Author name code: harrison ADS astronomy entries on 2022-09-14 author:"Harrison, Richard A." ------------------------------------------------------------------------ Title: Micromagnetic Modes of Anisotropy of Magnetic Susceptibility in Natural Magnetite Particles Authors: Nikolaisen, Even S.; Fabian, Karl; Harrison, Richard; McEnroe, Suzanne A. Bibcode: 2022GeoRL..4999758N Altcode: Anisotropy of magnetic susceptibility (AMS) is commonly used to assess sedimentation, deformation, tectonics, rock fabric, and texture. Using focused-ion beam nanotomography, we develop a micromagnetic method to investigate the AMS of individual magnetite inclusions in silicates across the transition between single-domain (SD) to multidomain behavior. We calculate individual AMS tensors by modeling the magnetization response of a particle to weak applied fields in three orthogonal directions. The main AMS mode of elongated SD particles is not a homogeneous magnetization rotation, but focused alignment of spins at their edges and tips. In single-vortex particles, vortex displacement is the dominant AMS mode, which focuses the largest magnetization changes in a planar region containing the vortex core, and perpendicular to the direction of vortex motion. In multi-vortex structures a combined motion of all vortex centers can lead to high degrees of anisotropy when some motion patterns are energetically much easier to achieve than others. Title: Calcium-Aluminum-Rich Inclusion Paleomagnetism: A Theoretical Perspective Authors: Bai, X. -N.; Borlina, C. S.; Weiss, B. P.; Mansbach, E. N.; Chatterjee, N.; Tung, P.; Harrison, R.; Lima, E. A.; Tissot, F. L. H.; McKeegan, K. D. Bibcode: 2022LPICo2678.2000B Altcode: We theoretically estimate the paleomagnetic field recorded by the CAIs following FUor-like outbursts to be 30-300 µT, well agreeing with recent measurements. Title: Paleomagnetism of Calcium-Aluminum-Rich Inclusions Authors: Borlina, C. S.; Weiss, B. P.; Bai, X.; Mansbach, E. N.; Chatterjee, N.; Tung, P.; Harrison, R.; Lima, E. A.; Tissot, F. L. H.; McKeegan, K. D. Bibcode: 2022LPICo2678.1913B Altcode: The paleomagnetism of calcium-aluminum-rich inclusions suggest they acquired their magnetization beyond 8 AU due to magnetized disk winds or stellar outbursts. Title: Comparing the Heliospheric Cataloging, Analysis, and Techniques Service (HELCATS) Manual and Automatic Catalogues of Coronal Mass Ejections Using Solar Terrestrial Relations Observatory/Heliospheric Imager (STEREO/HI) Data Authors: Rodriguez, L.; Barnes, D.; Hosteaux, S.; Davies, J. A.; Willems, S.; Pant, V.; Harrison, R. A.; Berghmans, D.; Bothmer, V.; Eastwood, J. P.; Gallagher, P. T.; Kilpua, E. K. J.; Magdalenic, J.; Mierla, M.; Möstl, C.; Rouillard, A. P.; Odstrčil, D.; Poedts, S. Bibcode: 2022SoPh..297...23R Altcode: We present the results of a comparative study between automatic and manually compiled coronal mass ejection (CME) catalogues based on observations from the Heliospheric Imagers (HIs) onboard NASA's Solar Terrestrial Relations Observatory (STEREO) spacecraft. Using the Computer Aided CME Tracking software(CACTus), CMEs are identified in HI data using an automatic feature-detection algorithm, while the Heliospheric Imagers Catalogue(HICAT) includes CMEs that are detected by visual inspection of HI images. Both catalogues were compiled as part of the EU FP7 Heliospheric Cataloguing, Analysis and Techniques Service (HELCATS) project (www.helcats-fp7.eu). We compare observational parameters of the CMEs from CACTus to those listed in HICAT, such as CME frequency, position angle (PA), and PA-width. We also compare CACTus-derived speeds to speeds derived from applying geometric modelling to the majority of the HICAT CMEs, the results of which are listed in the HELCATS Heliospheric Imagers Geometric Catalogue(HIGeoCAT). We find that both CACTus and HICAT catalogues contain a similar number of events when we exclude events narrower than 20, which are not included in the HICAT catalogue but are found to be identified by CACTus. PA-distributions are strongly peaked around 90 and 270, with a slightly larger CME frequency northwards of the equatorial plane (particularly for the STEREO-A versions of both catalogues). The CME PA-widths in both HICAT and CACTus catalogues peak at approximately 60. Manually derived speeds from HIGeoCAT and automatically derived speeds by CACTus correlate well for values lower than 1000 km s−1, in particular when CMEs are propagating close to the plane of the sky. Title: Multipoint Interplanetary Coronal Mass Ejections Observed with Solar Orbiter, BepiColombo, Parker Solar Probe, Wind, and STEREO-A Authors: Möstl, Christian; Weiss, Andreas J.; Reiss, Martin A.; Amerstorfer, Tanja; Bailey, Rachel L.; Hinterreiter, Jürgen; Bauer, Maike; Barnes, David; Davies, Jackie A.; Harrison, Richard A.; Freiherr von Forstner, Johan L.; Davies, Emma E.; Heyner, Daniel; Horbury, Tim; Bale, Stuart D. Bibcode: 2022ApJ...924L...6M Altcode: 2021arXiv210907200M We report the result of the first search for multipoint in situ and imaging observations of interplanetary coronal mass ejections (ICMEs) starting with the first Solar Orbiter (SolO) data in 2020 April-2021 April. A data exploration analysis is performed including visualizations of the magnetic-field and plasma observations made by the five spacecraft SolO, BepiColombo, Parker Solar Probe (PSP), Wind, and STEREO-A, in connection with coronagraph and heliospheric imaging observations from STEREO-A/SECCHI and SOHO/LASCO. We identify ICME events that could be unambiguously followed with the STEREO-A heliospheric imagers during their interplanetary propagation to their impact at the aforementioned spacecraft and look for events where the same ICME is seen in situ by widely separated spacecraft. We highlight two events: (1) a small streamer blowout CME on 2020 June 23 observed with a triple lineup by PSP, BepiColombo and Wind, guided by imaging with STEREO-A, and (2) the first fast CME of solar cycle 25 (≍1600 km s-1) on 2020 November 29 observed in situ by PSP and STEREO-A. These results are useful for modeling the magnetic structure of ICMEs and the interplanetary evolution and global shape of their flux ropes and shocks, and for studying the propagation of solar energetic particles. The combined data from these missions are already turning out to be a treasure trove for space-weather research and are expected to become even more valuable with an increasing number of ICME events expected during the rise and maximum of solar cycle 25. Title: Exploring the dynamics of inward core solidification using analogue tank experiments. Authors: Dodds, Kathryn; Bryson, James; Neufeld, Jerome; Harrison, Richard Bibcode: 2021AGUFMDI34B..05D Altcode: Given their small sizes and low central pressures, the cores of asteroids are expected to have started crystallizing at the core mantle boundary (CMB) instead of at their centre like the Earth. This behaviour is also predicted for Ganymede and has prompted the development of the iron snow model to explain its observed dynamo field, in which iron crystals that grow at the CMB in a snow zone and subsequently sink into the hotter interior and melt, releasing dense fluid that drives convection. However, whether this process could have occurred in asteroidal cores is uncertain due to the small adiabatic temperature difference between the CMB and the centre of their cores. Instead, the power for this compositional dynamo may have come from an increase in convective velocities caused by the addition of dense crystals at the CMB or turbulence caused by the settling of the crystals themselves. In this study we use analogue tank experiments to explore the possible dynamo driving mechanisms during inward asteroid core crystallisation. Ammonium chloride solution is cooled from above with a layer of buoyant propanol separating the solution from the cold plate to prevent the growth of crystals on this boundary. For a given temperature difference across this layer, we compare the convective velocities with and without crystallization to quantify the effect of the additional buoyancy flux on the fluid flow and to develop a scaling law that we implement in our thermal models of asteroid evolution. Previous models have suggested that the CMB heat flux could be sub- or super-adiabatic at the start of core crystallization, depending on the core size and its sulfur content, which we account for by varying the driving temperature difference in the tank. A complete upcoming dataset will allow us to quantify the mechanisms by which inward core solidification could generate a dynamo field. We also record the temperature and composition as a function of depth in the tank, enabling us to determine whether thermal equilibrium is maintained. This allows us to assess whether thermal equilibrium can be assumed when modelling snow zones in cores, a problem that is also relevant to larger planetary bodies cores (e.g. Ganymede, Mars, the Moon, the early Earth). Initial results suggest that thermal equilibrium is maintained, validating this key assumption. Title: In situ multi-spacecraft and remote imaging observations of the first CME detected by Solar Orbiter and BepiColombo Authors: Davies, E. E.; Möstl, C.; Owens, M. J.; Weiss, A. J.; Amerstorfer, T.; Hinterreiter, J.; Bauer, M.; Bailey, R. L.; Reiss, M. A.; Forsyth, R. J.; Horbury, T. S.; O'Brien, H.; Evans, V.; Angelini, V.; Heyner, D.; Richter, I.; Auster, H. -U.; Magnes, W.; Baumjohann, W.; Fischer, D.; Barnes, D.; Davies, J. A.; Harrison, R. A. Bibcode: 2021A&A...656A...2D Altcode: 2020arXiv201207456D Context. On 2020 April 19 a coronal mass ejection (CME) was detected in situ by Solar Orbiter at a heliocentric distance of about 0.8 AU. The CME was later observed in situ on April 20 by the Wind and BepiColombo spacecraft whilst BepiColombo was located very close to Earth. This CME presents a good opportunity for a triple radial alignment study, as the spacecraft were separated by less than 5° in longitude. The source of the CME, which was launched on April 15, was an almost entirely isolated streamer blowout. The Solar Terrestrial Relations Observatory (STEREO)-A spacecraft observed the event remotely from −75.1° longitude, which is an exceptionally well suited viewpoint for heliospheric imaging of an Earth directed CME.
Aims: The configuration of the four spacecraft has provided an exceptionally clean link between remote imaging and in situ observations of the CME. We have used the in situ observations of the CME at Solar Orbiter, Wind, and BepiColombo and the remote observations of the CME at STEREO-A to determine the global shape of the CME and its evolution as it propagated through the inner heliosphere.
Methods: We used three magnetic flux rope models that are based on different assumptions about the flux rope morphology to interpret the large-scale structure of the interplanetary CME (ICME). The 3DCORE model assumes an elliptical cross-section with a fixed aspect-ratio calculated by using the STEREO Heliospheric Imager (HI) observations as a constraint. The other two models are variants of the kinematically-distorted flux rope (KFR) technique, where two flux rope cross-sections are considered: one in a uniform solar wind and another in a solar-minimum-like structured solar wind. Analysis of CME evolution has been complemented by the use of (1) the ELEvoHI model to compare predicted CME arrival times and confirm the connection between the imaging and in situ observations, and (2) the PREDSTORM model, which provides an estimate of the Dst index at Earth using Solar Orbiter magnetometer data as if it were a real-time upstream solar wind monitor.
Results: A clear flattening of the CME cross-section has been observed by STEREO-A, and further confirmed by comparing profiles of the flux rope models to the in situ data, where the distorted flux rope cross-section qualitatively agrees most with in situ observations of the magnetic field at Solar Orbiter. Comparing in situ observations of the magnetic field between spacecraft, we find that the dependence of the maximum (mean) magnetic field strength decreases with heliocentric distance as r−1.24 ± 0.50 (r−1.12 ± 0.14), which is in disagreement with previous studies. Further assessment of the axial and poloidal magnetic field strength dependencies suggests that the expansion of the CME is likely neither self-similar nor cylindrically symmetric. Title: Multipoint ICME events during the first 1.5 years of combined Solar Orbiter, BepiColombo, Parker Solar Probe, Wind and STEREO-A observations Authors: Moestl, Christian; Weiss, Andreas; Reiss, Martin; Bailey, Rachel; Amerstorfer, Tanja; Hinterreiter, Jurgen; Bauer, Maike; Barnes, David; Harrison, Richard; Davies, Jackie; Heyner, Daniel Bibcode: 2021AGUFMSH15A2027M Altcode: We show in multipoint situ observations of interplanetary coronal mass ejections (ICMEs) starting with Solar Orbiter operations in April 2020. We demonstrate visualizations of the magnetic field and plasma observations by the 5 spacecraft Solar Orbiter, BepiColombo, Parker Solar Probe, Wind and STEREO-A, in connection with heliospheric imager observations from STEREO-A. We identify ICME events that (1) could be unambiguously followed from their inception on the Sun to their impact at the aforementioned spacecraft, and (2) highlight much sought-after lineup events, which are useful for many different research efforts, e.g. the modeling of ICME flux ropes, their interplanetary evolution and the studies of solar energetic particle events. We catalog all these ICME events for the community at https://www.helioforecast.space/icmecat. The combined data of these missions is already turning out to be a treasure trove for space weather research and is expected to become even more valuable with a increasing number of events expected during the rise of solar cycle 25. Title: Predicting CMEs Using ELEvoHI With STEREO-HI Beacon Data Authors: Bauer, Maike; Amerstorfer, Tanja; Hinterreiter, Jürgen; Weiss, Andreas J.; Davies, Jackie A.; Möstl, Christian; Amerstorfer, Ute V.; Reiss, Martin A.; Harrison, Richard A. Bibcode: 2021SpWea..1902873B Altcode: 2021arXiv210808072B Being able to accurately predict the arrival of coronal mass ejections (CMEs) at Earth has been a long-standing problem in space weather research and operations. In this study, we use the ELlipse Evolution model based on Heliospheric Imager (ELEvoHI) to predict the arrival time and speed of 10 CME events that were observed by HI on the STEREO-A spacecraft between 2010 and 2020. Additionally, we introduce a Python tool for downloading and preparing STEREO-HI data, as well as tracking CMEs. In contrast to most previous studies, we use not only science data, which have a relatively high spatial and temporal resolution, but also lower-quality beacon data, which are—in contrast to science data—provided in real-time by the STEREO-A spacecraft. We do not use data from the STEREO-B spacecraft. We get a mean absolute error of 8.81 ± 3.18 hr/59 ± 31 km s-1 for arrival time/speed predictions using science data and 11.36 ± 8.69 hr/106 ± 61 km s-1 for beacon data. We find that using science data generally leads to more accurate predictions, but using beacon data with the ELEvoHI model is certainly a viable choice in the absence of higher resolution real-time data. We propose that these differences could be minimized if not eliminated altogether if higher quality real-time data were available, either by enhancing the quality of the already available data or coming from a new mission carrying a HI instrument on-board. Title: The early phase lunar magnetic field as recorded by Apollo 17 mare basalts Authors: Vervelidou, Foteini; Weiss, Benjamin; Nichols, Claire; Murray, Mary; Shah, Jay; Sheikh, Hassan; Harrison, Richard; Lagroix, France Bibcode: 2021AGUFMGP44A..05V Altcode: Lunar rocks provide evidence that the Moon once sustained a lunar core dynamo. Several studies have provided evidence that the lunar magnetic field during the period 4.25 to 3.56 Ga had a strength similar to that of the Earth nowadays. However, dynamo scaling laws suggest that the Moon lacks the energy budget required to sustain a convective dynamo that could generate such a strong magnetic field continuously throughout this period. This possible discrepancy has motivated the hypothesis that the lunar dynamo field was only intermittently strong during this time. To test this hypothesis, we have been conducting paleomagnetic, rock magnetic, and petrologic measurements on four 3.7 billion years old Apollo 17 mare basalts with textures ranging from coarse- to fine-grained. Using alternating field demagnetization and remagnetization experiments, we show that the recording properties of these samples exhibit a large variability, even on the millimeter-scale. In particular, we find that using the anhysteretic remanent magnetization paleointensity method, we can accurately retrieve paleointensities from thermoremanence acquired in minimum fields ranging from 7 to 75 T over the coercivity range 3-70 mT. According to our results thus far, all 10 subsamples that can record fields at least as low as 20 T have recorded magnetizations which correspond to paleointensities of several tens of T. Therefore, we have yet to confidently identify samples dating from the early phase of the lunar dynamo that recorded a low lunar paleofield. Title: Venus's induced magnetosphere during active solar wind conditions at BepiColombo's Venus 1 flyby Authors: Volwerk, Martin; Sánchez-Cano, Beatriz; Heyner, Daniel; Aizawa, Sae; André, Nicolas; Varsani, Ali; Mieth, Johannes; Orsini, Stefano; Baumjohann, Wolfgang; Fischer, David; Futaana, Yoshifumi; Harrison, Richard; Jeszenszky, Harald; Kazumasa, Iwai; Laky, Gunter; Lichtenegger, Herbert; Milillo, Anna; Miyoshi, Yoshizumi; Nakamura, Rumi; Plaschke, Ferdinand; Richter, Ingo; Rojas Mata, Sebastián; Saito, Yoshifumi; Schmid, Daniel; Shiota, Daikou; Wedlund, Cyril Simon Bibcode: 2021AnGeo..39..811V Altcode: Out of the two Venus flybys that BepiColombo uses as a gravity assist manoeuvre to finally arrive at Mercury, the first took place on 15 October 2020. After passing the bow shock, the spacecraft travelled along the induced magnetotail, crossing it mainly in the YVSO direction. In this paper, the BepiColombo Mercury Planetary Orbiter Magnetometer (MPO-MAG) data are discussed, with support from three other plasma instruments: the Planetary Ion Camera (SERENA-PICAM) of the SERENA suite, the Mercury Electron Analyser (MEA), and the BepiColombo Radiation Monitor (BERM). Behind the bow shock crossing, the magnetic field showed a draping pattern consistent with field lines connected to the interplanetary magnetic field wrapping around the planet. This flyby showed a highly active magnetotail, with e.g. strong flapping motions at a period of ∼7 min. This activity was driven by solar wind conditions. Just before this flyby, Venus's induced magnetosphere was impacted by a stealth coronal mass ejection, of which the trailing side was still interacting with it during the flyby. This flyby is a unique opportunity to study the full length and structure of the induced magnetotail of Venus, indicating that the tail was most likely still present at about 48 Venus radii. 