchère, F. Bibcode: 2005ApJ...622..737A Altcode: In modeling of the resonantly scattered solar coronal Lyα line of H I, the intensity of the chromospheric source is often assumed to be uniform. We investigate the validity of this assumption. After establishing a correlation between the H I 121.6 nm and He II 30.4 nm line intensities, we build Carrington maps of the Lyα chromosphere from SOHO EUV Imaging Telescope data. These maps are used to compute the Lyα irradiance throughout the corona and heliosphere. A 15% latitudinal anisotropy is found at 1 AU at solar minimum, and this value becomes larger closer to the Sun. The effect of the flux anisotropy on the total intensity of the Lyα resonantly scattered coronal radiation is quantified. We find that at solar minimum, the uniform-disk assumption leads to systematic overestimates of the total intensity of the polar regions by 15% on average. The evolution of this effect with solar activity and the case of other resonantly scattered coronal lines are discussed. Title: Model of the all-sky He II 30.4 nm solar flux Authors: Auchère, F.; Cook, J. W.; Newmark, J. S.; McMullin, D. R.; von Steiger, R.; Witte, M. Bibcode: 2005AdSpR..35..388A Altcode: Because of the orbit characteristics of the vast majority of spacecraft, the solar flux has been generally measured at Earth or in the plane of the ecliptic. So far, most published studies did not consider the fact that the extreme ultraviolet (EUV) solar flux is largely anisotropic. Indeed, in the EUV, the distribution of very contrasted bright and dark features at the surface of the Sun produces both the obvious rotational (longitudinal) modulation of the flux, but also a strong latitudinal anisotropy. Although largely ignored up to now, the latitudinal anisotropy affects the physical conditions in the corona and heliosphere. We describe an empirical model of the all-sky He II 30.4 nm flux based on EIT/ SOHO data. The 30.4 nm flux was found to be strongly anisotropic. The anisotropy Ipol/ Ieq between the fluxes computed for viewpoints located above the solar poles and within the solar equatorial plane ranges from 0.9 at solar minimum to 0.6 at solar maximum. A 20% asymmetry was also discovered between the north and south polar fluxes. Title: A Model For EUV Flux Throughout The 3-Dimensional Heliosphere Authors: McMullin, D. R.; Auchere, F.; Cook, J.; Newmark, J. S.; Quemerais, E.; von Steiger, R.; Witte, M. Bibcode: 2004AGUFMSH21B0423M Altcode: After July 2001, when Ulysses moved from 30 to 80 degrees in solar latitude, the Ulysses GAS instrument measured an apparent increase in the neutral He density. This is more naturally interpreted as a latitudinal dependence (decrease) of the loss rate due to solar photoionization rather than a true increase of the neutral He density. We have developed a three-dimensional model for solar EUV fluxes observed at any heliospheric position, using daily SOHO EIT observations, over successive Carrington rotations, projected to any heliospheric position. The combined effects of solar rotational and latitude-dependent flux variability are explicitly treated in this model. The flux model has been directly compared with other direct irradiance observations in the ecliptic plane with the SOHO/SEM irradiance time series for validation. We then use this flux to compute the photoionization rate of the in-flowing neutral He, and compare the modeled change with time along the spacecraft trajectory with the direct measurements from the out -of -ecliptic Ulysses GAS observations. The 3-D model developed will be directly applicable to STEREO EUV images from the SECCHI instrument suite. As the two spacecraft separate, the amount of the solar surface observed will increase through the mission, providing more accurate solar inputs. Title: HERSCHEL Suborbital Program: 3-D Applications for the STEREO Mission Authors: Moses, J. D.; Newmark, J.; McMullin, D.; Antonucci, E.; Fineschi, S.; Gardiol, D.; Zangrilli, L.; Romoli, M.; Pace, E.; Gori, L.; Landini, F.; Gherardi, A.; da Deppo, V.; Naletto, G.; Nicolosi, P.; Pelizzo, M.; Malvezzi, M.; Auchere, F.; Delaboudiniere, J.; Howard, R. Bibcode: 2004AGUFMSH23A..08M Altcode: The HERSCHEL (HElium Resonance Scatter in the Corona and HELiosphere) Suborbital Program is an international collaborative program between a consortium of Italian Universities & Observatories led by Dr. E. Antonucci (and funded by the Italian Space Agency, ASI), the French IAS (funded in part by CNES) and the Solar Physics Branch of NRL (by NASA SEC and the Office of Naval Research). HERSCHEL will: investigate the slow and fast solar wind, determine the helium distribution and abundance in the corona, and test solar wind acceleration models; by obtaining simultaneous observations of the electron, proton and helium solar coronae. HERSCHEL will also establish proof-of-principle for the Ultra-Violet Coronagraph, which is in the ESA Solar Orbiter Mission baseline. The HERSCHEL launch date has been linked to the STEREO launch date to allow coordinated science between the two missions. One aspect of this scientific coordination is establishing the 3-D structure of the inner corona. HERSCHEL provides a third viewpoint for the inner corona covered