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: A journey of exploration to the polar regions of a star: probing the solar poles and the heliosphere from high helio-latitude Authors: Harra, Louise; Andretta, Vincenzo; Appourchaux, Thierry; Baudin, Frédéric; Bellot-Rubio, Luis; Birch, Aaron C.; Boumier, Patrick; Cameron, Robert H.; Carlsson, Matts; Corbard, Thierry; Davies, Jackie; Fazakerley, Andrew; Fineschi, Silvano; Finsterle, Wolfgang; Gizon, Laurent; Harrison, Richard; Hassler, Donald M.; Leibacher, John; Liewer, Paulett; Macdonald, Malcolm; Maksimovic, Milan; Murphy, Neil; Naletto, Giampiero; Nigro, Giuseppina; Owen, Christopher; Martínez-Pillet, Valentín; Rochus, Pierre; Romoli, Marco; Sekii, Takashi; Spadaro, Daniele; Veronig, Astrid; Schmutz, W. Bibcode: 2021ExA...tmp...93H Altcode: 2021arXiv210410876H A mission to view the solar poles from high helio-latitudes (above 60°) will build on the experience of Solar Orbiter as well as a long heritage of successful solar missions and instrumentation (e.g. SOHO Domingo et al. (Solar Phys. 162(1-2), 1-37 1995), STEREO Howard et al. (Space Sci. Rev. 136(1-4), 67-115 2008), Hinode Kosugi et al. (Solar Phys. 243(1), 3-17 2007), Pesnell et al. Solar Phys. 275(1-2), 3-15 2012), but will focus for the first time on the solar poles, enabling scientific investigations that cannot be done by any other mission. One of the major mysteries of the Sun is the solar cycle. The activity cycle of the Sun drives the structure and behaviour of the heliosphere and of course, the driver of space weather. In addition, solar activity and variability provides fluctuating input into the Earth climate models, and these same physical processes are applicable to stellar systems hosting exoplanets. One of the main obstructions to understanding the solar cycle, and hence all solar activity, is our current lack of understanding of the polar regions. In this White Paper, submitted to the European Space Agency in response to the Voyage 2050 call, we describe a mission concept that aims to address this fundamental issue. In parallel, we recognise that viewing the Sun from above the polar regions enables further scientific advantages, beyond those related to the solar cycle, such as unique and powerful studies of coronal mass ejection processes, from a global perspective, and studies of coronal structure and activity in polar regions. Not only will these provide important scientific advances for fundamental stellar physics research, they will feed into our understanding of impacts on the Earth and other planets' space environment. Title: IPSCAT: A Catalogue of Solar Transients Identified through Interplanetary Scintillation Analysis Authors: Barnes, David; Bisi, Mario; Davies, Jackie; Harrison, Richard Bibcode: 2021EGUGA..23.2667B Altcode: We present a catalogue, IPSCAT, of the results of Interplanetary Scintillation (IPS) analysis applied to observations that are compiled using data from three European radio networks, EISCAT, MERLIN and LOFAR, during the early science phase of the STEREO mission, from 2007 to 2012. These analyses provide a means to study the solar wind and interplanetary transients, which we complement with observations from the Heliospheric Imagers on-board STEREO. Within the IPS data set we identify transient phenomena, specifically Coronal Mass Ejections (CMEs) and Stream Interaction Regions (SIRs), via both visual inspection and an automatic feature-finding algorithm. We study the effectiveness of the automated detection algorithm and find it to be successful at classifying CMEs, whilst the identification of SIRs is less easily established. A discussion of the statistical properties of IPSCAT is presented, together with a comparison between the IPS and HI results. Finally, we present a case study of successive CMEs within the IPSCAT data set, which were also observed by the HIs on both STEREO spacecraft and analysed using the Stereoscopic Self-Similar Expansion (SSSE) method. This work was carried out as part of the EU FP7 HELCATS (Heliospheric Cataloguing, Analysis and Techniques Service) project (http://www.helcats-fp7.eu/). Title: Effect of the ambient solar wind speed on drag-based CME prediction accuracy Authors: Amerstorfer, Tanja; Hinterreiter, Jürgen; Reiss, Martin A.; Davies, Jackie A.; Möstl, Christian; Weiss, Andreas J.; Bauer, Maike; Amerstorfer, Ute V.; Bailey, Rachel L.; Harrison, Richard A. Bibcode: 2021EGUGA..23.8932A Altcode: In the last years, many kinds of CME models, based on a drag-based evolution through interplanetary space, have been developed and are now widely used by the community. The unbeatable advantage of those methods is that they are computationally cheap and are therefore suitable to be used as ensemble models. Additionally, their prediction accuracy is absolutely comparable to more sophisticated models.The ELlipse Evolution model based on heliospheric imager (HI) observations (ELEvoHI) assumes an elliptic frontal shape within the ecliptic plane and allows the CME to adjust to the ambient solar wind speed, i.e. it is drag-based. ELEvoHI is used as an ensemble simulation by varying the CME frontal shape within given boundary values. The results include a frequency distribution of predicted arrival time and arrival speed and an estimation of the arrival probability.In this study, we investigate the possibility of not only varying the parameters related to the CME's ecliptic extent but also the ambient solar wind speed for each CME ensemle member. Although we have used a range of +/-100 km/s for possible values of the solar wind speed in the past, only the best candidate was in the end used to contribute to the prediction. We present the results of this approach by applying it to a CME propagating in a highly structured solar wind and compare the frequency distribution of the arrival time and speed predictions to those of the usual ELEvoHI approach. Title: Overview of interplanetary coronal mass ejections observed by Solar Orbiter, Parker Solar Probe, Bepi Colombo, Wind and STEREO-A Authors: Möstl, Christian; Weiss, Andreas J.; Bailey, Rachel L.; Reiss, Martin A.; Amerstorfer, Tanja; Hinterreiter, Jürgen; Bauer, Maike; Amerstorfer, Ute V.; Davies, Emma E.; Horbury, Tim; Barnes, David; Davies, Jackie A.; Harrison, Richard A.; Heyner, Daniel; Richter, Ingo; Auster, Hans-Ulrich; Magnes, Werner; Baumjohann, Wolfgang Bibcode: 2021EGUGA..23..592M Altcode: We show in situ observations of ICMEs during the first year of Solar Orbiter observations based on magnetic field data from the MAG instrument in conjunction with in situ and imaging observations from the Heliospheric System Observatory. The in situ magnetic field data from four other currently active spacecraft - Parker Solar Probe, BepiColombo, STEREO-Ahead and Wind - are also searched for ICME signatures, and all clear ICME events that could be identified by classic signatures such as elevated and rotating magnetic fields of sufficiently long durations are included in a living online catalog. Furthermore, we provide a visualization of the in situ magnetic field data alongside spacecraft positions and propagating CME fronts, which are based on modeling of STEREO-A heliospheric imager data. This allows us to identify ICME events that could be unambiguously followed from their inception on the Sun to their impact at the aforementioned spacecraft, and highlights sought-after lineup events, in which the same ICME is observed at multiple points in space, such as the well-studied 2020 April 15-20 ICME. We discuss the ICME rate observed so far, and provide an outlook on the expected ICME rate in solar cycle 25 based on different forecasts for the cycle amplitude (see Möstl et al. 2020, https://doi.org/10.3847/1538-4357/abb9a1). Title: Space Weather Awareness, Engagement, and Outreach Activities at UKRI STFC RAL Space Authors: Bisi, Mario M.; Hapgood, Mike; Harrison, Richard Bibcode: 2021cosp...43E2432B Altcode: Space weather is a natural hazard posing a threat to critical infrastructures worldwide with varying global and regional impacts. Phenomena such as geomagnetic storms and atmospheric disturbances can impact power grids, communications, and various other satellite signals. The risk has increased in prominence as society has become more dependent on space-based technologies and on more-modern infrastructures susceptible to space-weather impacts. Space weather originates at the Sun, and so it is important to understand the Sun-Earth chain of events to be able to forecast and mitigate for such space-weather phenomena and to predict their effects and resulting impacts on human society. Following the inclusion of severe space weather in the National Risk Register of Civil Emergencies in 2011, STFC led a Public Dialogue exercise on space weather which brought experts and the general public together to discuss the space weather and establish the general awareness of space weather from across different locations in the UK. The report of this project provided insights on how best to establish policies that will engage the general public in the mitigation of problems caused by space weather. In the same timeframe, STFC also led a three-year academic networking activity (named SEREN) that funded activities to give scientists better insight into the types of information that industry and policy-makers need in order to address the problems caused by space weather. More widely, the UK has undertaken a series of wide-ranging investigations to mitigate space-weather impacts at the national level including the ongoing development of a national Space Weather Strategy - where the UK looks to experts across all sectors to feed into its development. This has also previously included the setting up of a UK staffed 24/7 space-weather forecasting centre at the Met Office alongside the formation of the Space Environment Impacts Expert Group (SEIEG) of space-weather experts to provide the necessary advice to government; this latter group is currently Chaired from RAL Space. In this presentation, we will provide an overview of the above with an emphasis on the key activities past, present, and planned, at RAL Space around space weather awareness, engagement, and outreach. 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: Evaluation of CME Arrival Prediction Using Ensemble Modeling Based on Heliospheric Imaging Observations Authors: Amerstorfer, Tanja; Hinterreiter, Jürgen; Reiss, Martin A.; Möstl, Christian; Davies, Jackie A.; Bailey, Rachel L.; Weiss, Andreas J.; Dumbović, Mateja; Bauer, Maike; Amerstorfer, Ute V.; Harrison, Richard A. Bibcode: 2021SpWea..1902553A Altcode: 2020arXiv200802576A In this study, we evaluate a coronal mass ejection (CME) arrival prediction tool that utilizes the wide-angle observations made by STEREO's heliospheric imagers (HI). The unsurpassable advantage of these imagers is the possibility to observe the evolution and propagation of a CME from close to the Sun out to 1 AU and beyond. We believe that by exploiting this capability, instead of relying on coronagraph observations only, it is possible to improve today's CME arrival time predictions. The ELlipse Evolution model based on HI observations (ELEvoHI) assumes that the CME frontal shape within the ecliptic plane is an ellipse and allows the CME to adjust to the ambient solar wind speed; that is, it is drag based. ELEvoHI is used to perform ensemble simulations by varying the CME frontal shape within given boundary conditions that are consistent with the observations made by HI. In this work, we evaluate different setups of the model by performing hindcasts for 15 well-defined isolated CMEs that occurred when STEREO was near L4/5, between the end of 2008 and the beginning of 2011. In this way, we find a mean absolute error of between 6.2 ± 7.9 and 9.9 ± 13 hr depending on the model setup used. ELEvoHI is specified for using data from future space weather missions carrying HIs located at L5 or L1. It can also be used with near-real-time STEREO-A HI beacon data to provide CME arrival predictions during the next ∼7 years when STEREO-A is observing the Sun-Earth space. Title: A Journey of Exploration to the Polar Regions of a Star: Probing the Solar Poles and the Heliosphere from High Helio-Latitude Authors: Finsterle, W.; Harra, L.; Andretta, V.; Appourchaux, T.; Baudin, F.; Bellot Rubio, L.; Birch, A.; Boumier, P.; Cameron, R. H.; Carlsson, M.; Corbard, T.; Davies, J. A.; Fazakerley, A. N.; Fineschi, S.; Gizon, L. C.; Harrison, R. A.; Hassler, D.; Leibacher, J. W.; Liewer, P. C.; Macdonald, M.; Maksimovic, M.; Murphy, N.; Naletto, G.; Nigro, G.; Owen, C. J.; Martinez-Pillet, V.; Rochus, P. L.; Romoli, M.; Sekii, T.; Spadaro, D.; Veronig, A. Bibcode: 2020AGUFMSH0110005F Altcode: A mission to view the solar poles from high helio-latitudes (above 60°) will build on the experience of Solar Orbiter as well as a long heritage of successful solar missions and instrumentation (e.g. SOHO, STEREO, Hinode, SDO), but will focus for the first time on the solar poles, enabling scientific investigations that cannot be done by any other mission. One of the major mysteries of the Sun is the solar cycle. The activity cycle of the Sun drives the structure and behaviour of the heliosphere and is, of course, the driver of space weather. In addition, solar activity and variability provides fluctuating input into the Earth climate models, and these same physical processes are applicable to stellar systems hosting exoplanets. One of the main obstructions to understanding the solar cycle, and hence all solar activity, is our current lack of understanding of the polar regions. We describe a mission concept that aims to address this fundamental issue. In parallel, we recognise that viewing the Sun from above the polar regions enables further scientific advantages, beyond those related to the solar cycle, such as unique and powerful studies of coronal mass ejection processes, from a global perspective, and studies of coronal structure and activity in polar regions. Not only will these provide important scientific advances for fundamental stellar physics research, they will feed into our understanding of impacts on the Earth and other planets' space environment. Title: IPSCAT: A Catalogue of Solar Transients Identified through Interplanetary Scintillation Analysis Authors: Barnes, D.; Bisi, M. M.; Davies, J. A.; Harrison, R. A. Bibcode: 2020AGUFMSH0440024B Altcode: We present a catalogue, IPSCAT, of the results of Interplanetary Scintillation (IPS) analysis applied to observations that are compiled using data from three European radio networks, EISCAT, MERLIN and LOFAR, during the early science phase of the STEREO mission, from 2007 to 2012. These analyses provide a means to study the solar wind and interplanetary transients, which we complement with observations from the Heliospheric Imagers on-board STEREO. Within the IPS data set we identify transient phenomena, specifically Coronal Mass Ejections (CMEs) and Stream Interaction Regions (SIRs), via both visual inspection and an automatic feature-finding algorithm. We study the effectiveness of the automated detection algorithm and find it to be successful at classifying CMEs, whilst the identification of SIRs is less easily established. A discussion of the statistical properties of IPSCAT is presented, together with a comparison between the IPS and HI results. Finally, we present a case study of successive CMEs within the IPSCAT data set, which were also observed by the HIs on both STEREO spacecraft and analysed using the Stereoscopic Self-Similar Expansion (SSSE) method. Title: CMEs in the Heliosphere: III. A Statistical Analysis of the Kinematic Properties Derived from Stereoscopic Geometrical Modelling Techniques Applied to CMEs Detected in the Heliosphere from 2008 to 2014 by STEREO/HI-1 Authors: Barnes, D.; Davies, J. A.; Harrison, R. A.; Byrne, J. P.; Perry, C. H.; Bothmer, V.; Eastwood, J. P.; Gallagher, P. T.; Kilpua, E. K. J.; Möstl, C.; Rodriguez, L.; Rouillard, A. P.; Odstrčil, D. Bibcode: 2020SoPh..295..150B Altcode: 2020arXiv200614879B We present an analysis of coronal mass ejections (CMEs) observed by the Heliospheric Imagers (HIs) onboard NASA's Solar Terrestrial Relations Observatory (STEREO) spacecraft. Between August 2008 and April 2014 we identify 273 CMEs that are observed simultaneously, by the HIs on both spacecraft. For each CME, we track the observed leading edge, as a function of time, from both vantage points, and apply the Stereoscopic Self-Similar Expansion (SSSE) technique to infer their propagation throughout the inner heliosphere. The technique is unable to accurately locate CMEs when their observed leading edge passes between the spacecraft; however, we are able to successfully apply the technique to 151, most of which occur once the spacecraft-separation angle exceeds 180, during solar maximum. We find that using a small half-width to fit the CME can result in inferred acceleration to unphysically high velocities and that using a larger half-width can fail to accurately locate the CMEs close to the Sun because the method does not account for CME over-expansion in this region. Observed velocities from SSSE are found to agree well with single-spacecraft (SSEF) analysis techniques applied to the same events. CME propagation directions derived from SSSE and SSEF analysis agree poorly because of known limitations present in the latter. 