by the A&B STEREO SECCHI COR-1. HERSCHEL is the only scheduled, space-based asset that could provide this third viewpoint for the critical inner corona viewed by STEREO COR-1 (although lower resolution, ground-based cononagraphs will make a contribution). A third viewpoint dramatically increases one's ability to establish the 3-D structure of an optically thin object (e.g. the metric in Fig. 7 of Davila 1994, ApJ 423, 871). HERSCHEL will provide at least a snapshot of that viewpoint, plus a wide range of additional information on the H and He composition of the inner corona. Title: On the nature of EIT waves, EUV dimmings and their link to CMEs Authors: Zhukov, A. N.; Auchère, F. Bibcode: 2004A&A...427..705Z Altcode: EIT waves and extreme-ultraviolet (EUV) dimmings attract particular attention as they frequently accompany Coronal Mass Ejections (CMEs). We present several examples of EIT waves and EUV dimmings with particular morphologies previously unreported in the literature. We report for the first time an EIT wave in the Fe XV (284 Å) bandpass of the SOHO/EIT instrument. The observations of this event confirm previous results that an EIT wave is a purely coronal phenomenon that does not propagate in the transition region plasma. Two EIT wave events initiated close to the solar limb are investigated, thus permitting us to see simultaneously the wave and the magnetic configuration of the CME. These observations suggest that EIT wave can be regarded as a bimodal phenomenon. The wave mode represents a wave-like propagating disturbance. Its characteristic features are propagation of a bright front to large distances from dimming sites and quasi-circular appearance. The eruptive mode is the propagation of a dimming and of an EIT wave as a result of successive opening of magnetic field lines during the CME lift-off. It can be identified by noting the expansion of a dimming and the appearance of another dimming ahead of a bright front. We reveal the temperature structure of the EUV dimmings that appeared after the classical EIT wave event on May 12, 1997, using differential emission measure (DEM) maps obtained through the analysis of images in four EIT bandpasses. The part of the CME mass contained in the low corona observed by the EIT is estimated to be about 1015 g. It appears that around 50% of this total CME mass in the low corona is contained outside of transient coronal holes. It is shown that at present it is difficult to reconcile all the observational facts into a coherent physical model. In particular, the physical nature of the wave mode of EIT waves remains elusive.

Movies are available in electronic form at http://www.edpsciences.org Title: EIT Observations of the 15 November 1999 Mercury Transit Authors: Auchère, F.; Artzner, G. E. Bibcode: 2004SoPh..219..217A Altcode: The Mercury transit of 15 November 1999 has been observed from space by the SOHO and TRACE spacecraft. We exploited the data recorded by EIT/SOHO to determine the stray-light level and the plate-scale of the instrument. The asymmetric distribution of stray light across the images is confirmed, but the absolute amount was found to be higher than previously estimated. The plate scale averaged over wavelengths was found to be 2.627±0.001 arc sec pixel−1, in excellent agreement with two previous and independent determinations. Title: MAGRITTE: an instrument suite for the solar atmospheric imaging assembly (AIA) aboard the Solar Dynamics Observatory Authors: Rochus, Pierre L.; Defise, Jean-Marc; Halain, Jean-Philippe; Jamar, Claude A. J.; Mazy, Emmanuel; Rossi, Laurence; Thibert, Tanguy; Clette, Frederic; Cugnon, Pierre; Berghmans, David; Hochedez, Jean-Francois E.; Delaboudiniere, Jean-Pierre; Auchere, Frederic; Mercier, Raymond; Ravet, Marie-Francoise; Delmotte, Franck; Idir, Mourad; Schuehle, Udo H.; Bothmer, Volker; Fineschi, Silvano; Howard, Russell A.; Moses, John D.; Newmark, Jeffrey S. Bibcode: 2004SPIE.5171...53R Altcode: The Solar Atmospheric Imaging Assembly (AIA) aboard the Solar Dynamics Observatory will characterize the dynamical evolution of the solar plasma from the chromosphere to the corona, and will follow the connection of plasma dynamics with magnetic activity throughout the solar atmosphere. The AIA consists of 7 high-resolution imaging telescopes in the following spectral bandpasses: 1215Å. Ly-a, 304 Å He II, 629 Å OV, 465 Å Ne VII, 195 Å Fe XII (includes Fe XXIV), 284 Å Fe XV, and 335 Å Fe XVI. The telescopes are grouped by instrumental approach: the MAGRITTE Filtergraphs (R. MAGRITTE, famous 20th Century Belgian Surrealistic Artist), five multilayer EUV channels with bandpasses ranging from 195 to 1216 Å, and the SPECTRE Spectroheliograph with one soft-EUV channel at OV 629 Å. They will be simultaneously operated with a 10-second imaging cadence. These two instruments, the electronic boxes and two redundant Guide Telescopes (GT) constitute the AIA suite. They will be mounted and coaligned on a dedicated common optical bench. The GTs will provide pointing jitter information to the whole SHARPP assembly. This paper presents the selected technologies, the different challenges, the trade-offs to be made in phase A, and the model philosophy. From a scientific viewpoint, the unique combination high temporal and spatial resolutions with the simultaneous multi-channel capability will allow MAGRITTE / SPECTRE to explore new domains in the dynamics of the solar atmosphere, in particular the fast small-scale phenomena. We show how the spectral channels of the different instruments were derived to fulfill the AIA scientific objectives, and we outline how this imager array will address key science issues, like the transition region and coronal waves or flare precursors, in coordination with other SDO experiments. We finally describe the real-time solar monitoring products that will be made available for space-weather forecasting applications. Title: EUVI: the STEREO-SECCHI extreme ultraviolet imager Authors: Wuelser, Jean-Pierre; Lemen, James R.; Tarbell, Theodore D.; Wolfson, C. J.; Cannon, Joseph C.; Carpenter, Brock A.; Duncan, Dexter W.; Gradwohl, Glenn S.; Meyer, Syndie B.; Moore, Augustus S.; Navarro, Rosemarie L.; Pearson, J. D.; Rossi, George R.; Springer, Larry A.; Howard, Russell A.; Moses, John D.; Newmark, Jeffrey S.; Delaboudiniere, Jean-Pierre; Artzner, Guy E.; Auchere, Frederic; Bougnet, Marie; Bouyries, Philippe; Bridou, Francoise; Clotaire, Jean-Yves; Colas, Gerard; Delmotte, Franck; Jerome, Arnaud; Lamare, Michel; Mercier, Raymond; Mullot, Michel; Ravet, Marie-Francoise; Song, Xueyan; Bothmer, Volker; Deutsch, Werner Bibcode: 2004SPIE.5171..111W Altcode: The Extreme Ultraviolet Imager (EUVI) is part of the SECCHI instrument suite currently being developed for the NASA STEREO mission. Identical EUVI telescopes on the two STEREO spacecraft will study the structure and evolution of the solar corona in three dimensions, and specifically focus on the initiation and early evolution of coronal mass ejections (CMEs). The EUVI telescope is being developed at the Lockheed Martin Solar and Astrophysics Lab. The SECCHI investigation is led by the Naval Research Lab. The EUVI"s 2048 x 2048 pixel detectors have a field of view out to 1.7 solar radii, and observe in four spectral channels that span the 0.1 to 20 MK temperature range. In addition to its view from two vantage points, the EUVI will provide a substantial improvement in image resolution and image cadence over its predecessor SOHO-EIT, while complying with the more restricted mass, power, and volume allocations on the STEREO mission. Title: H/He+ intensity variations of the cool corona Authors: Noens, J. -C.; Balestat, M. -F.; Jimenez, R.; Rochain, S.; Romeuf, D.; Auchere, F.; Delaboudiniere, P.; Koutchmy, S. Bibcode: 2004IAUS..223..291N Altcode: 2005IAUS..223..291N No abstract at ADS Title: An atlas of solar events: 1997-2004 Authors: Artzner, G.; Auchère, F.; Delaboudinière, J. P.; Bougnet, M. Bibcode: 2004cosp...35.2494A Altcode: 2004cosp.meet.2494A Coronal mass ejections (CMEs) are observed in the plane of the sky from coronographic images. As the solar surface is then masked by an occulting disk, it is not clear wether halo CMEs are directed towards the Earth or in the opposite direction. Observations of the solar corona on the solar disk from the Extreme Ultraviolet Imaging Telescope EIT on board the Solar Heliospheric Observatory SoHO do help in order to make a choice. Quasi-continuous observations of the corona of the Sun have been therefore obtained from april 1997 up to now at a twelve minute cadence in the coronal line of FeXII, as a CME watch program. At a slower six hours cadence an additional synoptic program investigates the chromosphere and the corona at four different wavelengths. Large coronal solar events appear when viewing animations of the CME watch program. Fainter events do appear when viewing running difference animations of the CME watch program. When looking for additional spectral information from raw running differences of the synoptic program it is difficult to disentangle intrinsic solar events from the parasitic effect of the solar rotation. We constructed from the synoptic program observations an atlas of more than 20 000 difference images corrected for an average solar rotation. We present case studies of specific events in order to investigate the source of darkenings in difference images, either removal of emitting material, interposition of obscuring material or large changes of temperature. Statistics of brigtenings and darkenings along solar cycle 23 are presented. We speculate about future observations from the STEREO mission in order to obtain better diagnostics about darkenings. As a by product of the atlas of solar events we obtain a number of quiet time sequences well suited in order to precisely measure the differnetial solar rotation by the apparent displacement of tracers. Title: Model for 3-D Heliospheric EUV Irradiance and Photoionization Authors: Auchère, F.; McMullin, D.; Cook, J.; Newmark, J.; Vonsteiger, R.; Witte, M.; Quémerais, E. Bibcode: 2004cosp...35.2558A Altcode: 2004cosp.meet.2558A For 8 years now, the EIT instrument on board SOHO continuously monitored the solar activity in four passbands of the EUV spectrum. With the SOHO mission extended, it is likely that the final EIT data set will cover one complete solar cycle. This exceptional data set offers an unprecedented opportunity to investigate the