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 High Helium Abundance and Charge States of the Interplanetary CME and Its Material Source on the Sun Authors: Fu, Hui; Harrison, R. A.; Davies, J. A.; Xia, LiDong; Zhu, XiaoShuai; Li, Bo; Huang, ZhengHua; Barnes, D. Bibcode: 2020ApJ...900L..18F Altcode: 2020arXiv200808816F Identifying the source of the material within coronal mass ejections (CMEs) and understanding CME onset mechanisms are fundamental issues in solar and space physics. Parameters relating to plasma composition, such as charge states and He abundance (AHe), may be different for plasmas originating from differing processes or regions on the Sun. Thus, it is crucial to examine the relationship between in situ measurements of CME composition and activity on the Sun. We study the CME that erupted on 2014 September 10, in association with an X1.6 flare, by analyzing Atmospheric Imaging Assembly imaging and Interface Region Imaging Spectrograph (IRIS) spectroscopic observations and its in situ signatures detected by Wind and Advanced Composition Explorer. We find that during the slow expansion and intensity increase of the sigmoid, plasma temperatures of 9 MK, and higher, first appear at the footpoints of the sigmoid, associated with chromospheric brightening. Then the high-temperature region extends along the sigmoid. IRIS observations confirm that this extension is caused by transportation of hot plasma upflow. Our results show that chromospheric material can be heated to 9 MK, and above, by chromospheric evaporation at the sigmoid footpoints before flare onset. The heated chromospheric material can transport into the sigmoidal structure and supply mass to the CME. The aforementioned CME mass supply scenario provides a reasonable explanation for the detection of high charge states and elevated AHe in the associated interplanetary CME. The observations also demonstrate that the quasi-steady evolution in the precursor phase is dominated by magnetic reconnection between the rising flux rope and the overlying magnetic field structure. Title: A comprehensive catalogue of solar wind properties and events in the inner heliosphere Authors: Bailey, Rachel; Reiss, Martin; Möstl, Christian; Amerstorfer, Ute; Wedlund, Cyril Simon; Amerstorfer, Tanja; Weiss, Andreas; Hinterreiter, Jürgen; Guo, Jingnan; von Forstner, Johan; Barnes, David; Davies, Jackie; Harrison, Richard Bibcode: 2020EPSC...14..562B Altcode: The evolving ambient solar wind is one of the key links between the Sun and planetary bodies in our solar system. Here we present a comprehensive catalogue of solar wind properties, stream interaction regions, and coronal mass ejections at different locations in the inner heliosphere. Our database incorporates observational data products and also solar wind modelling results. The solar wind modelling is based on two different approaches for modelling the conditions in the ambient solar wind. While the WSA/THUX model combination solves the viscous form of the underlying Burgers equation to compute the two-dimensional solar wind conditions in our solar system, the second approach is a computationally fast machine learning method for predicting the ambient solar wind flows at Earth. Statistics of the ambient solar wind model results for more than 15 years in combination with a catalogue of coronal mass ejections observed at the Earth, Mars and STEREO satellites along with stream interaction regions provide a comprehensive overview of the past and present solar wind behaviour for shaping planetary space weather. Title: A Catalogue of Coronal Mass Ejections Observed by the Heliospheric Imagers throughout the STEREO Mission Authors: Barnes, David; Davies, Jackie; Harrison, Richard Bibcode: 2020EGUGA..2216546B Altcode: Understanding the evolution of the solar wind is fundamental to advancing our knowledge of energy and mass transport in the solar system, rendering it crucial to space weather and its prediction. The advent of truly wide-angle heliospheric imaging has revolutionised the study of Coronal Mass Ejections (CMEs) by enabling their direct and continuous observation out to 1 AU and beyond. A catalogue of CMEs has been compiled using data from the Heliospheric Imagers (HIs) on board the two STEREO spacecraft, which began as part of the FP7 HELCATS project. The mission was launched in 2006 and continues to provide data, therefore spanning 13 years, over which more than two-thousand CMEs have been observed using HI. To these CMEs, we apply geometric models that make use of both single-spacecraft and stereoscopic observations in order to determine their kinematic properties. These include CME speed, acceleration, propagation direction and launch time. The resulting kinematic properties and their statistics are discussed in the context of existing CME catalogues produced from coronagraph observations. This is done with emphasis on how the different models we apply influence our results and how these differences evolve over the solar cycle and as the angular separation of the STEREO spacecraft increases throughout the mission. Title: CME arrival prediction and its dependency on input data and model parameters Authors: Amerstorfer, Tanja; Hinterreiter, Jürgen; Reiss, Martin A.; Bauer, Maike; Möstl, Christian; Bailey, Rachel L.; Weiss, Andreas J.; Amerstorfer, Ute V.; Davies, Jackie A.; Harrison, Richard Bibcode: 2020EGUGA..22.4703A Altcode: During the last years, we focused on developing a prediction tool that utilizes the wide-angle observations of STEREO's heliospheric imagers. The unsurpassable advantage of these imagers is the possibility to observe the evolution and propagation of a coronal mass ejection (CME) from close to the Sun up to 1 AU and beyond. We believe that using this advantage instead of relying on coronagraph observations that are limited to observe only 14% of the Sun-Earth line, it is possible to improve today's CME arrival time predictions.The ELlipse Evolution model based on HI observations (ELEvoHI) assumes an elliptic frontal shape within the ecliptic plane and allows the CME to adjust to the ambient solar wind speed, i.e. it is drag-based. ELEvoHI is used as an ensemble simulation by varying the CME frontal shape within given boundary values. The results include a frequency distrubution of predicted arrival time and arrival speed and an estimation of the arrival probability. ELEvoHI can be operated using several kinds of inputs. In this study we investigate 15 well-defined single CMEs when STEREO was around L4/5 between the end of 2009 and the beginning of 2011. Three different sources of input propagation directions (and shapes) are used together with three different sources of ambient solar wind speed and two different ways of defining the most appropriate fit to the HI data. The combination of these different approaches and inputs leads to 18 different model set-ups used to predict each of the 15 events in our list leading to 270 ELEvoHI ensemble predictions and all in all to almost 60000 runs. To identify the most suitable and most accurate model set-up to run ELEvoHI, we compare the predictions to the actual in situ arrival of the CMEs.This model is specified for using data from future space weather missions carrying HIs located at L5 or L1 and can also directly be used together with STEREO-A near real-time HI beacon data to provide real-time CME arrival predictions during the next 7 years when STEREO-A is observing the Sun-Earth space. Title: From heliophysics to space weather forecasts Authors: Harrison, Richard; Davies, Jackie; Rae, Jonny Bibcode: 2019A&G....60e5.26H Altcode: Richard Harrison, Jackie Davies and Jonny Rae summarize progress in capitalizing on UK expertise in research and instrumentation for new space weather forecasting - the subject of an RAS Discussion Meeting in March. Title: CMEs in the Heliosphere: II. A Statistical Analysis of the Kinematic Properties Derived from Single-Spacecraft Geometrical Modelling Techniques Applied to CMEs Detected in the Heliosphere from 2007 to 2017 by STEREO/HI-1 Authors: Barnes, D.; Davies, J. A.; Harrison, R. A.; Byrne, J. P.; Perry, C. H.; Bothmer, V.; Eastwood, J. P.; Gallagher, P. T.; Kilpua, E. K. J.; Möstl, C.; Rodriguez, L.; Rouillard, A. P.; Odstrčil, D. Bibcode: 2019SoPh..294...57B Altcode: Recent observations with the Heliospheric Imagers (HIs) onboard the twin NASA Solar Terrestrial Relations Observatory (STEREO) spacecraft have provided unprecedented observations of a large number of coronal mass ejections (CMEs) in the inner heliosphere. In this article we discuss the generation of the HIGeoCAT CME catalogue and perform a statistical analysis of its events. The catalogue was generated as part of the EU FP7 HELCATS (Heliospheric Cataloguing, Analysis and Techniques Service) project (www.helcats-fp7.eu/). It is created by generating time/elongation maps for CMEs using observations from the inner (HI-1) and outer (HI-2) cameras along a position angle close to the CME apex. Next, we apply single-spacecraft geometric-fitting techniques to determine the kinematic properties of these CMEs, including their speeds, propagation directions, and launch times. The catalogue contains a total of 1455 events (801 from STEREO-A and 654 from STEREO-B) from April 2007 to the end of August 2017. We perform a statistical analysis of the properties of CMEs in HIGeoCAT and compare the results with those from the Large Angle Spectrometric Coronagraph (LASCO) CDAW catalogues (Yashiro et al.J. Geophys. Res. Space Phys.109, A07105, 2004) and the COR-2 catalogue of Vourlidas et al. (Astrophys. J.838, 141, 2004) during the same period. We find that the distributions of both speeds and latitudes for the HIGeoCAT CMEs correlate with the sunspot number over the solar cycle. We also find that the HI-derived CME speed distributions are generally consistent with coronagraph catalogues over the solar cycle, albeit with greater absolute speeds due to the differing methods with which each is derived. Title: Nanopaleomagnetism: How to extract and understand ancient extraterrestrial magnetic signals from meteorites using synchrotron X-rays Authors: Nichols, Claire; Bryson, James; Herrero-Albillos, Julia; Kronast, Florian; Im, Mi-Young; Harrison, Richard Bibcode: 2019EGUGA..21.3685N Altcode: Magnetic signals recorded by meteorites provide invaluable information about the formation and evolution of our solar system. Before interpreting these signals, it is essential to understand how these signals are being recorded, and whether they are likely to be stable for billions of years. Over the last five years significant progress has been made in understanding the magnetic information recorded by iron-bearing meteorites. The bulk of meteoritic metal is kamacite (Fe0.95Ni0.05) which forms large mm-scale lamellae in the Widmanstätten pattern, a characteristic feature of slow-cooled iron meteorites. These kamacite lamellae are magnetically soft; they are multidomain and any magnetic information recorded is easily overwritten. Between the large-scale kamacite lamellae however, a range of microstructures form, including the cloudy zone. The cloudy zone consists of nanoscale islands of tetrataenite (Fe0.5Ni0.5) in an Fe-rich matrix. These tetrataenite islands are exceptional paleomagnetic recorders but their small size makes extracting paleomagnetic information experimentally challenging. X-ray photoemission electron microscopy (X-PEEM) allows the distribution of magnetization within the cloudy zone to be imaged with nanoscale resolution. This technique has been used to characterize the magnetic behavior of numerous meteoritic FeNi microstructures and has also been used to calculate paleointensities generated by planetesimal dynamos within the first 200 million years of solar system formation. Examples of studies on the IAB iron meteorites, the Main Group pallasites and the mesosiderites will be discussed. Paleomagnetic signals have also been extracted from chondritic meteorites, which contain the first solids to have formed in our solar system. Paleomagnetic signals recorded by nanoscale Fe particles in dusty olivine grains in the Semarkona LL3.0 chondrite are interpreted as evidence for the strength of the solar nebula magnetic field. This record has significant implications for the evolution of the protoplanetary disk. Numerous microscopy studies have been conducted to verify the ability of these Fe particles to record stable paleomagnetic records from the earliest history of the solar system. Magnetic transmission X-ray microscopy (MTXM) has been used to image the nanoscale magnetic structure within individual Fe-particles from the Semarkona LL3.0 chondrite under applied laboratory fields and they are found to be stable in magnetic fields of at least 200 mT. MTXM has a significant advantage over electron microscopy techniques since imaging can be conducted under applied magnetic fields. This is very difficult to achieve using techniques such as Lorentz microscopy or electron holography as the applied magnetic field causes the electron beam to be deflected, defocusing the image. Title: Importance of heliospheric imager track quality for CME arrival prediction accuracy Authors: Amerstorfer, Tanja; Hinterreiter, Jürgen; Möstl, Christian; Davies, Jackie A.; Amerstorfer, Ute V.; Reiss, Martin A.; Temmer, Manuela; Bailey, Rachel L.; Harrison, Richard A. Bibcode: 2019EGUGA..21.7373A Altcode: Operational CME arrival prediction is mainly conducted using magnetohydrodynamic models based on coronagraph observations and magnetograms. Although the Solar TErrestrial RElations Observatory with its heliospheric imagers (HI) provides the possibility to trace a CME's propagation along its path from the Sun to 1 AU, these data can hardly be used to predict CME arrivals in real time (except for a few events in an early phase of the mission). One of the main reasons for that is a large number of data gaps in beacon data, which is available in near real time (in contrast to the complete science data), impeding a proper measurement of the CME front. With regard to a possible future L5 mission carrying HIs we investigate the most suitable way of extracting the time-elongation track of CMEs from HI observations leading to a prediction with the highest possible accuracy. As a first step to reach this goal, we use time-elongation tracks measured from STEREO/HI science data and provided by the FP7 HELCATS team as well as tracks derived using time-elongation maps and tracks measured directly in an HI image time series. These time-elongation tracks are further used as input to our CME ensemble prediction tool ELEvoHI (ELlipse Evolution model based on HI data), which assumes a drag-based interplanetary CME propagation and an elliptical CME frontal shape. ELEvoHI produces post-event predictions of arrival times and speeds at 1 AU for all tracks of each CME under study. By comparing the prediction results from several ways of tracking we attempt to deduce a preferable approach for future studies, e.g. when using data from Parker Solar Probe's Wide-Field Imager for Solar Probe (WISPR), and maybe for future real time predictions when STEREO-A approaches the L5 point. Title: Prospective White-light Imaging and In Situ Measurements of Quiescent Large-scale Solar-wind Streams from the Parker Solar Probe and Solar Orbiter Authors: Xiong, Ming; Davies, Jackie A.; Feng, Xueshang; Li, Bo; Yang, Liping; Xia, Lidong; Harrison, Richard A.; Hayashi, Keiji; Li, Huichao; Zhou, Yufen Bibcode: 2018ApJ...868..137X Altcode: Deep-space exploration of the inner heliosphere is in an unprecedented golden age, with the recent and forthcoming launches of the Parker Solar Probe (PSP) and Solar Orbiter (SolO) missions, respectively. In order to both predict and understand the prospective observations by PSP and SolO, we perform forward MHD modeling of the 3D inner heliosphere at solar minimum, and synthesize the white-light (WL) emission that would result from Thomson scattering of sunlight from the coronal and heliospheric plasmas. Both solar rotation and spacecraft trajectory should be considered when reconstructing quiescent large-scale solar-wind streams from PSP and SolO WL observations. When transformed from a static coordinate system into a corotating one, the elliptical orbit of PSP becomes a multiwinding spiral. The innermost spiral winding of this corotating PSP orbit takes the form of a closed “heart shape” within around 80 R of the Sun. PSP, when traveling along this “heart-shaped” trajectory, can cross a single corotating interaction region (CIR) twice. This enables in situ measurements of the same CIR to be made in both the corona and heliosphere. As PSP approaches perihelion, the WL radiance from the corona increases. Polarization can be used to localize the main WL scattering region in the corona. Large-scale structures around PSP can be further resolved in the longitudinal dimension, using additional WL imagery from the out-of-ecliptic perspective of SolO. Coordinated observations between PSP and SolO are very promising in the quest to differentiate background CIRs from transient ejecta. Title: Space weather in the UK Authors: Bisi, Mario; Hapgood, Mike; Bisi, Mario M.; Harrison, Richard Bibcode: 2018cosp...42E.357B Altcode: The UK Government's inclusion of severe space weather on the National Risk Register (NRR) of Civil Emergencies in recent years has led to a somewhat co-ordinated, yet wide-ranging set of activities that is attempting to tackle space weather threats at the national level, but incorporating active engagement on the international scene. Two immediate responses to the Government's decision in managing the space weather risk are: (a) the setting up of a UK space weather forecasting centre at the Met Office, in Exeter (UK) - which is only one of two civil forecasting centres world-wide that are manned 24 hours a day, 7 days a week; and (b) the formation of the Space Environment Impacts Expert Group (SEIEG), chaired by Prof. Mike Hapgood from STFC RAL Space, that advises the UK Cabinet Office and the Government Department of Business, Energy and Industrial Strategy. These activities have come about from active partnerships between agencies, industrial groups, and the science community to ensure that the wide range of issues involved are fully covered. In parallel, the UK Space Agency (UKSA), in responding to these activities and engaging with key institutes such as the STFC Rutherford Appleton Laboratory (RAL) and the Met Office, has become a major supporter of the emerging ESA Space Situational Awareness (SSA) space weather programme, which ultimately ensured that the UK has taken leadership roles in the instrument development activities for the planned Lagrange L5 space weather mission as well as in service activities such as the Heliospheric Expert Service Centre. All of these activities, and more, have come about because of extensive dialogue between the academic community, the industrial community, the relevant agencies, and Government in the UK, as well as with international groups such as ESA and NOAA. The strategic approach in the UK has been particularly successful and continues to evolve. Of particular interest in the coming years is the development of the role of the UN COPUOS and COSPAR, with which the UK will be fully engaged. Title: Numerically calibrated model for propagation of a relativistic unmagnetized jet in dense media Authors: Harrison, Richard; Gottlieb, Ore; Nakar, Ehud Bibcode: 2018MNRAS.477.2128H Altcode: 2017arXiv170706234H; 2018MNRAS.tmp..736H Relativistic jets reside in high-energy astrophysical systems of all scales. Their interaction with the surrounding media is critical as it determines the jet evolution, observable signature, and feedback on the environment. During its motion, the interaction of the jet with the ambient media inflates a highly pressurized cocoon, which under certain conditions collimates the jet and strongly affects its propagation. Recently, Bromberg et al. derived a general simplified (semi-)analytic solution for the evolution of the jet and the cocoon in case of an unmagnetized jet that propagates in a medium with a range of density profiles. In this work we use a large suite of 2D and 3D relativistic hydrodynamic simulations in order to test the validity and accuracy of this model. We discuss the similarities and differences between the analytic model and numerical simulations and also, to some extent, between 2D and 3D simulations. Our main finding is that although the analytic model is highly simplified, it properly predicts the evolution of the main ingredients of the jet-cocoon system, including its temporal evolution and the transition between various regimes (e.g. collimated to uncollimated). The analytic solution predicts a jet head velocity that is faster by a factor of about 3 compared to the simulations, as long as the head velocity is Newtonian. We use the results of the simulations to calibrate the analytic model which significantly increases its accuracy. We provide an applet that calculates semi-analytically the propagation of a jet in an arbitrary density profile defined by the user at http://www.astro.tau.ac.il/∼ore/propagation.html. Title: Coronal Magnetic Structure of Earthbound CMEs and In Situ Comparison Authors: Palmerio, E.; Kilpua, E. K. J.; Möstl, C.; Bothmer, V.; James, A. W.; Green, L. M.; Isavnin, A.; Davies, J. A.; Harrison, R. A. Bibcode: 2018SpWea..16..442P Altcode: 2018arXiv180304769P Predicting the magnetic field within an Earth-directed coronal mass ejection (CME) well before its arrival at Earth is one of the most important issues in space weather research. In this article, we compare the intrinsic flux rope type, that is, the CME orientation and handedness during eruption, with the in situ flux rope type for 20 CME events that have been uniquely linked from Sun to Earth through heliospheric imaging. Our study shows that the intrinsic flux rope type can be estimated for CMEs originating from different source regions using a combination of indirect proxies. We find that only 20% of the events studied match strictly between the intrinsic and in situ flux rope types. The percentage rises to 55% when intermediate cases (where the orientation at the Sun and/or in situ is close to 45°) are considered as a match. We also determine the change in the flux rope tilt angle between the Sun and Earth. For the majority of the cases, the rotation is several tens of degrees, while 35% of the events change by more than 90°. While occasionally the intrinsic flux rope type is a good proxy for the magnetic structure impacting Earth, our study highlights the importance of capturing the CME evolution for space weather forecasting purposes. Moreover, we