long-term variations of the solar EUV irradiance. Furthermore, with the spatial resolution of the EIT/SOHO instrument, the data can also be used to study variations of the solar irradiance with heliocentric latitude. It is indeed clear that the wide intensity range of the various emitting regions (polar coronal holes, equatorial active regions, etc.) produces a latitude-dependant irradiance. To date, due to the small number of off-ecliptic measurements, very few attempts have been made to investigate these variations. We present here an empirical model of the EUV solar flux at any point in the heliosphere derived from EIT/SOHO data. At 30.4 nm, the anisotropy I_⊥ / I_∥ between the irradiance above (⊥) and within (∥) the ecliptic plane is found to range from about 0.8 at solar minimum to about 0.6 at solar maximum. Our anisotropic EUV fluxes are used to improve the present estimates of the photoionization rate of in-flowing neutral helium. These new rates are compared to the relative changes of neutral helium density measured by the GAS/Ulysses instrument. Title: The Ultraviolet and Visible-light Coronagraph of the HERSCHEL experiment Authors: Romoli, M.; Antonucci, E.; Fineschi, S.; Gardiol, D.; Zangrilli, L.; Malvezzi, M. A.; Pace, E.; Gori, L.; Landini, F.; Gherardi, A.; da Deppo, V.; Naletto, G.; Nicolosi, P.; Pelizzo, M. G.; Moses, J. D.; Newmark, J.; Howard, R.; Auchere, F.; Delaboudinière, J. P. Bibcode: 2003AIPC..679..846R Altcode: The Herschel (HElium Resonant Scattering in the Corona and HELiosphere) experiment, to be flown on a sounding rocket, will investigate the helium coronal abundance and the solar wind acceleration from a range of solar source structures by obtaining the first simultaneous observations of the electron, proton and helium solar corona. The HERSCHEL payload consists of the EUV Imaging Telescope (EIT), that resembles the SOHO/EIT instrument, and the Ultraviolet and Visible Coronagraph (UVC).UVC is an imaging coronagraph that will image the solar corona from 1.4 to 4 solar radii in the EUV lines of HI 121.6 nm and the HeII 30.4 nm and in the visible broadband polarized brightness. The UVC coronagraph is externally occulted with a novel design as far as the stray light rejection is concerned. Therefore, HERSCHEL will also establish proof-of-principle for the Ultraviolet Coronagraph, which is in the ESA Solar Orbiter Mission baseline.The scientific objectives of the experiment will be discussed, togetherwith a description of the UVC coronagraph. Title: The solar high-resolution imager - coronagraph LYOT mission Authors: Vial, Jean-Claude; Song, Xueyan; Lemaire, Philippe; Gabriel, Alan H.; Delaboudiniere, Jean-Pierre; Bocchialini, Karine; Koutchmy, Serge L.; Lamy, Philippe L.; Mercier, Raymond; Ravet, Marie Francoise; Auchere, Frederic Bibcode: 2003SPIE.4853..479V Altcode: The LYOT (LYman Orbiting Telescope) solar mission is proposed to be implemented on a micro-satellite of CNES (France) under phase A study. It includes two main instruments, which image the solar disk and the low corona up to 2.5 Ro in the H I Lyman-α line at 121.6 nm. The spatial resolution is about 1” for the disk and 2.5” for corona. It also carries an EIT-type telescope in the He II (30.4 nm) line. The coronagraph needs a super polished mirror at the entrance pupil to minimize the light scattering. Gratings and optical filters are used to select the Lyman-α wavelength. VUV cameras with 2048×2048 pixels record solar images up to every 10 seconds. The satellite operates at a high telemetry rate (more then 100 kb/s, after onboard data compression). The envisaged orbits are either geostationary or heliosynchronous. Possible launch dates could be end of 2006 - beginning of 2007. Title: MAGRITTE / SPECTRE : the Solar Atmospheric Imaging Assembly (AIA) aboard the Solar Dynamics Observatory Authors: Rochus, P.; Defise, J. M.; Halain, J. P.; Mazy, E.; Jamar, C.; Clette, F.; Cugnon, P.; Berghmans, D.; Hochedez, J. F.; Delaboudiniere, J. P.; Artzner, G.; Auchere, F.; Mercier, R.; Ravet, M. F.; Delmotte, M.; Idir, M.; Fineschi, S.; Antonucci, E.; Harrison, R. A.; Howard, R. A.; Moses, J. D.; Newmark, J. S. Bibcode: 2002AGUFMSH21C..05R Altcode: The Solar Atmospheric Imaging Assembly (AIA) aboard the Solar Dynamics Observatory will characterize the dynamical evolution of the solar plasma from the chromosphere to the corona, and will follow the connection of plasma dynamics with magnetic activity throughout the solar atmosphere. The AIA consists of 7 high resolution imaging telescopes in the following spectral bandpasses: 1215 \x8F Ly-a, 304 \x8F He II, 629 \x8F OV, 465 \x8F Ne VII, 195 \x8F Fe XII (includes Fe XXIV), 284 \x8F Fe XV, and 335 \x8F Fe XVI. The telescopes are grouped by instrumental approach: the Magritte Filtergraphs (R. Magritte, famous 20th Century Belgian Surrealistic Artist), five multilayer EUV channels with bandpasses ranging from 195 to 1216 \x8F, and the SPECTRE Spectroheliograph with one soft-EUV channel at OV 629 \x8F. They will be simultaneously operated with a 10-second imaging cadence. These two instruments, the electronic boxes and two redundant Guide Telescopes (GT) constitute the AIA suite. They will be mounted and coaligned on a dedicated common