emphasize that determination of the intrinsic flux rope type is a crucial input for CME forecasting models. Title: CMEs in the Heliosphere: I. A Statistical Analysis of the Observational Properties of CMEs Detected in the Heliosphere from 2007 to 2017 by STEREO/HI-1 Authors: Harrison, R. A.; Davies, J. A.; Barnes, D.; Byrne, J. P.; Perry, C. H.; Bothmer, V.; Eastwood, J. P.; Gallagher, P. T.; Kilpua, E. K. J.; Möstl, C.; Rodriguez, L.; Rouillard, A. P.; Odstrčil, D. Bibcode: 2018SoPh..293...77H Altcode: 2018arXiv180402320H We present a statistical analysis of coronal mass ejections (CMEs) imaged by the Heliospheric Imager (HI) instruments on board NASA's twin-spacecraft STEREO mission between April 2007 and August 2017 for STEREO-A and between April 2007 and September 2014 for STEREO-B. The analysis exploits a catalogue that was generated within the FP7 HELCATS project. Here, we focus on the observational characteristics of CMEs imaged in the heliosphere by the inner (HI-1) cameras, while following papers will present analyses of CME propagation through the entire HI fields of view. More specifically, in this paper we present distributions of the basic observational parameters - namely occurrence frequency, central position angle (PA) and PA span - derived from nearly 2000 detections of CMEs in the heliosphere by HI-1 on STEREO-A or STEREO-B from the minimum between Solar Cycles 23 and 24 to the maximum of Cycle 24; STEREO-A analysis includes a further 158 CME detections from the descending phase of Cycle 24, by which time communication with STEREO-B had been lost. We compare heliospheric CME characteristics with properties of CMEs observed at coronal altitudes, and with sunspot number. As expected, heliospheric CME rates correlate with sunspot number, and are not inconsistent with coronal rates once instrumental factors/differences in cataloguing philosophy are considered. As well as being more abundant, heliospheric CMEs, like their coronal counterparts, tend to be wider during solar maximum. Our results confirm previous coronagraph analyses suggesting that CME launch sites do not simply migrate to higher latitudes with increasing solar activity. At solar minimum, CMEs tend to be launched from equatorial latitudes, while at maximum, CMEs appear to be launched over a much wider latitude range; this has implications for understanding the CME/solar source association. Our analysis provides some supporting evidence for the systematic dragging of CMEs to lower latitude as they propagate outwards. Title: Prospective Out-of-ecliptic White-light Imaging of CIRs and CMEs through the Corona and Heliosphere Authors: Xiong, Ming; Davies, Jackie; Feng, Xueshang; Harrison, Richard; Xia, Lidong; Yang, Liping; Zhou, Yufen; Liu, Ying; Li, Bo Bibcode: 2018EGUGA..20.3905X Altcode: Interplanetary corotating interaction regions (CIRs) and coronal mass ejections (CMEs) can be remotely imaged in white light (WL), as demonstrated by the in-flight performance of the Coriolis/SMEI and STEREO/HI instruments. Because of the in-ecliptic locations of both the STEREO and Coriolis spacecraft, the longitudinal dimension of interplanetary CIRs and CMEs has, up to now, always been integrated in WL imagery. To synthesize the WL radiance patterns of CIRs and CMEs from an out-of-ecliptic (OOE) vantage point, we perform forward magnetohydrodynamic (MHD) modeling of the background solar wind flow at solar maximum and a halo CME at solar minimum. We assert that a panoramic OOE view in WL would be highly beneficially in revealing the morphology and kinematics of CIRs and CMEs in the hitherto unresolved longitudinal dimension, and hence for monitoring the propagation and evolution of inecliptic CMEs for space weather operations. Title: Key results and services of HELCATS Authors: Bothmer, Volker; Harrison, Richard; Davies, Jackie; Rouillard, Alexis Bibcode: 2018EGUGA..20.7441B Altcode: The EU FP7 project HELCATS (HELIOSPHERIC CATALOGUING, ANALYSIS & TECHNIQUES SERVICE) has provided new insights into solar wind structure through combining the comprehensive analysis of heliospheric imaging observations from the NASA STEREO spacecraft, in concert with associated remote-sensing and in-situ measurements, with a thorough assessment of appropriate techniques and models. The project recognised that the advent of wide-angle imaging of the inner heliosphere has revolutionised the study of transient and quasi-stationary structures in the solar wind, in particular Coronal Mass Ejections (CMEs) and Co-rotating Interaction Regions (CIRs). Prior to the development of wide-angle imaging of the inner heliosphere, signatures of such solar wind features could only be observed within a few solar radii of the Sun, and in the vicinity of a few near-Earth and interplanetary probes making in-situ measurements of the solar wind. Heliospheric imaging has, for the first time, filled that vast and crucial observational gap. This presentation summarises the key results and services established by the HELCATS project. Title: Prospective Out-of-ecliptic White-light Imaging of Coronal Mass Ejections Traveling through the Corona and Heliosphere Authors: Xiong, Ming; Davies, Jackie A.; Harrison, Richard A.; Zhou, Yufen; Feng, Xueshang; Xia, Lidong; Li, Bo; Liu, Ying D.; Hayashi, Keiji; Li, Huichao; Yang, Liping Bibcode: 2018ApJ...852..111X Altcode: The in-flight performance of the Coriolis/SMEI and STEREO/HI instruments substantiates the high-technology readiness level of white-light (WL) imaging of coronal mass ejections (CMEs) in the inner heliosphere. The WL intensity of a propagating CME is jointly determined by its evolving mass distribution and the fixed Thomson-scattering geometry. From their in-ecliptic viewpoints, SMEI and HI, the only heliospheric imagers that have been flown to date, integrate the longitudinal dimension of CMEs. In this paper, using forward magnetohydrodynamic modeling, we synthesize the WL radiance pattern of a typical halo CME viewed from an out-of-ecliptic (OOE) vantage point. The major anatomical elements of the CME identified in WL imagery are a leading sheath and a trailing ejecta; the ejecta-driven sheath is the brightest feature of the CME. The sheath, a three-dimensional (3D) dome-like density structure, occupies a wide angular extent ahead of the ejecta itself. The 2D radiance pattern of the sheath depends critically on viewpoint. For a CME modeled under solar minimum conditions, the WL radiance pattern of the sheath is generally a quasi-straight band when viewed from an in-ecliptic viewpoint and a semicircular arc from an OOE viewpoint. The dependence of the radiance pattern of the ejecta-driven sheath on viewpoint is attributed to the bimodal nature of the 3D background solar wind flow. Our forward-modeling results suggest that OOE imaging in WL radiance can enable (1) a near-ecliptic CME to be continuously tracked from its coronal initiation, (2) the longitudinal span of the CME to be readily charted, and (3) the transporting speed of the CME to be reliably determined. Additional WL polarization measurements can significantly limit the ambiguity of localizing CMEs. We assert that a panoramic OOE view in WL would be highly beneficial in revealing CME morphology and kinematics in the hitherto-unresolved longitudinal dimension and hence for monitoring the propagation and evolution of near-ecliptic CMEs for space weather operations. Title: The Heliospheric Cataloguing, Analysis and Techniques Service (HELCATS) project Authors: Barnes, D.; Harrison, R. A.; Davies, J. A.; Perry, C. H.; Moestl, C.; Rouillard, A.; Bothmer, V.; Rodriguez, L.; Eastwood, J. P.; Kilpua, E.; Gallagher, P.; Odstrcil, D. Bibcode: 2017AGUFMSH31A2713B Altcode: Understanding solar wind evolution is fundamental to advancing our knowledge of energy and mass transport in the solar system, whilst also being crucial to space weather and its prediction. The advent of truly wide-angle heliospheric imaging has revolutionised the study of solar wind evolution, by enabling direct and continuous observation of both transient and background components of the solar wind as they propagate from the Sun to 1 AU and beyond. The recently completed, EU-funded FP7 Heliospheric Cataloguing, Analysis and Techniques Service (HELCATS) project (1st May 2014 - 30th April 2017) combined European expertise in heliospheric imaging, built up over the last decade in particular through leadership of the Heliospheric Imager (HI) instruments aboard NASA's STEREO mission, with expertise in solar and coronal imaging as well as the interpretation of in-situ and radio diagnostic measurements of solar wind phenomena. HELCATS involved: (1) the cataloguing of transient (coronal mass ejections) and background (stream/corotating interaction regions) solar wind structures observed by the STEREO/HI instruments, including estimates of their kinematic properties based on a variety of modelling techniques; (2) the verification of these kinematic properties through comparison with solar source observations and in-situ measurements at multiple points throughout the heliosphere; (3) the assessment of the potential for initialising numerical models based on the derived kinematic properties of transient and background solar wind components; and (4) the assessment of the complementarity of radio observations (Type II radio bursts and interplanetary scintillation) in the detection and analysis of heliospheric structure in combination with heliospheric imaging observations. In this presentation, we provide an overview of the HELCATS project emphasising, in particular, the principal achievements and legacy of this unprecedented project. Title: Modeling observations of solar coronal mass ejections with heliospheric imagers verified with the Heliophysics System Observatory Authors: Möstl, C.; Isavnin, A.; Boakes, P. D.; Kilpua, E. K. J.; Davies, J. A.; Harrison, R. A.; Barnes, D.; Krupar, V.; Eastwood, J. P.; Good, S. W.; Forsyth, R. J.; Bothmer, V.; Reiss, M. A.; Amerstorfer, T.; Winslow, R. M.; Anderson, B. J.; Philpott, L. C.; Rodriguez, L.; Rouillard, A. P.; Gallagher, P.; Nieves-Chinchilla, T.; Zhang, T. L. Bibcode: 2017SpWea..15..955M Altcode: 2017arXiv170300705M We present an advance toward accurately predicting the arrivals of coronal mass ejections (CMEs) at the terrestrial planets, including Earth. For the first time, we are able to assess a CME prediction model using data over two thirds of a solar cycle of observations with the Heliophysics System Observatory. We validate modeling results of 1337 CMEs observed with the Solar Terrestrial Relations Observatory (STEREO) heliospheric imagers (HI) (science data) from 8 years of observations by five in situ observing spacecraft. We use the self-similar expansion model for CME fronts assuming 60° longitudinal width, constant speed, and constant propagation direction. With these assumptions we find that 23%-35% of all CMEs that were predicted to hit a certain spacecraft lead to clear in situ signatures, so that for one correct prediction, two to three false alarms would have been issued. In addition, we find that the prediction accuracy does not degrade with the HI longitudinal separation from Earth. Predicted arrival times are on average within 2.6 ± 16.6 h difference of the in situ arrival time, similar to analytical and numerical modeling, and a true skill statistic of 0.21. We also discuss various factors that may improve the accuracy of space weather forecasting using wide-angle heliospheric imager observations. These results form a first-order approximated baseline of the prediction accuracy that is possible with HI and other methods used for data by an operational space weather mission at the Sun-Earth L5 point. Title: Prospective Out-of-ecliptic White-light Imaging of Interplanetary Corotating Interaction Regions at Solar Maximum Authors: Xiong, Ming; Davies, Jackie A.; Li, Bo; Yang, Liping; Liu, Ying D.; Xia, Lidong; Harrison, Richard A.; Keiji, Hayashi; Li, Huichao Bibcode: 2017ApJ...844...76X Altcode: Interplanetary corotating interaction regions (CIRs) can be remotely imaged in white light (WL), as demonstrated by the Solar Mass Ejection Imager (SMEI) on board the Coriolis spacecraft and Heliospheric Imagers (HIs) on board the twin Solar TErrestrial RElations Observatory (STEREO) spacecraft. The interplanetary WL intensity, due to Thomson scattering of incident sunlight by free electrons, is jointly determined by the 3D distribution of electron number density and line-of-sight (LOS) weighting factors of the Thomson-scattering geometry. The 2D radiance patterns of CIRs in WL sky maps look very different from different 3D viewpoints. Because of the in-ecliptic locations of both the STEREO and Coriolis spacecraft, the longitudinal dimension of interplanetary CIRs has, up to now, always been integrated in WL imagery. To synthesize the WL radiance patterns of CIRs from an out-of-ecliptic (OOE) vantage point, we perform forward magnetohydrodynamic modeling of the 3D inner heliosphere during Carrington Rotation CR1967 at solar maximum. The mixing effects associated with viewing 3D CIRs are significantly minimized from an OOE viewpoint. Our forward modeling results demonstrate that OOE WL imaging from a latitude greater than 60° can (1) enable the garden-hose spiral morphology of CIRs to be readily resolved, (2) enable multiple coexisting CIRs to be differentiated, and (3) enable the continuous tracing of any interplanetary CIR back toward its coronal source. In particular, an OOE view in WL can reveal where nascent CIRs are formed in the extended corona and how these CIRs develop in interplanetary space. Therefore, a panoramic view from a suite of wide-field WL imagers in a solar polar orbit would be invaluable in unambiguously resolving the large-scale longitudinal structure of CIRs in the 3D inner heliosphere. Title: Cataloguing radio emission associated with coronal mass ejections: results from the HELCATS project Authors: Eastwood, Jonathan; Krupar, Vratislav; Magdalenic, Jasmina; Bisi, Mario; Gopalswamy, Nat; Davies, Jackie; Harrison, Richard; Barnes, David Bibcode: 2017EGUGA..19.5249E Altcode: The goal of the Heliospheric Cataloguing, Analysis and Techniques Service (HELCATS) is to add value to the STEREO dataset by cataloguing the properties of coronal mass ejections and corotating interaction regions observed by STEREO. As part of this work, the complementary nature of radio measurements and white light observations has been assessed. Here we report on the cataloguing of slowly-drifting radio emission observed by STEREO WAVES in conjunction with events identified in the HELCATS manually-generated coronal mass ejection catalogue. We present preliminary statistical results derived from the catalogue, in particular the extent to which radio emission is more likely to occur in conjunction with fast coronal mass ejections. We further use the catalogue to make an initial assessment of the angular deviation between radio emission and coronal mass ejection motion, in order to determine which part of the coronal mass ejection contributes most to the radio emission. HELCATS is project 606692 of the European Union's Seventh Framework Programme. Title: CME properties and solar source region characteristics - HELCATS results Authors: Bothmer, Volker; Mrotzek, Niclas; Murray, Sophie; Gallagher, Peter; Barnes, David; Davies, Jackie; Harrison, Richard Bibcode: 2017EGUGA..19.5107B Altcode: One objective of the EU FP7 project HELCATS is to derive and catalogue the characteristics of CMEs observed with the STEREO/COR2 & HI imagers based on geometrical and forward modelling. Here we present the results of the analysis of a subset of the 122 CME events that have been dynamically modelled with the GCS-method in the COR2 field of view and which are compiled in the KINCAT database at http://www.affects-fp7.eu/helcats-database/database.php. The CME properties, such as speeds, masses, angular widths, as derived from modelling, are compared with magnetic field properties of the corresponding solar source active region, such as magnetic flux, area, and polarity line characteristics. The results show which solar parameters define the structure of CMEs at distances around 12 solar radii and how they can be used for space weather forecast services. Title: Using helispheric imager observations in predicting the impact of coronal mass ejections (CMEs) at planets Authors: Kilpua, Emilia; Möstl, Christian; Bothmer, Volker; Isavnin, Alexey; Harrison, Richard; Davies, Jackie; Palmerio, Erika; Boakes, Peter; Mrotzek, Niclas Bibcode: 2017EGUGA..19.9051K Altcode: Connecting coronal mass ejections (CMEs) in remote-sensing and in-situ observations can be surprisingly difficult. Coronagraphs can detect CMEs only about 10% of their journey from Sun to 1 AU. One viable way to track CMEs through the inner heliosphere is using heliospheric imaging. HELCATS (Heliospheric Cataloguing, Analysis And Techniques Service) LINKCAT catalogue is the first concerted effort to establish such linkage automatically by the systematic use of STEREO Heliospheric Imager (HI) observations and related modelling. This presentation gives and overview of how the LINKCAT catalogue is generated and evaluates the potential of HI-based imagining in connecting CMEs near the Sun and in-situ. We will also discuss the possible problems in our approach and the key future improvements. Title: EU HELCATS Project WP7: Combining Observations of Interplanetary Scintillation (IPS) and Heliospheric Visible-Light Imaging of CMEs and SIRs for Space-Weather Purposes Authors: Bisi, Mario Mark; Barnes, David; Eastwood, Jonathan; Krupar, Vratislav; Magdalenic, Jasmina; Harrison, Richard; Davies, Jackie; Fallows, Richard Bibcode: 2017EGUGA..1912991B Altcode: The Heliospheric Cataloguing, Analysis and Techniques Service (HELCATS) project is one of the European Union's Seventh Framework Programme (EU FP7) projects. The project is primarily targeted to the cataloguing of transient and background structures observed in the heliosphere by the visible-light Heliospheric Imagers (HIs) on board the twin spacecraft STEREO mission, including identification of their source regions and in-situ signatures. The current version of the HELCATS manually-generated Coronal Mass Ejection (CME) Catalogue contains more than 1,000 CMEs observed between 2007 and 2016, and the current HELCATS Stream Interaction Region (SIR) Catalogue contains signatures of nearly 200 co-rotating density structures in the ecliptic plane. HELCATS also includes an assessment of the complementary nature of ground-based radio observations of interplanetary scintillation (IPS), which is yielding catalogues of IPS features (from EISCAT/MERLIN/ESR and/or LOFAR data, where available) that are being compared to the STEREO HI catalogues. Here we discuss the near-final status of this aspects of HELCATS and provide any insights that have been gleaned from initial analyses of this joint cataloguing exercise. Such insights relate, in particular, to the space-weather exploitation of these two complementary observational techniques. For example, there are cases where a CME is imaged by the STEREO HI instruments but then not detected using IPS, and vice versa, and preliminary investigations of these will be discussed. Title: A Catalogue of Coronal Mass Ejections Observed by the STEREO Heliospheric Imagers: Results from HELCATS Authors: Barnes, David; Davies, Jackie; Harrison, Richard; Perry, Chris; Möstl, Christian; Rouillard, Alexis; Bothmer, Volker; Rodriguez, Luciano; Eastwood, Jonathan; Kilpua, Emilia; Gallagher, Peter Bibcode: 2017EGUGA..19.8160B Altcode: The wide fields of view provided by the STEREO Heliospheric Imagers (HIs) allow far greater coverage of Coronal Mass Ejections (CMEs) than are typically available from coronagraph observations. As part of the EU FP7 HELCATS (Heliospheric Cataloguing, Analysis and Techniques Service) project we present a comprehensive catalogue of CMEs that are observed in HI data, throughout the lifetime of the instruments. This spans the period from April 2007 to September 2014 for both STEREO-A and -B, with additional STEREO-A observations continuing from October 2015 to present, covering the majority of solar cycle 24. A subset of these CMEs are tracked through the HI fields of view, to which we apply both single-spacecraft and stereoscopic models to determine CME kinematic properties such as propagation directions, speeds and accelerations. The statistical properties of these results are discussed and they are compared with coronagraph observations during the same period. Title: A Multi-Model Approach to the Analysis of the Kinematics of CMEs Based on Multi-point Space Observations Authors: Mrotzek, Niclas; Bothmer, Volker; Davies, Jackie; Harrison, Richard Bibcode: 2017EGUGA..19.3532M Altcode: The interaction between Coronal Mass Ejections (CMEs) and the ambient solar wind is a crucial factor affecting their interplanetary evolution. It is believed that acceleration due to the Lorenz force dominates CME evolution near the Sun and that the aerodynamic drag force becomes dominant further away. In this study, we present results of a distance-dependent aerodynamic drag force model taking into account solar wind measurements from the Helios spacecraft over the spatial range 0.3 to 0.9 AU. We undertake GCS modelling of the investigated CMEs based on observations from the coronagraphs on SOHO and STEREO as well as observations from the STEREO heliospheric imagers (HIs). Application of the CGS modelling to the HI data enables the height-time profiles of the CMEs to be extended further from the Sun. To derive transit times to 1 AU, the height-time profiles are then fitted using a kinematic drag model and compared with in-situ solar wind measurements. The study is carried out in the framework of the EU FP7 project HELCATS (Heliospheric Cataloguing, Analysis and Techniques Service). Title: Modeling of coronal mass ejections with the STEREO heliospheric imagers verified with in situ observations by the Heliophysics System Observatory Authors: Möstl, Christian; Isavnin, Alexey; Kilpua, Emilia; Bothmer, Volker; Mrotzek, Nicolas; Boakes, Peter; Rodriguez, Luciano; Krupar, Vratislav; Eastwood, Jonathan; Davies, Jackie; Harrison, Richard; Barnes, David; Winslow, Reka; Helcats Team Bibcode: 2017EGUGA..19.4536M Altcode: We present the first study to verify modeling of CMEs as observed by the heliospheric imagers on the two STEREO spacecraft with a large scale dataset of in situ plasma and magnetic field observations from the Heliophysics System Observatory, including MESSENGER, VEX, Wind, and the in situ measurements on the two STEREO spacecraft. To this end, we have established a new interplanetary CME catalog (ICMECAT) for these spacecraft by gathering and updating individual ICME lists. In addition, we have re-calculated the in situ parameters in a consistent way, resulting in 668 events observed between 2007-2015. We then calculated the efficacy of the STEREO/HI instruments for predicting (in hindsight) with the SSEF30 model the arrival time and speed of CMEs as well as hit/miss ratios. We also show how ICMECAT gives decent statistics concerning CME impacts on all of the terrestrial planets, including Mars. The results show some major implications for future heliospheric imagers which may be used for space weather forecasting. Our effort should also serve as a baseline for the upcoming new era in heliospheric science with Solar Orbiter, Solar Probe Plus, BepiColombo returning partly comparable observations in the next decade. The presented work has received funding from the European Union Seventh Framework Programme (FP7/ 2007-2013) under grant agreement No. 606692 [HELCATS]. Title: Long-Term Tracking of Corotating Density Structures Using Heliospheric Imaging (catalogue of CIRs during 2007-2014) Authors: Plotnikov, Illya; Rouillard, Alexis P.; Davies, Jackie; Botmer, Volker; Eastwood, Jonathan; Gallagher, Peter; Harrison, Richard; Kilpua, Emilia; Möstl, Christian C.; Perry, Chris; Rodriguez, Luciano; Lavraud, Benoit; Genot, Vincent; Pinto, Rui; Sanchez-Diaz, Eduardo Bibcode: 2017EGUGA..19.4486P Altcode: The systematic monitoring of the solar wind in high-cadence and high-resolution heliospheric images taken by the Solar-Terrestrial Relation Observatory (STEREO) spacecraft permits the study of the spatial and temporal evolution of variable solar wind flows from the Sun out to 1 AU, and beyond. As part of the EU Framework 7 (FP7) Heliospheric Cataloguing, Analysis and Techniques Service (HELCATS) project, we have generated a catalogue listing the properties of more than 190 corotating structures well-observed in images taken by the Heliospheric Imager (HI) instruments on-board STEREO-A (ST-A). Based on this catalogue, we present here one of very few long-term analyses of solar wind structures advected by the background solar wind. We concentrate on the subset of plasma density structures clearly identified inside corotating structures. This analysis confirms that most of the corotating density structures detected by the heliospheric imagers comprises a series of density inhomogeneities advected by the slow solar wind that eventually become entrained by stream interaction regions. We have derived the spatial-temporal evolution of each of these corotating density structures by using a well-established fitting technique. The mean radial propagation speed of the corotating structures is found to be 311 ± 31 km s-1. We show that the speeds of the corotating density structures derived using our fitting technique track well the long-term variation of the radial speed of the slow solar wind during solar minimum years (2007-2008). Furthermore, we demonstrate that these features originate near the coronal neutral line that eventually becomes the heliospheric current sheet. Title: Overview of the HELCATS project Authors: Harrison, Richard; Davies, Jackie; Perry, Chris; Moestl, Christian; Rouillard, Alexis; Bothmer, Volker; Rodriguez, Luciano; Eastwood, Jonathan; Kilpua, Emilia; Gallagher, Peter; Odstrcil, Dusan Bibcode: 2017EGUGA..19.5296H Altcode: Understanding solar wind evolution is fundamental to advancing our knowledge of energy and mass transport in the solar system, whilst also being crucial to space weather and its prediction. The advent of truly wide-angle heliospheric imaging has revolutionised the study of solar wind evolution, by enabling direct and continuous observation of both transient and background components of the solar wind as they propagate from the Sun to 1 AU and beyond. The EU-funded FP7 Heliospheric Cataloguing, Analysis and Techniques Service (HELCATS) project combines European expertise in heliospheric imaging, built up over the last decade in particular through lead involvement in NASA's STEREO mission, with expertise in solar and coronal imaging as well as the interpretation of in-situ and radio diagnostic measurements of solar wind phenomena. HELCATS involves: (1) cataloguing of transient (coronal mass ejections) and background (stream/corotating interaction regions) solar wind structures observed by the STEREO/Heliospheric Imagers, including estimates of their kinematic properties based on a variety of modelling techniques; (2) verifying these kinematic properties through comparison with solar source observations and in-situ measurements at multiple points throughout the heliosphere; (3) assessing the potential for initialising numerical models based on the derived kinematic properties of transient and background solar wind components; (4) assessing the complementarity of radio observations (Type II radio bursts and interplanetary scintillation) in the detection and analysis of heliospheric structure in combination with heliospheric imaging observations. We provide an overview of the achievements of the HELCATS project, as it reaches its conclusion, and present selected results that seek to illustrate the value and legacy of this unprecedented, coordinated study of structures in the heliosphere. Title: Magnetic structure of Earth-directed events in the HELCATS LINKCAT catalog during 2011-2013 Authors: Palmerio, Erika; Kilpua, Emilia; Bothmer, Volker; Isavnin, Alexey; Möstl, Christian; Green, Lucie; James, Alexander; Davies, Jackie; Harrison, Richard Bibcode: 2017EGUGA..19.3874P Altcode: Coronal mass ejections (CMEs) are the main drivers of intense magnetic storms and various subsequent space weather phenomena at Earth. The parameter that defines the ability of a CME to drive geomagnetic storms is the north-south magnetic field component. One of the most significant problems in current long-term space weather forecasts is that there is no practical method to measure the magnetic structure of CMEs routinely in the outer corona. The magnetic structure of CME flux ropes can however be inferred based on the properties of the CME's source region characteristics, such as filament details, coronal EUV arcades, X-ray sigmoids, taking into account nearby coronal and photospheric features. The linked catalogue (LINKCAT) of solar CMEs during the STEREO era is part of the HELCATS project. It aims at connecting CME observations at the Sun and in interplanetary space, using heliospheric imager observations from the HI1 cameras onboard the two STEREO spacecraft to connect the different datasets. The HELCATS LINKCAT catalogue contains 45 Earth-directed events in the period 2011-2013 (https://www.helcats-fp7.eu/catalogues/wp4_cat.html). Here we present a statistical study based on the LINKCAT Earth-directed events during 2011-2013 in which we determine the magnetic properties of the erupting CMEs, i.e. their magnetic helicity sign, flux rope tilt, and flux rope axial field direction, by using a synthesis of indirect proxies based on multi-wavelength remote sensing observations from the STEREO, SOHO, Hinode, and SDO satellites. These parameters define the ``intrinsic'' flux rope configuration at the time of the eruption which is compared with the magnetic structures detected in situ near Earth. Title: HELCATS: Statistical results on interplanetary type II bursts observed by STEREO/Waves Authors: Krupar, V.; Eastwood, J. P.; Magdalenic, J.; Gopalswamy, N.; Bisi, M. M.; Davies, J. A.; Harrison, R. A.; Barnes, D. Bibcode: 2016AGUFMSH11C2246K Altcode: Heliospheric Cataloguing, Analysis and Techniques Service (HELCATS) is a project of the European Union's Seventh Framework Programme. The current version of the HELCATS manually-generated Coronal Mass Ejection (CME) catalogue contains more than 1,300 CMEs observed between 2007 and 2014. CMEs are sometimes associated with the so called type II bursts which are considered to be radio signatures of fast electrons accelerated at the CME-driven shock front. We present statistical results on 153 type II bursts associated with manually-identified CMEs in the HELCATS catalogue. We found that faster CMEs are more likely to produce radio emissions. By comparing frequency drifts with white-light observations we calculated angular deviations of type II burst propagation directions from radial. Our results confirm that type II bursts statistically arise from CME flanks. We also discuss the use of interplanetary radio emission in the context of space weather forecasting. Title: A Catalogue of Geometrically-Modelled Coronal Mass Ejections Observed by the STEREO Heliospheric Imagers Authors: Barnes, D.; Davies, J. A.; Harrison, R. A.; Perry, C. H.; Moestl, C.; Rouillard, A.; Bothmer, V.; Rodriguez, L.; Eastwood, J. P.; Kilpua, E.; Gallagher, P. Bibcode: 2016AGUFMSH31B2588B Altcode: We present a catalogue of Coronal Mass Ejections (CMEs) observed by the Heliospheric Imagers (HIs) onboard the two NASA STEREO spacecraft. This catalogue contains all CMEs observed during the operational phase of the STEREO mission, April 2007 to September 2014, for both spacecraft and resumes from November 2015 for STEREO-A. These CMEs are tracked using time-elongation plots through the HI-1 and HI-2 fields of view and to them we apply geometric models to determine their kinematic properties, such as speed, propagation direction and launch time. A subset of these CMEs, which are observed simultaneously by both spacecraft, are identified and to which stereoscopic modelling techniques are applied. The statistical properties of these catalogues are discussed as are their results compared to existing CME catalogues covering the same periods. This work is carried out as part of the EU FP7 HELCATS (Heliospheric Cataloguing, Analysis and Techniques Service) project. Title: Erratum: “ElEvoHI: A Novel CME Prediction Tool for Heliospheric Imaging Combining an Elliptical Front with Drag-based Model Fitting” (ApJ, 824, 2, 131) Authors: Amerstorfer, T.; Möstl, C.; Isavnin, A.; Davies, J. A.; Kubicka, M.; Amerstorfer, U. V.; Harrison, R. A. Bibcode: 2016ApJ...831..210A Altcode: No abstract at ADS 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: Long-Term Tracking of Corotating Density Structures Using Heliospheric Imaging Authors: Plotnikov, I.; Rouillard, A. P.; Davies, J. A.; Bothmer, V.; Eastwood, J. P.; Gallagher, P.; Harrison, R. A.; Kilpua, E.; Möstl, C.; Perry, C. H.; Rodriguez, L.; Lavraud, B.; Génot, V.; Pinto, R. F.; Sanchez-Diaz, E. Bibcode: 2016SoPh..291.1853P Altcode: 2016SoPh..tmp..118P; 2016arXiv160601127P The systematic monitoring of the solar wind in high-cadence and high-resolution heliospheric images taken by the Solar-Terrestrial Relation Observatory (STEREO) spacecraft permits the study of the spatial and temporal evolution of variable solar wind flows from the Sun out to 1 AU, and beyond. As part of the EU Framework 7 (FP7) Heliospheric Cataloguing, Analysis and Techniques Service (HELCATS) project, we have generated a catalog listing the properties of 190 corotating structures well-observed in images taken by the Heliospheric Imager (HI) instruments onboard STEREO-A (ST-A). Based on this catalog, we present here one of very few long-term analyses of solar wind structures advected by the background solar wind. We concentrate on the subset of plasma density structures clearly identified inside corotating structures. This analysis confirms that most of the corotating density structures detected by the heliospheric imagers comprises a series of density inhomogeneities advected by the slow solar wind that eventually become entrained by stream interaction regions. We have derived the spatial-temporal evolution of each of these corotating density structures by using a well-established fitting technique. The mean radial propagation speed of the corotating structures is found to be 311 ±31 kms−1. Such a low mean value corresponds to the terminal speed of the slow solar wind rather than the speed of stream interfaces, which is typically intermediate between the slow and fast solar wind speeds (∼400 kms−1). Using our fitting technique, we predicted the arrival time of each corotating density structure at different probes in the inner heliosphere. We find that our derived speeds are systematically lower by ∼100 kms−1 than those measured in situ at the predicted impact times. Moreover, for cases when a stream interaction region is clearly detected in situ at the estimated impact time, we find that our derived speeds are lower than the speed of the stream interface measured in situ by an average of 55 kms−1 at ST-A and 84 kms−1 at STEREO-B (ST-B). We show that the speeds of the corotating density structures derived using our fitting technique track well the long-term variation of the radial speed of the slow solar wind during solar minimum years (2007 - 2008). Furthermore, we demonstrate that these features originate near the coronal neutral line that eventually becomes the heliospheric current sheet. 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: 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: ElEvoHI: A Novel CME Prediction Tool for Heliospheric Imaging Combining an Elliptical Front with Drag-based Model Fitting Authors: Rollett, T.; Möstl, C.; Isavnin, A.; Davies, J. A.; Kubicka, M.; Amerstorfer, U. V.; Harrison, R. A. Bibcode: 2016ApJ...824..131R Altcode: 2016arXiv160500510R In this study, we present a new method for forecasting arrival times and speeds of coronal mass ejections (CMEs) at any location in the inner heliosphere. This new approach enables the adoption of a highly flexible geometrical shape for the CME front with an adjustable CME angular width and an adjustable radius of curvature of its leading edge, I.e., the assumed geometry is elliptical. Using, as input, Solar TErrestrial RElations Observatory (STEREO) heliospheric imager (HI) observations, a new elliptic conversion (ElCon) method is introduced and combined with the use of drag-based model (DBM) fitting to quantify the deceleration or acceleration experienced by CMEs during propagation. The result is then used as input for the Ellipse Evolution Model (ElEvo). Together, ElCon, DBM fitting, and ElEvo form the novel ElEvoHI forecasting utility. To demonstrate the applicability of ElEvoHI, we forecast the arrival times and speeds of 21 CMEs remotely observed from STEREO/HI and compare them to in situ arrival times and speeds at 1 AU. Compared to the commonly used STEREO/HI fitting techniques (Fixed-ϕ, Harmonic Mean, and Self-similar Expansion fitting), ElEvoHI improves the arrival time forecast by about 2 to ±6.5 hr and the arrival speed forecast by ≈ 250 to ±53 km s-1, depending on the ellipse aspect ratio assumed. In particular, the remarkable improvement of the arrival speed prediction is potentially beneficial for predicting geomagnetic storm strength at Earth. Title: Deriving CME kinematics from multipoint space observations Authors: Mrotzek, Niclas; Pluta, Adam; Bothmer, Volker; Davies, Jackie; Harrison, Richard Bibcode: 2016EGUGA..18.8058M Altcode: It is commonly believed that the kinematics of CMEs consist of an early Lorentz acceleration phase near the Sun followed by a decelerating drag-force phase at distances further out. To better understand the physical processes of CME evolution, and also to predict more accurately their arrival times at other heliospheric locations, we have analysed CMEs using multipoint coronagraph observations from STEREO and SOHO. The CME speed evolution is analysed by applying time-series GCS-modelling. The analysis is extended to distances further away from the Sun through analysis of observations from the STEREO heliospheric imagers. The results are compared to those obtained from the geometrical modelling of time-elongation profiles of CMEs extracted from J-maps. We discuss the implications of our results in the context of state-of-the-art space weather predictions. The studies are carried out in the EU FP7 project HELCATS (Heliospheric Cataloguing, Analysis and Techniques Service). Title: ElEvoHI - Improving CME arrival predictions using heliospheric imaging Authors: Rollett, Tanja; Möstl, Christian; Isavnin, Alexey; Kubicka, Manuel; Amerstorfer, Ute; Davies, Jackie; Harrison, Richard Bibcode: 2016EGUGA..18.7309R Altcode: The STEREO mission has sampled a tremendous amount of data, which have served as a basis to develop a lot of new methods to analyze the dynamics of coronal mass ejections (CMEs) during their journey through interplanetary space. The STEREO heliospheric imagers (HI) in particular are unsurpassed in their contribution to a deeper understanding of how CMEs are influenced by interaction with the solar wind and other CMEs and how they evolve in the inner heliosphere. Although STEREO is currently not well observing the space between the Sun and Earth, the large data repository of HI