optical bench. The GTs will provide pointing jitter information to the whole SHARPP assembly. This poster presents the selected technologies, the different challenges, the trade-offs to be made in phase A, and the model philosophy. From a scientific viewpoint, the unique combination high temporal and spatial resolutions with the simultaneous multi-channel capability will allow Magritte/SPECTRE to explore new domains in the dynamics of the solar atmosphere, in particular the fast small-scale phenomena. We show how the spectral channels of the different instruments were derived to fulfill the AIA scientific objectives, and we outline how this imager array will address key science issues, like the transition region and coronal waves or flare precursors, in coordination with other SDO experiments. We finally describe the real-time solar monitoring products that will be made available for space-weather forecasting applications. Title: HElium Resonance Scattering in the Corona and HELiosphere (HERSCHEL) Authors: Moses, J. D.; Newmark, J.; Howard, R.; Auchere, F.; Antonucci, E.; Fineschi, S.; Romoli, M. Bibcode: 2002AGUSMSH21B..03M Altcode: The proposed HERSCHEL (HElium Resonance Scattering in the Corona and HELiosphere) program will investigate coronal heating and solar wind acceleration from a range of solar source structures by obtaining simultaneous observations of the electron, proton and helium solar coronae. The HERSCHEL will establish proof-of-principle for the Ultra-Violet Coronagraph (UVC), which is in the ESA Solar Orbiter Mission baseline. The NRL Solar Physics Branch is joining with the Italian UVC Consortium to address the objectives of the International Living With a Star program with this combination of NASA suborbital program and ESA Solar Orbiter flight opportunities. Indeed, while the Solar Orbiter flight is still many years away, the 3 year program being proposed here is essential in order to prove the validity of this exciting new concept before the Solar Orbiter instrument selection is finalized. This proposal aims to develop instrumentation that for the first time will directly image and characterize on a global coronal scale the two must abundant elements, hydrogen and helium. This will directly address three outstanding questions in the Sun-Earth Connection theme: 1) Origin of the slow solar wind, 2) Acceleration mechanisms of the fast solar wind, and 3) Variation of Helium abundance in coronal structures. Additionally, by establishing proof of concept for the UVC on Solar Orbiter, this will facilitate future investigations of CME's kinematics, and solar cycle evolution of the electron, proton, and helium coronae. Lastly, this mission fits the goals of the International Living With a Star (ILWS) program. This work has been supported by the Office of Naval Research. Title: The Radiometric Calibration of the Extreme Ultraviolet Imaging Telescope Authors: Clette, F.; Hochedez, J. -F.; Newmark, J. S.; Moses, J. D.; Auchère, F.; Defise, J. -M.; Delaboudinière, J. -P. Bibcode: 2002ISSIR...2..121C Altcode: 2002ESASR...2..121C; 2002rcs..conf..121C After a five-year effort, the analysis of the pre-flight and in-flight calibrations of EIT is finally yielding firm results. In this introductory overview, we will summarize what we learned "internally" from EIT itself. This includes the interpretation of the pre-flight calibrations, the original flat-field components (CCD, grid), the in-flight determination of the point-spread function and straylight and the compensation of the in-orbit response degradation. Based on this experience, we conclude with some suggestions of possible improvements to future calibrations, on SOHO and other planned missions. Title: SWRI/LASP Sounding Rocket Inter-Calibration With The Eit Instrument On Board SOHO Authors: Auchère, Frédéric; Hassler, Donald M.; Slater, David C.; Woods, Thomas N. Bibcode: 2001SoPh..202..269A Altcode: Two successful sounding rocket flights were launched on 15 May 1997 and 2 November 1998 with an objective of providing inter-calibration with several of the instruments on board SOHO and TRACE. We will discuss here the results of the inter-calibration between the SwRI/LASP rocket imaging instruments and the Extreme-ultraviolet Imaging Telescope (EIT) on SOHO. The Multiple XUV Imager (MXUVI) sounding rocket instrument is a multi-layer mirror telescope equipped with an internal occulter and light trap to provide full-disk images of Fe ix/x 17.1 nm and off-limb observations of He ii 30.4 nm. The SOHO/EIT instrument is also a full-disk multi-layer imager with four channels, Fe ix/x 17.1 nm, Fe xii 19.5 nm, Fe xv 28.4 nm and He ii 30.4 nm. By comparison with the EIT observations taken at the same time, we provide new flat-field determinations for EIT which help quantify the sensitivity degradation of the EIT detector, as well as provide a measure of the off-limb stray-light characteristics of the two instruments. We find that the EIT stray-light function is strongly asymmetric, with greater stray light in the 17.1 and 19.5 nm quadrants than the 30.4 and 28.4 nm quadrants. Two possible causes of this asymmetry are the polishing processes of the EIT mirrors and the asymmetric support grid pattern in the