observations enables us to further improve the prediction of CME arrival times and speeds using HI observations - particularly with regard to a potential future L5 mission. We present a new method for predicting arrival times and speeds of CMEs at any location in the inner heliosphere: ElEvoHI. This new approach uses HI observations as input and assumes an elliptic CME front shape. The solar wind influence is taken into account by fitting the observations using the drag-based model. In this way, it is possible to gain all parameters needed as input for the Ellipse Evolution model (ElEvo), which is then used to predict the CME arrival. To demonstrate the applicability of ElEvoHI we present the forecasts for 20 CMEs remotely observed by STEREO/HI and compare the forecasts to their in situ arrival times and speeds at 1 AU. Compared to the widely used Fixed-φ fitting method, ElEvoHI improves the arrival time forecast by 2.2 hours to ±6.5 hours and the arrival speed forecast by 260 km s-1 to ±55 km s-1. In particular, the remarkable improvement of the arrival speed prediction is crucial for predicting geomagnetic storm strength on Earth. Title: HELCATS - Heliospheric Cataloguing, Analysis and Techniques Service Authors: Harrison, Richard; Davies, Jackie; Perry, Chris; Moestl, Christian; Rouillard, Alexis; Bothmer, Volker; Rodriguez, Luciano; Eastwood, Jonathan; Kilpua, Emilia; Gallagher, Peter Bibcode: 2016EGUGA..1810220H Altcode: Understanding the evolution of the solar wind is fundamental to advancing our knowledge of energy and mass transport in the solar system, rendering it crucial to space weather and its prediction. The advent of truly wide-angle heliospheric imaging has revolutionised the study of both transient (CMEs) and background (SIRs/CIRs) solar wind plasma structures, by enabling their direct and continuous observation out to 1 AU and beyond. The EU-funded FP7 HELCATS project combines European expertise in heliospheric imaging, built up in particular through lead involvement in NASA's STEREO mission, with expertise in solar and coronal imaging as well as in-situ and radio measurements of solar wind phenomena, in a programme of work that will enable a much wider exploitation and understanding of heliospheric imaging observations. With HELCATS, we are (1.) cataloguing transient and background solar wind structures imaged in the heliosphere by STEREO/HI, since launch in late October 2006 to date, including estimates of their kinematic properties based on a variety of established techniques and more speculative, approaches; (2.) evaluating these kinematic properties, and thereby the validity of these techniques, through comparison with solar source observations and in-situ measurements made at multiple points throughout the heliosphere; (3.) appraising the potential for initialising advanced numerical models based on these kinematic properties; (4.) assessing the complementarity of radio observations (in particular of Type II radio bursts and interplanetary scintillation) in combination with heliospheric imagery. We will, in this presentation, provide an overview of progress from the first 18 months of the HELCATS project. Title: First Results on Visualization and Verification of the STEREO Heliospheric Imager CME Catalogue with In Situ Data from the Heliophysics System Observatory Authors: Rollett, T.; Moestl, C.; Boakes, P. D.; Isavnin, A.; Davies, J. A.; Byrne, J.; Barnes, D.; Good, S. W.; Perry, C. H.; Kubicka, M.; Harrison, R. A.; Kilpua, E.; Forsyth, R. J.; Bothmer, V. Bibcode: 2015AGUFMSH53A2466R Altcode: The space weather community has recently seen major advances in the prediction of the speed and arrival time of solar coronal mass ejections at Earth and other planets. Since the start of the STEREO mission in 2006, each of the heliospheric imagers (HIs) onboard the Ahead and Behind spacecraft has successfully tracked hundreds of CMEs. The advantage of HI is that CMEs can be followed for a significant part of the inner heliosphere, and the CME evolution in direction and speed is better constrained than by coronagraphs alone. By tracking and cataloguing each of those CMEs in the EU HELCATS project, we can apply geometrical modeling (FPF, HMF, SSEF) techniques on single-spacecraft HI observations to extract the expected planetary impacts of each CME. These arrivals are then verified or refuted by in situ solar wind plasma and magnetic field observations provided by the spacecraft forming the Heliophysics System Observatory (HSO), such as Wind, ACE, Venus Express, MESSENGER, and STEREO-A/B, for which various ICME catalogues are gathered and updated in the course of HELCATS.A first assessment on the relationship between CME HI and in situ observations is discussed, such as occurrence rates, speeds and arrival times and magnetic field strength. We also present visualizations of the HI CME catalogue and the corresponding in situ observations. The presented work has received funding from the European Union Seventh Framework Programme (FP7/ 2007-2013) under grant agreement No. 606692 [HELCATS]. Title: HELCATS - Heliospheric Cataloguing, Analysis and Techniques Service Authors: Barnes, D.; Harrison, R. A.; Davies, J. A.; Byrne, J.; Perry, C. H.; Moestl, C.; Rouillard, A. P.; Bothmer, V.; Rodriguez, L.; Eastwood, J. P.; Kilpua, E.; Odstrcil, D.; Gallagher, P. Bibcode: 2015AGUFMSH21B2410B Altcode: Understanding the evolution of the solar wind is fundamental to advancing our knowledge of energy and mass transport in the Solar System, making it crucial to space weather and its prediction. The advent of truly wide-angle heliospheric imaging has revolutionised the study of both transient (CMEs) and background (IRs) solar wind plasma structures, by enabling their direct and continuous observation out to 1 AU and beyond. The EU-funded FP7 HELCATS project combines European expertise in heliospheric imaging, built up in particular through lead involvement in NASA's STEREO mission, with expertise in solar and coronal imaging as well as in-situ and radio measurements of solar wind phenomena, in a programme of work that will enable a much wider exploitation and understanding of heliospheric imaging observations. The HELCATS project endeavors to catalogue transient and background solar wind structures imaged by STEREO/HI throughout the duration of the mission. This catalogue will include estimates of their kinematic properties using a variety of established and more speculative approaches, which are to be evaluated through comparisons with solar source and in-situ measurements. The potential for driving numerical models from these kinematic properties is to be assessed, as is their complementarity to radio observations, specifically Type II bursts and interplanetary scintillation. This presentation provides an overview of the HELCATS project and its progress in first 18 months of operations. Title: Requirements for an Operational Coronagraph Authors: Howard, R.; Vourlidas, A.; Harrison, R. A.; Bisi, M. M.; Plunkett, S. P.; Socker, D. G.; Eyles, C. J.; Webb, D. F.; DeForest, C. E.; Davies, J. A.; Howard, T. A.; de Koning, C. A.; Gopalswamy, N.; Davila, J. M.; Tappin, J.; Jackson, B. V. Bibcode: 2015AGUFMSH14A..02H Altcode: Coronal mass ejections (CMEs) have been shown to be the major driver of the non-recurrent space weather events and geomagnetic storms. The utility of continuously monitoring such events has been very effectively demonstrated by the LASCO experiment on the SOHO mission. However SOHO is aging, having been launched 20 years ago on Dec 2, 1995. The STEREO mission, in which two spacecraft in orbits about the sun are drifting away from earth, has shown the utility of multiple viewpoints off the sun-earth line. Up to now the monitoring of CMES has been performed by scientific instruments such as LASCO and SECCHI with capabilities beyond those required to record the parameters that are needed to forecast the impact at earth. However, there is great interest within the US NOAA and the UK Met Office to launch operational coronagraphs to L1 and L5. An ad-hoc group was formed to define the requirements of the L5 coronagraph. In this paper we present some requirements that must be met by operational coronagraphs. The Office of Naval Research is gratefully acknowledged. Title: Coronal and heliospheric imagers for solar wind phenomena Authors: Middleton, Kevin F.; Bourdelle, Anthony; Davies, Jackie A.; Eyles, Chris J.; Griffin, Doug K.; Harrison, Richard A.; Richards, Tony R.; Rogers, J. Kevin; Tappin, S. James; Tosh, Ian A. J.; Waltham, Nick R. Bibcode: 2015SPIE.9604E..0RM Altcode: RAL Space is enhancing its program to lead the development of European capabilities in space-based visible-light coronal and heliospheric imaging instrumentation in the light of emerging opportunities such as the European Space Agency's Space Situational Awareness program and recent S2 small-mission call. Visible-light coronal and heliospheric imaging of solar wind phenomena, such as coronal mass ejections and interaction regions, is of critical importance to space weather studies, both operationally and in terms of enabling the underpinning science. This work draws on heritage from scientific instruments such as LASCO (Large Angle and Spectrometric Coronagraph) on the SOHO spacecraft, SMEI (Solar Mass Ejection Imager) on the Coriolis spacecraft and the HI (Heliospheric Imager) instruments on STEREO. Such visible-light observation of solar wind structures relies on the detection of sunlight that has been Thomson-scattered by electrons (the so-called K-corona). The Thomson-scattered signal must be extracted from other signals that can be many orders of magnitude greater (such as that from the F-corona and the solar disc itself) and this places stringent constraints on stray-light rejection, as well as pointing stability and accuracy. We discuss the determination of instrument requirements, key design trade-offs and the evolution of base-line designs for the coronal and heliospheric regimes. We explain how the next generation of instruments will build on this heritage while also, in some cases, meeting the challenges on resources imposed on operational space weather imagers. In particular, we discuss the optical engineering challenges involved in the design of these instruments. Title: Carrington-L5: The UK/US Operational Space Weather Monitoring Mission Authors: Trichas, Markos; Gibbs, Mark; Harrison, Richard; Green, Lucie; Eastwood, Jonathan; Bentley, Bob; Bisi, Mario; Bogdanova, Yulia; Davies, Jackie; D'Arrigo, Paolo; Eyles, Chris; Fazakerley, Andrew; Hapgood, Mike; Jackson, David; Kataria, Dhiren; Monchieri, Emanuele; Windred, Phil Bibcode: 2015Hipp....2l..25T Altcode: 2015Hipp....2...25T Airbus Defence and Space (UK) has carried out a study to investigate the possibilities for an operational space weather mission, in collaboration with the Met Office, RAL, MSSL and Imperial College London. The study looked at the user requirements for an operational mission, a model instrument payload, and a mission/spacecraft concept. A particular focus is cost effectiveness and timelineness of the data, suitable for 24/7 operational forecasting needs. We have focussed on a mission at L5 assuming that a mission to L1 will already occur, on the basis that L5 (Earth trailing) offers the greatest benefit for the earliest possible warning on hazardous SWE events and the most accurate SWE predictions. The baseline payload has been selected to cover all UK Met Office/NOAA's users priorities for L5 using instruments with extensive UK/US heritage, consisting of: heliospheric imager, coronograph, magnetograph, magnetometer, solar wind analyser and radiation monitor. The platform and subsystems are based on extensive re-use from past Airbus Defence and Space spacecraft to minimize the development cost and a Falcon-9 launcher has been selected on the same basis. A schedule analysis shows that the earliest launch could be achieved by 2020, assuming Phase A kick-off in 2015-2016. The study team have selected the name "Carrington" for the mission, reflecting the UK's proud history in this domain. Title: Radio Flares from Gamma-ray Bursts Authors: Kopač, D.; Mundell, C. G.; Kobayashi, S.; Virgili, F. J.; Harrison, R.; Japelj, J.; Guidorzi, C.; Melandri, A.; Gomboc, A. Bibcode: 2015ApJ...806..179K Altcode: 2015arXiv150308428K We present predictions of centimeter and millimeter radio emission from reverse shocks (RSs) in the early afterglows of gamma-ray bursts (GRBs) with the goal of determining their detectability with current and future radio facilities. Using a range of GRB properties, such as peak optical brightness and time, isotropic equivalent gamma-ray energy, and redshift, we simulate radio light curves in a framework generalized for any circumburst medium structure and including a parameterization of the shell thickness regime that is more realistic than the simple assumption of thick- or thin-shell approximations. Building on earlier work by Mundell et al. and Melandri et al. in which the typical frequency of the RS was suggested to lie at radio rather than optical wavelengths at early times, we show that the brightest and most distinct RS radio signatures are detectable up to 0.1-1 day after the burst, emphasizing the need for rapid radio follow-up. Detection is easier for bursts with later optical peaks, high isotropic energies, lower circumburst medium densities, and at observing frequencies that are less prone to synchrotron self-absorption effects—typically above a few GHz. Given recent detections of polarized prompt gamma-ray and optical RS emission, we suggest that detection of polarized radio/millimeter emission will unambiguously confirm the presence of low-frequency RSs at early time. Title: Long-lived magnetism from inner core solidification on small planetary bodies Authors: Bryson, James; Nichols, Claire; Herrero Albillos, Julia; Kronast, Florian; Kasama, Takeshi; Alimadadi, Hossein; van der Laan, Gerrit; Nimmo, Francis; Harrison, Richard Bibcode: 2015EGUGA..17.3756B Altcode: Paleomagnetic measurements of meteorites suggest that many asteroids generated their own magnetic activity during the early solar system, with the majority of measured meteorite classes appearing to have recorded dynamo fields. Despite this apparent near ubiquity of magnetic activity among small planetary bodies, many of the most fundamental aspects of this activity remain enigmatic. Crucially, both the temporal evolution and the processes capable of generating small body magnetic activity are yet to be gleaned from paleomagnetic measurements. This information has been central in understanding the dynamic and thermochemical evolution of our planet, and equivalent information from asteroids could help illuminate the evolution of matter in our solar system. Here, we present time-resolved records of the magnetic activity generated on the main-group pallasite parent body inferred from X-ray photoemission electron microscopy (XPEEM) images of the metal matrix within the Imilac, Esquel, Brenham and Marjalahti pallasite meteorites. This metal cooled at <10 K/Myr, which permitted a unique nanostructure known as the cloudy zone (CZ) to form. The CZ is an excellent paleomagnetic recorder, and formed over a distance of ~10 µm over tens of millions of years. By spatially resolving the magnetism of this nanostructure using XPEEM, we infer both the direction and intensity of the field experienced by the CZ of these meteorites. All four meteorites recorded unidirectional fields. The Brenham and Marjalahti meteorites recorded relatively weak fields with intensities of >20 µT over a period of ~4 - 10 Myr. The Imilac meteorite recorded a stronger field between 120 - 130 µT over a period of <10 Myr. The Esquel meteorite initially recorded a field of ~80 µT, which then weakened over time down to a plateau at ~30 µT, before decreasing further down to ~0 µT. By comparing experimental cooling rates to those predicted from planetary cooling models, the Brenham and Marjalahti meteorites are expected to have recorded the magnetic activity shortly before core solidification, and the Imilac and Esquel meteorites are expected to have recorded the magnetic activity associated with the early and later stages of this process, respectively. Dynamo field intensities predicted from empirical scaling relationships suggest that the Imilac meteorite experienced a dipolar dynamo field generated by compositional convection associated with the early stages of bottom-up core solidification. The Esquel meteorite appears to have experienced a dipolar-multipolar transition (intensity decrease), multipolar regime (plateau at ~30 µT), and the cessation of dynamo activity associated with the near-completion of core solidification (decrease down to ~0 µT). The weak fields experienced by the Brenham and Marjalahti are consistent with a period of dynamo activity quiescence prior to inner core growth. Solidification-driven convection is yet to be associated with small bodies, but given its efficiency, likely lead to convection across the majority of bottom-up solidifying cores in these bodies, implying a widespread, intense and long-lived epoch of magnetic activity among small bodies during the early solar system. Title: HELCATS Prediction of Planetary CME arrival times Authors: Boakes, Peter; Moestl, Christian; Davies, Jackie; Harrison, Richard; Byrne, Jason; Barnes, David; Isavnin, Alexey; Kilpua, Emilia; Rollett, Tanja Bibcode: 2015EGUGA..17.3601B Altcode: We present the first results of CME arrival time prediction at different planetary locations and their comparison to the in situ data within the HELCATS project. The EU FP7 HELCATS (Heliospheric Cataloguing, Analysis & Techniques Service) is a European effort to consolidate the exploitation of the maturing field of heliospheric imaging. HELCATS aims to catalogue solar wind transients, observed by the NASA STEREO Heliospheric Imager (HI) instruments, and validate different methods for the determination of their kinematic properties. This validation includes comparison with arrivals at Earth, and elsewhere in the heliosphere, as well as onsets at the Sun (http://www.helcats-fp7.eu/). A preliminary catalogue of manually identified CMEs, with over 1000 separate events, has been created from observations made by the STEREO/HI instruments covering the years 2007-2013. Initial speeds and directions of each CME have been derived through fitting the time elongation profile to the state of the art Self-Similar Expansion Fitting (SSEF) geometric technique (Davies et al., 2012). The technique assumes that, in the plane corresponding to the position angle of interest, CMEs can be modelled as circles subtending a fixed angular width to Sun-center and propagating anti-sunward in a fixed direction at a constant speed (we use an angular width of 30 degrees in our initial results). The model has advantages over previous geometric models (e.g. harmonic mean or fixed phi) as it allows one to predict whether a CME will 'hit' a specific heliospheric location, as well as to what degree (e.g. direct assault or glancing blow). We use correction formulae (Möstl and Davies, 2013) to convert CME speeds, direction and launch time to speed and arrival time at any in situ location. From the preliminary CME dataset, we derive arrival times for over 400 Earth-directed CMEs, and for over 100 Mercury-, Venus-, Mars- and Saturn-directed CMEs predicted to impact each planet. We present statistics of predicted CME arrival properties. In addition, we independently identify CME arrival at in situ locations using magnetic field data from the Venus Express, Messenger, and Ulysses spacecraft and show first comparisons to predicted arrival times. The results hold important implications for space weather prediction at Earth and other locations, allowing model and predicted CME parameters to be compared to their in situ counterparts. 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: The HELCATS Project: Characterising the Evolution of Coronal Mass Ejections Observed During Solar Cycle 24 Authors: Bisi, M. M.; Harrison, R. A.; Davies, J. A.; Perry, C. H.; Moestl, C.; Rouillard, A. P.; Bothmer, V.; Rodriguez, L.; Eastwood, J. P.; Kilpua, E.; Gallagher, P.; Odstrcil, D. Bibcode: 2014AGUFMSH43B4214B Altcode: Understanding the evolution of coronal mass ejections (CMEs) is fundamental to advancing our knowledge of energy and mass transport in the solar system, thus also rendering it crucial to space weather and its prediction. The advent of truly wide-angle heliospheric imaging has revolutionised the study of CMEs, by enabling their direct and continuous observation as they propagate from the Sun out to 1 AU and beyond. The recently initiated EU-funded FP7 Heliospheric Cataloguing, Analysis and Technique Service (HELCATS) project combines European expertise in the field of heliospheric imaging, built up over the last decade in particular through lead involvement in NASA's STEREO mission, with expertise in such areas as solar and coronal imaging as well as the interpretation of in-situ and radio diagnostic measurements of solar wind phenomena. The goals of HELCATS include the cataloguing of CMEs observed in the heliosphere by the Heliospheric Imager (HI) instruments on the STEREO spacecraft, since their launch in late October 2006 to date, an interval that covers much of the historically weak solar cycle 24. Included in the catalogue will be estimates of the kinematic properties of the imaged CMEs, based on a variety of established, and some more speculative, modelling approaches (geometrical, forward, inverse, magneto-hydrodynamic); these kinematic properties will be verified through comparison with solar disc and coronal imaging observations, as well as through comparison with radio diagnostic and in-situ measurements made at multiple points throughout the heliosphere. We will provide an overview of the HELCATS project, and present initial results that will seek to illuminate the unusual nature of solar cycle 24. Title: Connecting Speeds, Directions and Arrival Times of 22 Coronal Mass Ejections from the Sun to 1 AU Authors: Möstl, C.; Amla, K.; Hall, J. R.; Liewer, P. C.; De Jong, E. M.; Colaninno, R. C.; Veronig, A. M.; Rollett, T.; Temmer, M.; Peinhart, V.; Davies, J. A.; Lugaz, N.; Liu, Y. D.; Farrugia, C. J.; Luhmann, J. G.; Vršnak, B.; Harrison, R. A.; Galvin, A. B. Bibcode: 2014ApJ...787..119M Altcode: 2014arXiv1404.3579M Forecasting the in situ properties of coronal mass ejections (CMEs) from remote images is expected to strongly enhance predictions of space weather and is of general interest for studying the interaction of CMEs with planetary environments. We study the feasibility of using a single heliospheric imager (HI) instrument, imaging the solar wind density from the Sun to 1 AU, for connecting remote images to in situ observations of CMEs. We compare the predictions of speed and arrival time for 22 CMEs (in 2008-2012) to the corresponding interplanetary coronal mass ejection (ICME) parameters at in situ observatories (STEREO PLASTIC/IMPACT, Wind SWE/MFI). The list consists of front- and backsided, slow and fast CMEs (up to 2700 km s-1). We track the CMEs to 34.9 ± 7.1 deg elongation from the Sun with J maps constructed using the SATPLOT tool, resulting in prediction lead times of -26.4 ± 15.3 hr. The geometrical models we use assume different CME front shapes (fixed-Φ, harmonic mean, self-similar expansion) and constant CME speed and direction. We find no significant superiority in the predictive capability of any of the three methods. The absolute difference between predicted and observed ICME arrival times is 8.1 ± 6.3 hr (rms value of 10.9 hr). Speeds are consistent to within 284 ± 288 km s-1. Empirical corrections to the predictions enhance their performance for the arrival times to 6.1 ± 5.0 hr (rms value of 7.9 hr), and for the speeds to 53 ± 50 km s-1. These results are important for Solar Orbiter and a space weather mission positioned away from the Sun-Earth line. Title: Connecting speeds, directions and arrival times of 22 coronal mass ejections from the Sun to 1 AU Authors: Möstl, Christian; Amla, Keshav; Hall, Jeff R.; Liewer, Paulett C.; DeJong, Eric M.; Colaninno, Robin C.; Veronig, Astrid M.; Rollett, Tanja; Temmer, Manuela; Peinhart, Vanessa; Davies, Jackie A.; Lugaz, Noé; Liu, Ying; Farrugia, Charles J.; Luhmann, Janet G.; Vrsnak, Bojan; Harrison, Richard A.; Galvin, Antoinette B. Bibcode: 2014EGUGA..16.1755M Altcode: Forecasting in situ properties of coronal mass ejections (CMEs) from remote images is expected to strongly enhance predictions of space weather, and is of general interest for studying the interaction of the solar wind with planetary environments. We study the feasibility of using a heliospheric imager (HI) instrument, which is able to image the solar wind density along the full Sun to 1 AU distance, for connecting remote images to in situ observations of CMEs. Such an instrument is currently in operation on each of the two STEREO spacecraft. We compare the predictions for speed and arrival time for 22 different CME events (between 2008-2012), each observed remotely by one STEREO spacecraft, to the interplanetary coronal mass ejection (ICME) speed and arrival time observed at in situ observatories (STEREO PLASTIC/IMPACT, Wind SWE/MFI). We use croissant modeling for STEREO/COR2, and with a single-spacecraft STEREO/HI instrument, we track each CME to 34.9 ± 7.1 degree elongation from the Sun with J-maps constructed with the SATPLOT tool. We then fit geometrical models to each track, assuming different CME front shapes (Fixed-Φ, Harmonic Mean, Self-Similar Expansion), and constant CME speed and direction. We find no significant preference in the predictive capability for any of the three geometrical modeling methods used on the full event list, consisting of front- and backsided, slow and fast CMEs (up to 2700 km s-1). The absolute difference between predicted and observed ICME arrival times is 8.1 ± 6.4 hours (rms value of 10.9h), and speeds are consistent within 284 ± 291 km s-1, including the geometric effects of CME apex or flank encounters. We derive new empirical corrections to the imaging results, enhancing the performance of the arrival time predictions to 6.1 ± 5.0 hours (rms value of 7.9h), and the speed predictions to 53 ± 50 km s-1, for this particular set of events. The prediction lead time is around 1 day (-26.4 ± 15.3h). CME directions given by the HI methods differ considerably, and biases are found on the order of 30-50 degree in heliospheric longitude, consistent with theoretical expectations. These results are of interest concerning future missions such as Solar Orbiter or a dedicated space weather mission positioned remotely from the Earth. Title: Phenomenology of Reverse-shock Emission in the Optical Afterglows of Gamma-Ray Bursts Authors: Japelj, J.; Kopač, D.; Kobayashi, S.; Harrison, R.; Guidorzi, C.; Virgili, F. J.; Mundell, C. G.; Melandri, A.; Gomboc, A. Bibcode: 2014ApJ...785...84J Altcode: 2014arXiv1402.3701J We use a parent sample of 118 gamma-ray burst (GRB) afterglows, with known redshift and host galaxy extinction, to separate afterglows with and without signatures of dominant reverse-shock (RS) emission and to determine which physical conditions lead to a prominent reverse-shock emission. We identify 10 GRBs with reverse-shock signatures: 990123, 021004, 021211, 060908, 061126, 080319B, 081007, 090102, 090424, and 130427A. By modeling their optical afterglows with reverse- and forward-shock analytic light curves and using Monte Carlo simulations, we estimate the parameter space of the physical quantities describing the ejecta and circumburst medium. We find that physical properties cover a wide parameter space and do not seem to cluster around any preferential values. Comparing the rest-frame optical, X-ray, and high-energy properties of the larger sample of non-RS-dominated GRBs, we show that the early-time (<1 ks) optical spectral luminosity, X-ray afterglow luminosity, and γ-ray energy output of our reverse-shock dominated sample do not differ significantly from the general population at early times. However, the GRBs with dominant reverse-shock emission have fainter than average optical forward-shock emission at late times (>10 ks). We find that GRBs with an identifiable reverse-shock component show a high magnetization parameter R B = ɛB, rB, f ~ 2-104. Our results are in agreement with the mildly magnetized baryonic jet model of GRBs. Title: New constraints on gamma-ray burst jet geometry and relativistic shock physics Authors: Guidorzi, C.; Mundell, C. G.; Harrison, R.; Margutti, R.; Sudilovsky, V.; Zauderer, B. A.; Kobayashi, S.; Cucchiara, A.; Melandri, A.; Pandey, S. B.; Berger, E.; Bersier, D.; D'Elia, V.; Gomboc, A.; Greiner, J.; Japelj, J.; Kopač, D.; Kumar, B.; Malesani, D.; Mottram, C. J.; O'Brien, P. T.; Rau, A.; Smith, R. J.; Steele, I. A.; Tanvir, N. R.; Virgili, F. Bibcode: 2014MNRAS.438..752G Altcode: 2013arXiv1311.4340G; 2013MNRAS.tmp.2902G We use high-quality, multiband observations of Swift GRB 120404A, from γ-ray to radio frequencies, together with the new hydrodynamics code of van Eerten et al. to test the standard synchrotron shock model. The evolution of the radio and optical afterglow, with its prominent optical rebrightening at trest ∼ 260-2600 s, is remarkably well modelled by a decelerating jet viewed close to the jet edge, combined with some early re-energization of the shock. We thus constrain the geometry of the jet with half-opening and viewing angles of 23° and 21°, respectively, and suggest that wide jets viewed off-axis are more common in GRBs than previously thought. We also derive the fireball microphysics parameters ɛB = 2.4 × 10-4 and ɛe = 9.3 × 10-2 and a circumburst density of n = 240 cm-3. The ability to self-consistently model the microphysics parameters and jet geometry in this way offers an alternative to trying to identify elusive canonical jet breaks at late times. The mismatch between the observed and model-predicted X-ray fluxes is explained by the local rather than the global cooling approximation in the synchrotron radiation model, constraining the microphysics of particle acceleration taking place in a relativistic shock and, in turn, emphasizing the need for a more realistic treatment of cooling in future developments of theoretical models. Finally, our interpretation of the optical peak as due to the passage of the forward shock synchrotron frequency highlights the importance of high-quality multiband data to prevent some optical peaks from being erroneously attributed to the onset of fireball deceleration. 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: GRB 130427A: A Nearby Ordinary Monster Authors: Maselli, A.; Melandri, A.; Nava, L.; Mundell, C. G.; Kawai, N.; Campana, S.; Covino, S.; Cummings, J. R.; Cusumano, G.; Evans, P. A.; Ghirlanda, G.; Ghisellini, G.; Guidorzi, C.; Kobayashi, S.; Kuin, P.; La Parola, V.; Mangano, V.; Oates, S.; Sakamoto, T.; Serino, M.; Virgili, F.; Zhang, B. -B.; Barthelmy, S.; Beardmore, A.; Bernardini, M. G.; Bersier, D.; Burrows, D.; Calderone, G.; Capalbi, M.; Chiang, J.; D'Avanzo, P.; D'Elia, V.; De Pasquale, M.; Fugazza, D.; Gehrels, N.; Gomboc, A.; Harrison, R.; Hanayama, H.; Japelj, J.; Kennea, J.; Kopac, D.; Kouveliotou, C.; Kuroda, D.; Levan, A.; Malesani, D.; Marshall, F.; Nousek, J.; O'Brien, P.; Osborne, J. P.; Pagani, C.; Page, K. L.; Page, M.; Perri, M.; Pritchard, T.; Romano, P.; Saito, Y.; Sbarufatti, B.; Salvaterra, R.; Steele, I.; Tanvir, N.; Vianello, G.; Weigand, B.; Wiersema, K.; Yatsu, Y.; Yoshii, T.; Tagliaferri, G. Bibcode: 2014Sci...343...48M Altcode: 2013arXiv1311.5254M Long-duration gamma-ray bursts (GRBs) are an extremely rare outcome of the collapse of massive stars and are typically found in the distant universe. Because of its intrinsic luminosity (L ∼ 3 × 1053 ergs per second) and its relative proximity (z = 0.34), GRB 130427A reached the highest fluence observed in the γ-ray band. Here, we present a comprehensive multiwavelength view of GRB 130427A with Swift, the 2-meter Liverpool and Faulkes telescopes, and by other ground-based facilities, highlighting the evolution of the burst emission from the prompt to the afterglow phase. The properties of GRB 130427A are similar to those of the most luminous, high-redshift GRBs, suggesting that a common central engine is responsible for producing GRBs in both the contemporary and the early universe and over the full range of GRB isotropic energies. Title: Magnetic Field Structure in Relativistic Jets Authors: Jermak, Helen; Mundell, Carole; Steele, Iain; Harrison, Richard; Kobayashi, Shiho; Lindfors, Elina; Nilsson, Kari; Barres de Almeida, Ulisses Bibcode: 2013EPJWC..6103005J Altcode: Relativistic jets are ubiquitous when considering an accreting black hole. Two of the most extreme examples of these systems are blazars and gamma-ray bursts (GRBs), the jets of which are thought to be threaded with a magnetic field of unknown structure. The systems are made up of a black hole accreting matter and producing, as a result, relativistic jets of plasma from the poles of the black hole. Both systems are viewed as point sources from Earth, making it impossible to spatially resolve the jet. In order to explore the structure of the magnetic field within the jet we take polarisation measurements with the RINGO polarimeters on the world's largest fully autonomous, robotic optical telescope: The Liverpool Telescope. Using the polarisation degree and angle measured by the RINGO polarimeters it is possible to distinguish between global magnetic fields created in the central engine and random tangled magnetic fields produced locally in shocks. We also monitor blazar sources regularly during quiescence with periods of flaring monitored more intensively. Reported here are the early polarisation results for GRBs 060418 and 090102, along with future prospects for the Liverpool Telescope and the RINGO polarimeters. Title: GRB 091024A and the Nature of Ultra-long Gamma-Ray Bursts Authors: Virgili, F. J.; Mundell, C. G.; Pal'shin, V.; Guidorzi, C.; Margutti, R.; Melandri, A.; Harrison, R.; Kobayashi, S.; Chornock, R.; Henden, A.; Updike, A. C.; Cenko, S. B.; Tanvir, N. R.; Steele, I. A.; Cucchiara, A.; Gomboc, A.; Levan, A.; Cano, Z.; Mottram, C. J.; Clay, N. R.; Bersier, D.; Kopač, D.; Japelj, J.; Filippenko, A. V.; Li, W.; Svinkin, D.; Golenetskii, S.; Hartmann, D. H.; Milne, P. A.; Williams, G.; O'Brien, P. T.; Fox, D. B.; Berger, E. Bibcode: 2013ApJ...778...54V Altcode: 2013arXiv1310.0313V We present a broadband study of gamma-ray burst (GRB) 091024A within the context of other ultra-long-duration GRBs. An unusually long burst detected by Konus-Wind (KW), Swift, and Fermi, GRB 091024A has prompt emission episodes covering ~1300 s, accompanied by bright and highly structured optical emission captured by various rapid-response facilities, including the 2 m autonomous robotic Faulkes North and Liverpool Telescopes, KAIT, S-LOTIS, and the Sonoita Research Observatory. We also observed the burst with 8 and 10 m class telescopes and determine the redshift to be z = 1.0924 ± 0.0004. We find no correlation between the optical and γ-ray peaks and interpret the optical light curve as being of external origin, caused by the reverse and forward shock of a highly magnetized jet (RB ≈ 100-200). Low-level emission is detected throughout the near-background quiescent period between the first two emission episodes of the KW data, suggesting continued central-engine activity; we discuss the implications of this ongoing emission and its impact on the afterglow evolution and predictions. We summarize the varied sample of historical GRBs with exceptionally long durations in gamma-rays (gsim1000 s) and discuss the likelihood of these events being from a separate population; we suggest ultra-long GRBs represent the tail of the duration distribution of the long GRB population. Title: Establishing a Stereoscopic Technique for Determining the Kinematic Properties of Solar Wind Transients based on a Generalized Self-similarly Expanding Circular Geometry Authors: Davies, J. A.; Perry, C. H.; Trines, R. M. G. M.; Harrison, R. A.; Lugaz, N.; Möstl, C.; Liu, Y. D.; Steed, K. Bibcode: 2013ApJ...777..167D Altcode: The twin-spacecraft STEREO mission has enabled simultaneous white-light imaging of the solar corona and inner heliosphere from multiple vantage points. This has led to the development of numerous stereoscopic techniques to investigate the three-dimensional structure and kinematics of solar wind transients such as coronal mass ejections (CMEs). Two such methods—triangulation and the tangent to a sphere—can be used to determine time profiles of the propagation direction and radial distance (and thereby radial speed) of a solar wind transient as it travels through the inner heliosphere, based on its time-elongation profile viewed by two observers. These techniques are founded on the assumption that the transient can be characterized as a point source (fixed phi, FP, approximation) or a circle attached to Sun-center (harmonic mean, HM, approximation), respectively. These geometries constitute extreme descriptions of solar wind transients, in terms of their cross-sectional extent. Here, we present the stereoscopic expressions necessary to derive propagation direction and radial distance/speed profiles of such transients based on the more generalized self-similar expansion (SSE) geometry, for which the FP and HM geometries form the limiting cases; our implementation of these equations is termed the stereoscopic SSE method. We apply the technique to two Earth-directed CMEs from different phases of the STEREO mission, the well-studied event of 2008 December and a more recent event from 2012 March. The latter CME was fast, with an initial speed exceeding 2000 km s-1, and highly geoeffective, in stark contrast to the slow and ineffectual 2008 December CME. Title: Using Coordinated Observations in Polarized White Light and Faraday Rotation to Probe the Spatial Position and Magnetic Field of an Interplanetary Sheath Authors: Xiong, Ming; Davies, Jackie A.; Feng, Xueshang; Owens, Mathew J.; Harrison, Richard A.; Davis, Chris J.; Liu, Ying D. Bibcode: 2013ApJ...777...32X Altcode: 2013arXiv1308.3376X Coronal mass ejections (CMEs) can be continuously tracked through a large portion of the inner heliosphere by direct imaging in visible and radio wavebands. White light (WL) signatures of solar wind transients, such as CMEs, result from Thomson scattering of sunlight by free electrons and therefore depend on both viewing geometry and electron density. The Faraday rotation (FR) of radio waves from extragalactic pulsars and quasars, which arises due to the presence of such solar wind features, depends on the line-of-sight magnetic field component B and the electron density. To understand coordinated WL and FR observations of CMEs, we perform forward magnetohydrodynamic modeling of an Earth-directed shock and synthesize the signatures that would be remotely sensed at a number of widely distributed vantage points in the inner heliosphere. Removal of the background solar wind contribution reveals the shock-associated enhancements in WL and FR. While the efficiency of Thomson scattering depends on scattering angle, WL radiance I decreases with heliocentric distance r roughly according to the expression Ivpropr -3. The sheath region downstream of the Earth-directed shock is well viewed from the L4 and L5 Lagrangian points, demonstrating the benefits of these points in terms of