foil mesh at the EIT pupil. Title: The Height Variations of the Solar Chromosphere Authors: Auchère, F. Bibcode: 2001AGUSM..SH21B03A Altcode: We present a five year survey of the height of the solar chromosphere, as observed by the Extreme Ultraviolet Imaging Telescope (EIT) in its four bandpasses : 17.1 nm (FeIX/FeX), 19.5 nm (FeXII), 28.4 nm (FeXV), and 30.4 nm (HeII). Spatial pole-equator variations, as well as long-term temporal variations were investigated. The chromosphere was found to be prolate in all four wavelengths, with typical values of Δ D/D = 5x 10-3 in HeII and 1x 10-3 in the three iron lines. We found a very good correlation of the prolateness effect with the presence of polar coronal holes, and could follow its vanishing as the solar cycle peaked. The similitude between our results and previous observations made in various other lines suggest that the prolateness is a fundamental aspect of the solar atmosphere. Title: In-flight Calibration of SOHO EIT Authors: Newmark, J. S.; Cook, J. W.; Auchere, F.; Moses, J. D.; Clette, F. Bibcode: 2001AGUSM..SP21B06N Altcode: The SOHO EIT response has varied both temporally and spatially throughout the mission. A large effort has been put forth into understanding instrument responsivity changes, the spectral response and absolute calibration. The latter two have been completed (Dere et al. 2000, Newmark 2000). The response degradation process consists of several components which are difficult to separate in detail. The two basic processes contributing to the degradation are 1) the absorption of EUV before it interacts with the CCD by a surface contaminant plus possible blackening of the entrance filter and 2) the reduction of charge collection efficiency (CCE) in the CCD due to EUV induced device damage. A method utilizing the in-flight calibration lamps has been developed which accurately characterizes the sensitivity changes. We present absolutely calibrated SOHO EIT data from 1996 - 2000. Title: An Observational Study of Helium in the Solar Corona with the EIT Instrument on Board the SOHO Spacecraft Authors: Auchere, F. Bibcode: 2000PhDT........69A Altcode: Helium is the second most abundant element in the Universe. The understanding of the physicals processes associated with helium as well as the determination of the helium abundance both have implications in various research fields such as cosmology, stellar evolution or the physics of the solar wind. Helioseismology techniques give accurate measurements of the helium abundance in the solar interior, spectroscopic techniques provide diagnostics in the photosphere and in the chromosphere, and in situ measurements in the solar wind at 1 A.U. are carried out with particle detectors. But very few observations of helium exist in the corona and therefore, our knowledge of helium at intermediate distances between the photosphere and the solar wind is essentially based on theoretical studies. The present work is a tentative contribution to help constraint the observational knowledge of helium in the solar corona. The EIT telescope on board the SOHO spacecraft can observe the solar corona up to 2 Rs in an interval of wavelengths in the extreme ultraviolet spectrum including the resonance line of the He+ ion at 30.378 nm. This line being formed in the solar corona by resonant scattering of the chromospheric flux by coronal He+ ions, its intensity is proportional to the number density of He+ ions. Therefore, the observation of this line in the corona can potentially provide interesting diagnostics of the coronal helium. In spite of the contamination by other spectral lines, it seems that a non negligible fraction of the signal recorded by EIT in its 30.4 nm bandpass can be attribuated to the resonance line of He+. Furthermore, a preliminary study seems to show that the observed intensity gradients are anomalously low in the polar regions. The aim of the present work was to investigate further these preliminary results. We first carried out a detailed critical analysis of the characteristics of the EIT instrument in order to confirm that the 30.378 nm line of He+ in the corona can be detected in the 30.4 nm bandpass of EIT. This analysis implies a precise evaluation of several calibration parameters such as the flat-field of the detector, the contamination of the 30.4 nm bandpass and the instrumental stray light level. In order to interpret the intensities measured with EIT, we developed a model of the intensity of the resonance line of He+ in the corona, with the existing models for the Lyman alpha line of neutral hydrogen as a starting point. This model requires as an input some physical parameters such as the electron temperature and electron density, which were independently determined either from previous results or from new observations. The comparisons between the observed intensity and the prediction of the model seem to confirm the results of the preliminary analysis. In the equatorial regions, the intensity gradient of the resonance line of He+ is compatible with the electron density scale height. But at high latitudes in the polar coronal holes, the intensity gradient seems significatively smaller than what is expected from the computations. One can interpret this observation by an accumulation of helium in the polar coronal holes, where the fast solar wind originate. If the coronal ionisation balance computed in the model is valid, this accumulation of He+ could be the signature of an enhanced helium abundance in the corona. Some theoretical models of the corona/solar wind system show that the helium abundance could indeed be 20% or more in the corona, even though it is 10% in the solar interior and 4% in the solar wind. Because helium is four times more massive than hydrogen, it is clear the an enhanced helium abundance in the corona would greatly impact the energy and momentum uxes in the solar wind. However, further observations, especially with a better spectral resolution and a lower stray light level, are needed to confirm those of EIT. Title: Results from the 2 November 1998 SwRI/LASP Sounding Rocket Campaign Authors: Hassler, D. M.; Auchere, F.; Handy, B.; Strachan, L.; Slater, D.; Woods, T. N. Bibcode: 2000SPD....31.0216H Altcode: 2000BAAS...32..813H We present results from the November 2, 1998 SwRI/LASP sounding rocket campaign with the dual purpose of providing inter-calibration for the SOHO/EIT and TRACE instruments and providing a measure of the coronal helium abundance by direct comparison of the coronal Ly-alpha lines of He II (304 angstroms) and H I (1216 angstroms). The sounding rocket payload provided full-disk solar images of Fe IX/X 171 and H I Ly-alpha 1216 for inter-calibration with the SOHO/EIT and TRACE instruments, respectively, as well as off-limb observations of the He II 304 line to be compared with off-limb SOHO/UVCS observations of the H I 1216 line to provide a constraint on the coronal helium abundance. This work has been funded in part by NASA under grant NAG5-5140 to Southwest Research Institute. Title: In-Flight Determination of the Plate Scale of the Extreme-Ultraviolet Imaging Telescope Authors: Auchère, F.; DeForest, C. E.; Artzner, G. Bibcode: 2000ApJ...529L.115A Altcode: Using simultaneous observations of the Michelson Doppler Imager and Extreme-Ultraviolet Imaging Telescope (EIT) on board the Solar and Heliospheric Observatory spacecraft, we determined in flight the plate scale of the EIT. We found a value of 2.629"+/-0.001" pixel-1, in fair agreement with the 2.627"+/-0.001" pixel-1 value deduced from recent laboratory measurements of the focal length and much higher by 7 σ than the 2.622" pixel-1 value of the preflight calibrations. The plate scale is found to be constant across the field of view, confirming the negligible distortion level predicted by the theoretical models of the EIT. Furthermore, the 2 σ difference between our results and the latest laboratory measurements, although statistically small, may confirm a recent work suggesting that the solar photospheric radius may be 0.5 Mm lower than the classically adopted value of 695.99 Mm. Title: In Flight Determination of the Plate Scale of the EIT Authors: Auchere, F.; DeForest, C. E.; Artzner, G. Bibcode: 1999astro.ph.12213A Altcode: Using simultaneous observations of the MDI and EIT instruments on board the SoHO spacecraft, we determined in flight the plate scale of the EIT. We found a value of 2.629+-0.001 arc seconds per pixel, in fair agreement with the 2.627+-0.001 arc seconds per pixel value deduced from recent laboratory measurements of the focal length, and much higher by 7 sigma than the 2.622 arc seconds per pixel value of the pre-flight calibrations. The plate scale is found to be constant across the field of view, confirming the negligible distortion level predicted by the theoretical models of the EIT. Furthermore, the 2 sigma difference between our results and the latest laboratory measurements, although statistically small, may confirm a recent work suggesting that the solar photospheric radius may be 0.5 Mm lower than the classically adopted value of 695.99 Mm. Title: SwRI/LASP sounding rocket intercalibration with the EIT instrument on board SoHO Authors: Auchere, Frederic; Hassler, Donald M.; Slater, David C.; Woods, Thomas N. Bibcode: 1999SPIE.3765..351A Altcode: Two successful sounding rocket flights were launched on May 15, 1997 and November 2, 1998 with an objective of providing inter-calibration with several of the instruments on board SoHO and TRACE. We will discuss here the results of the inter-calibration between the SwRI/LASP rocket imaging instruments and the Extreme-UV Imaging Telescope (EIT) on SoHO. The MXUVI sounding rocket instrument is a multi-layer mirror telescope equipped with a special internal occulter and light trap to provide full disk imags of Fe IX/X 17.1 nm and off-limb observations of He II 30.4 nm. The SoHO/EIT instrument is also a full disk multi-layer imager with four channels, Fe IX/X 17.1 nm, FE XII 19.5 nm, Fe XV 28.4 nm and He II 30.4 nm. By comparison with the EIT observations taken at the same time we can quantify the sensitivity degradation of the EIT detector, as well as measure the off-limb stray- light characteristics of the two instruments. Title: The Prolate Solar Chromosphere Authors: Koutchmy, S.; di Folco, E.; Auchere, F.; Baudin, F.; Delaboudinière, J. -P.; Koutchmy, O.; Noëns, J. -C.; Rondi, S.; Jimemez, R.; Smartt, R. N. Bibcode: 1999ESASP.446..385K Altcode: 1999soho....8..385K The solar prolateness above h=2Mm is now well established from measurements performed during the years of solar minimum in HeII, Hα and K3CaII lines. Low level coronal emissions usually penetrate deep enough to completely mask this effect and show CH, quite similarly to the behaviour of the HeI lines (D3; 1083nm) which does not show the prolateness. We discuss the most recent observations for 1999 given by a new facility developped at Pic du Midi Observatory (HACO II) and we compare the results with EIT results in HeII. We also brielfly discuss the possible interpretations of the prolateness effect. We favor topological effects implying a large number of nano-flares and ejecta during the interactions of small-scale low level network magnetic fields with the more static large-scale magnetic field. Title: In-flight characterization and compensation of the optical properties of the EIT instrument Authors: Defise, Jean-Marc; Clette, Frederic; Auchere, Frederic Bibcode: 1999SPIE.3765..341D Altcode: Onboard the SOHO spacecraft, the Extreme UV Imaging Telescope (EIT) is imagin successfully the EUV solar corona since January 96. EIT is a normal incidence telescope, segmented in 4 separate quadrants. Each of those quadrants reflects extreme UV (EUV) light in a narrow bandpass defined by multilayer coatings deposited on the mirrors and by aluminum filters used to reject the visible and IR part of the solar irradiance. The specific configuration of the optical system is generating artifacts that must be compensated in the raw solar images. However, the only information available to improve image quality comes from the continuous survey of the solar corona accomplished in flight by EIT. In-flight image characteristics and instrumental aspects are discussed in this paper, showing how methods can be derived to clean up the EIT data. The current investigations are addressing the internal vignetting, the shadow pattern of grids supporting the focal filters, the determination of the instrumental point spread function and the assessment of the telescope focusing, as well as the relation between those factors. Title: SwRI/LASP sounding rocket inter-calibration with SOHO/EIT. Authors: Hassler, D. M.; Auchere, F.; Slater, D.; Woods, T. N. Bibcode: 1999BAAS...31.1241H Altcode: No abstract at ADS Title: SwRI/LASP Sounding Rocket Inter-calibration with SOHO/EIT Authors: Hassler, D. M.; Auchere, F.; Slater, D.; Woods, T. N. Bibcode: 1999AAS...19410803H Altcode: Two successful sounding rocket flights were launched on May 15, 1997 and Nov. 2, 1998 with an objective of providing inter-calibration with several of the instruments on SOHO and TRACE. We will discuss here the results of this inter-calibration between the SwRI/LASP rocket imaging instruments and the Extreme Ultraviolet Imaging Telescope (EIT) on SOHO. The Multiple XUV Imager (MXUVI) sounding rocket instrument is a multi-layer mirror telescope equiped with a special internal occulter and light trap to provide full disk images of Fe IX/X 171 A and off-limb observations of He II 304 A. The SOHO/EIT instrument is also a full disk multi-layer imager with four channels, Fe IX/X 171 A, Fe XII 195 A, Fe XV 284 A and He II 304 A. By comparison with the EIT observations taken at the same time we can quantify the sensitivity degradation or "limb-burning" of the EIT detector and construct a "flat field", as well as measure the off-limb stray light characteristics of the EIT He II 304 A channel. We will also discuss the radiometric calibration transfer between the rocket instrument and EIT. Title: Equivalent focal length measurements Authors: Artzner, Guy E.; Auchere, Frederic; Delaboudiniere, Jean-Pierre; Hochedez, Jean-Francois E. Bibcode: 1999SPIE.3737...32A Altcode: Converting linear coordinates in the plane of the detector of an astronomical instrument to celestial coordinates involves in principle the equivalent focal length of the instrument. However, most methods in astrometry manage to reduce observations in a global manner without actually measuring a focal length. We point out a case for solar space observations where the long term stability of angular distance measurements is better than the ground calibration of the angular value of a pixel. We report and discuss this ground calibration. Title: The prolate solar chromosphere Authors: Auchere, F.; Boulade, S.; Koutchmy, S.; Smartt, R. N.; Delaboudiniere, J. P.; Georgakilas, A.; Gurman, J. B.; Artzner, G. E. Bibcode: 1998A&A...336L..57A Altcode: We present a comparative analysis of the chromospheric solar limb prolateness, using strictly simultaneous H_alpha ground-based observations and Heriptsize{II} space-based observations. The typical prolateness is found to be Delta D/D=5.5*E(-3) in Heriptsize{II} and 1.2*E(-3) in H_alpha . The first measurements in the 30.4 nm Heriptsize{II} line over a period of two years, as well as coronal data, are discussed to explore further the origin of the prolateness and its possible consequences. Title: The polar extension of the solar chromosphere Authors: Auchère, F.; Delaboudinière, J. P.; Koutchmy, S.; Boulade, S. Bibcode: 1998ESASP.421..245A Altcode: 1998sjcp.conf..245A No abstract at ADS