space weather forecasting. The spatial position of the main scattering site r sheath and the mass of plasma at that position M sheath can be inferred from the polarization of the shock-associated enhancement in WL radiance. From the FR measurements, the local B ∥sheath at r sheath can then be estimated. Simultaneous observations in polarized WL and FR can not only be used to detect CMEs, but also to diagnose their plasma and magnetic field properties. Title: Magnetization Degree of Gamma-Ray Burst Fireballs: Numerical Study Authors: Harrison, Richard; Kobayashi, Shiho Bibcode: 2013ApJ...772..101H Altcode: 2012arXiv1211.1032H The relative strength between forward and reverse shock emission in early gamma-ray burst (GRB) afterglow reflects that of magnetic energy densities in the two shock regions. We numerically show that with the current standard treatment, the fireball magnetization is underestimated by up to two orders of magnitude. This discrepancy is especially large in the sub-relativistic reverse shock regime (i.e., the thin shell and intermediate regime), where most optical flashes were detected. We provide new analytic estimates of the reverse shock emission based on a better shock approximation, which well describe numerical results in the intermediate regime. We show that the reverse shock temperature at the onset of afterglow is constant, (\bar{\Gamma }_d-1)\sim 8\times 10^{-2}, when the dimensionless parameter ξ0 is more than several. Our approach is applied to case studies of GRB 990123 and 090102, and we find that magnetic fields in the fireballs are even stronger than previously believed. However, these events are still likely to be due to a baryonic jet with σ ~ 10-3 for GRB 990123 and ~3 × 10-4 to 3 for GRB 090102. Title: Observations and Modelling of the Inner Heliosphere: Preface and Tribute to the Late Dr. Andy Breen Authors: Bisi, M. M.; Harrison, R. A.; Lugaz, N.; van Driel-Gesztelyi, L.; Mandrini, C. H. Bibcode: 2013SoPh..285....1B Altcode: No abstract at ADS Title: Observations of Rapid Velocity Variations in the Slow Solar Wind Authors: Hardwick, S. A.; Bisi, M. M.; Davies, J. A.; Breen, A. R.; Fallows, R. A.; Harrison, R. A.; Davis, C. J. Bibcode: 2013SoPh..285..111H Altcode: The technique of interplanetary scintillation (IPS) is the observation of rapid fluctuations of the radio signal from an astronomical compact source as the signal passes through the ever-changing density of the solar wind. Cross-correlation of simultaneous observations of IPS from a single radio source, received at multiple sites of the European Incoherent SCATter (EISCAT) radio antenna network, is used to determine the velocity of the solar wind material passing over the lines of sight of the antennas. Calculated velocities reveal the slow solar wind to contain rapid velocity variations when viewed on a time-scale of several minutes. Solar TErrestrial RElations Observatory (STEREO) Heliospheric Imager (HI) observations of white-light intensity have been compared with EISCAT observations of IPS to identify common density structures that may relate to the rapid velocity variations in the slow solar wind. Title: Heliospheric Imaging of 3D Density Structures During the Multiple Coronal Mass Ejections of Late July to Early August 2010 Authors: Webb, D. F.; Möstl, C.; Jackson, B. V.; Bisi, M. M.; Howard, T. A.; Mulligan, T.; Jensen, E. A.; Jian, L. K.; Davies, J. A.; de Koning, C. A.; Liu, Y.; Temmer, M.; Clover, J. M.; Farrugia, C. J.; Harrison, R. A.; Nitta, N.; Odstrcil, D.; Tappin, S. J.; Yu, H. -S. Bibcode: 2013SoPh..285..317W Altcode: It is usually difficult to gain a consistent global understanding of a coronal mass ejection (CME) eruption and its propagation when only near-Sun imagery and the local measurements derived from single-spacecraft observations are available. Three-dimensional (3D) density reconstructions based on heliospheric imaging allow us to "fill in" the temporal and spatial gaps between the near-Sun and in situ data to provide a truly global picture of the propagation and interactions of the CME as it moves through the inner heliosphere. In recent years the heliospheric propagation of dense structures has been observed and measured by the heliospheric imagers of the Solar Mass Ejection Imager (SMEI) and on the twin Solar TErrestrial RElations Observatory (STEREO) spacecraft. We describe the use of several 3D reconstruction techniques based on these heliospheric imaging data sets to distinguish and track the propagation of multiple CMEs in the inner heliosphere during the very active period of solar activity in late July - early August 2010. We employ 3D reconstruction techniques used at the University of California, San Diego (UCSD) based on a kinematic solar wind model, and also the empirical Tappin-Howard model. We compare our results with those from other studies of this active period, in particular the heliospheric simulations made with the ENLIL model by Odstrcil et al. (J. Geophys. Res., 2013) and the in situ results from multiple spacecraft provided by Möstl et al. (Astrophys. J.758, 10 - 28, 2012). We find that the SMEI results in particular provide an overall context for the multiple-density flows associated with these CMEs. For the first time we are able to intercompare the 3D reconstructed densities with the timing and magnitude of in situ density structures at five spacecraft spread over 150° in ecliptic longitude and from 0.4 to 1 AU in radial distance. We also model the magnetic flux-rope structures at three spacecraft using both force-free and non-force-free modelling, and compare their timing and spatial structure with the reconstructed density flows. Title: Stealth Coronal Mass Ejections: A Perspective Authors: Howard, Timothy A.; Harrison, Richard A. Bibcode: 2013SoPh..285..269H Altcode: "Stealth CME" has become a commonly used term in recent studies of solar activity. It refers to a coronal mass ejection (CME) with no apparent solar surface association, and therefore has no easily identifiable signature to locate the region on the Sun from which the CME erupted. We review the literature and express caution in categorising CMEs in this way. CMEs were discovered some 40 years ago and there have been numerous statistical studies of associations with phenomena in the solar atmosphere which clearly identify a range of associations, from bright flares and large prominence eruptions to small flares, and even a lack of flares or any identifiable surface activity at all. In this sense the stealth CME concept is not new. One major question relates to whether the range of associations reveal different CME classes, i.e. different CME launch processes, or are indicative of a spectrum of coronal responses to one common process. We favour the latter and stress that this spectrum must be considered in the description of the CME launch, meaning that the physics of a so-called stealth CME must not be fundamentally different from a CME associated with major surface events. On the other hand we also stress that the use of a stealth CME category implies that all surface activity could indeed be detected using modern instrumentation. We argue that this may not be the case, and that even in the SDO era of full-Sun, high resolution imaging, we are restricted by instrument sensitivity and bandwidth issues. Thus, having reviewed the case for stealth CMEs as a distinct category, we stress the need to keep the concept in perspective. Title: A Critical Examination of the Fundamental Assumptions of Solar Flare and Coronal Mass Ejection Models Authors: Spicer, D. S.; Bingham, R.; Harrison, R. Bibcode: 2013ApJ...768....8S Altcode: The fundamental assumptions of conventional solar flare and coronal mass ejection (CME) theory are re-examined. In particular, the common theoretical assumption that magnetic energy that drives flares and CMEs can be stored in situ in the corona with sufficient energy density is found wanting. In addition, the observational constraint that flares and CMEs produce non-thermal electrons with fluxes of order 1034-1036 electrons s-1, with energies of order 10-20 keV, must also be explained. This constraint when imposed on the "standard model" for flares and CMEs is found to miss the mark by many orders of magnitude. We suggest, in conclusion, there are really only two possible ways to explain the requirements of observations and theory: flares and CMEs are caused by mass-loaded prominences or driven directly by emerging magnetized flux. Title: Multi-Technique Remote-Sensing Observations and Modelling of a Coronal Mass Ejection Authors: Hardwick, S. A.; Bisi, M. M.; Davies, J.; Morgan, H.; Fallows, R.; Harrison, R. A.; Xiong, M.; Jensen, E. A. Bibcode: 2012AGUFMSH41C2123H Altcode: On 14 November 2011, SDO|AIA observed a filament eruption located around S25 to S30 and extended between W20 and W40 of disc centre. The resulting coronal mass ejection (CME) is studied in detail using radio, white-light, and EUV remote-sensing observations from STEREO, SOHO, SDO, and the new next-generation LOFAR radio telescope system. We present a detailed story of the CME as it travels through the heliosphere with its northern flank travelling in the ecliptic out towards Mars. Various models are fitted to the heliospheric white-light data and different portions of the CME are investigated as they propagate through the inner heliosphere. The validity of each model is discussed. This combination of remote-sensing observational and modelling techniques displays a valid framework for further detailed investigations of CMEs. Title: Highlights in Remote-Sensing Observations of the Inner Heliosphere During 2011 and 2012 Focussing on the EISCAT and LOFAR Radio-Telescope Systems Authors: Bisi, M. M.; Fallows, R.; Hardwick, S. A.; Jensen, E. A.; Davies, J.; Harrison, R. A.; Xiong, M.; Wu, C. Bibcode: 2012AGUFMSH43A2138B Altcode: Significant progress has been made over the last two years on the implementation of, and science resulting from, radio remote-sensing observations of the inner heliosphere using the European Incoherent SCATter (EISCAT) radar and the LOw Frequency ARray (LOFAR) radio-telescope systems. LOFAR is a precursor to the Square Kilometre Array (SKA), the world's largest ever radio telescope system. Here, we highlight some of these advances in radio remote-sensing heliospheric science, and where appropriate, we show examples of comparative and joint studies with data from other remote-sensing observations as well as with modelling of the inner heliosphere. Data from 2011 and 2012 will provide the foci of this work, although historical comparisons may be necessary. EISCAT has been used for relatively-high-frequency observations of IPS since the early 1990s, and LOFAR successfully since 2011. The lower observing frequency of LOFAR allows us to probe further from the Sun in IPS that using EISCAT; however, two of the three mainland EISCAT telescopes are due to undergo a conversion to VHF frequencies (224 MHz) through late summer of 2012. This will result in a direct-observational overlap towards the high-frequency end of the observing capabilities using LOFAR (maximum observing frequency of 250 MHz) for IPS studies. Tests, where possible, will be explored with this new receiver system along with tests of the new EISCAT_3D test-bed, the Kilpisjärvi Atmospheric Imaging Receiver Array (KAIRA). This work comes one year following the death of Dr. Andy Breen who was one of the early pioneers of the IPS experiment on the early EISCAT system. Title: Multi-point Shock and Flux Rope Analysis of Multiple Interplanetary Coronal Mass Ejections around 2010 August 1 in the Inner Heliosphere Authors: Möstl, C.; Farrugia, C. J.; Kilpua, E. K. J.; Jian, L. K.; Liu, Y.; Eastwood, J. P.; Harrison, R. A.; Webb, D. F.; Temmer, M.; Odstrcil, D.; Davies, J. A.; Rollett, T.; Luhmann, J. G.; Nitta, N.; Mulligan, T.; Jensen, E. A.; Forsyth, R.; Lavraud, B.; de Koning, C. A.; Veronig, A. M.; Galvin, A. B.; Zhang, T. L.; Anderson, B. J. Bibcode: 2012ApJ...758...10M Altcode: 2012arXiv1209.2866M We present multi-point in situ observations of a complex sequence of coronal mass ejections (CMEs) which may serve as a benchmark event for numerical and empirical space weather prediction models. On 2010 August 1, instruments on various space missions, Solar Dynamics Observatory/Solar and Heliospheric Observatory/Solar-TErrestrial-RElations-Observatory (SDO/SOHO/STEREO), monitored several CMEs originating within tens of degrees from the solar disk center. We compare their imprints on four widely separated locations, spanning 120° in heliospheric longitude, with radial distances from the Sun ranging from MESSENGER (0.38 AU) to Venus Express (VEX, at 0.72 AU) to Wind, ACE, and ARTEMIS near Earth and STEREO-B close to 1 AU. Calculating shock and flux rope parameters at each location points to a non-spherical shape of the shock, and shows the global configuration of the interplanetary coronal mass ejections (ICMEs), which have interacted, but do not seem to have merged. VEX and STEREO-B observed similar magnetic flux ropes (MFRs), in contrast to structures at Wind. The geomagnetic storm was intense, reaching two minima in the Dst index (≈ - 100 nT), and was caused by the sheath region behind the shock and one of two observed MFRs. MESSENGER received a glancing blow of the ICMEs, and the events missed STEREO-A entirely. The observations demonstrate how sympathetic solar eruptions may immerse at least 1/3 of the heliosphere in the ecliptic with their distinct plasma and magnetic field signatures. We also emphasize the difficulties in linking the local views derived from single-spacecraft observations to a consistent global picture, pointing to possible alterations from the classical picture of ICMEs. Title: Multi-point shock and flux rope analysis of multiple ICMEs around 2010 August 1 in the inner heliosphere Authors: Moestl, Christian; Farrugia, C. J.; Kilpua, E. K. J.; Jian, L.; Liu, Y.; Jensen, L.; Mulligan, T.; Eastwood, J.; Rollett, T.; Temmer, M.; Luhmann, J. G.; Harrison, R.; Davies, J. A.; Webb, D.; Forsyth, R.; Lavraud, B.; Odstrcil, D.; de Koning, C. A.; Nitta, N.; Veronig, A. M.; Galvin, A. B.; Zhang, T. L. Bibcode: 2012shin.confE..77M Altcode: We present multi-point in situ observations of a complex sequence of coronal mass ejections which may serve as a benchmark event for numerical and empirical space weather prediction models. On 2010 August 1, instruments on various space missions (SDO/SOHO/STEREO) monitored repeated coronal mass ejections originating within tens of degrees from solar disk center. We compare their imprints on four widely separated locations, covering 120 degree in heliospheric longitude, with radial distances from the Sun ranging from MESSENGER (0.38 AU) to Venus Express (VEX, at 0.72 AU) to Wind, ACE and ARTEMIS near Earth and STEREO-B close to 1 AU. Calculating shock and flux rope parameters at each location points to a non-spherical shape of the shock, and shows the global configuration of the interplanetary coronal mass ejections (ICMEs), which have interacted but not merged, making individual identifications still possible. VEX and STEREO-B observed similar magnetic flux ropes, in contrast to the structures at Wind. The geomagnetic storm was moderate to major, reaching two minima in the Dst index, caused by the sheath region behind the shock and one of two observed magnetic flux ropes. MESSENGER received a glancing blow of the ICMEs, and the events missed STEREO-A entirely. The observations demonstrate how sympathetic solar eruptions may immerse at least 1/3 of the heliosphere in the ecliptic with their distinct plasma and magnetic field signatures and emphasize the difficulties in linking the local views derived from single-spacecraft observations to a consistent global picture, pointing to possible alterations from the classical picture of ICMEs. Title: An Analysis of the Origin and Propagation of the Multiple Coronal Mass Ejections of 2010 August 1 Authors: Harrison, R. A.; Davies, J. A.; Möstl, C.; Liu, Y.; Temmer, M.; Bisi, M. M.; Eastwood, J. P.; de Koning, C. A.; Nitta, N.; Rollett, T.; Farrugia, C. J.; Forsyth, R. J.; Jackson, B. V.; Jensen, E. A.; Kilpua, E. K. J.; Odstrcil, D.; Webb, D. F. Bibcode: 2012ApJ...750...45H Altcode: On 2010 August 1, the northern solar hemisphere underwent significant activity that involved a complex set of active regions near central meridian with, nearby, two large prominences and other more distant active regions. This activity culminated in the eruption of four major coronal mass ejections (CMEs), effects of which were detected at Earth and other solar system bodies. Recognizing the unprecedented wealth of data from the wide range of spacecraft that were available—providing the potential for us to explore methods for CME identification and tracking, and to assess issues regarding onset and planetary impact—we present a comprehensive analysis of this sequence of CMEs. We show that, for three of the four major CMEs, onset is associated with prominence eruption, while the remaining CME appears to be closely associated with a flare. Using instrumentation on board the Solar Terrestrial Relations Observatory spacecraft, three of the CMEs could be tracked out to elongations beyond 50° their directions and speeds have been determined by various methods, not least to assess their potential for Earth impact. The analysis techniques that can be applied to the other CME, the first to erupt, are more limited since that CME was obscured by the subsequent, much faster event before it had propagated far from the Sun; we discuss the speculation that these two CMEs interact. The consistency of the results, derived from the wide variety of methods applied to such an extraordinarily complete data set, has allowed us to converge on robust interpretations of the CME onsets and their arrivals at 1 AU. Title: A Self-similar Expansion Model for Use in Solar Wind Transient Propagation Studies Authors: Davies, J. A.; Harrison, R. A.; Perry, C. H.; Möstl, C.; Lugaz, N.; Rollett, T.; Davis, C. J.; Crothers, S. R.; Temmer, M.; Eyles, C. J.; Savani, N. P. Bibcode: 2012ApJ...750...23D Altcode: Since the advent of wide-angle imaging of the inner heliosphere, a plethora of techniques have been developed to investigate the three-dimensional structure and kinematics of solar wind transients, such as coronal mass ejections, from their signatures in single- and multi-spacecraft imaging observations. These techniques, which range from the highly complex and computationally intensive to methods based on simple curve fitting, all have their inherent advantages and limitations. In the analysis of single-spacecraft imaging observations, much use has been made of the fixed phi fitting (FPF) and harmonic mean fitting (HMF) techniques, in which the solar wind transient is considered to be a radially propagating point source (fixed phi, FP, model) and a radially expanding circle anchored at Sun centre (harmonic mean, HM, model), respectively. Initially, we compare the radial speeds and propagation directions derived from application of the FPF and HMF techniques to a large set of STEREO/Heliospheric Imager (HI) observations. As the geometries on which these two techniques are founded constitute extreme descriptions of solar wind transients in terms of their extent along the line of sight, we describe a single-spacecraft fitting technique based on a more generalized model for which the FP and HM geometries form the limiting cases. In addition to providing estimates of a transient's speed and propagation direction, the self-similar expansion fitting (SSEF) technique provides, in theory, the capability to estimate the transient's angular extent in the plane orthogonal to the field of view. Using the HI observations, and also by performing a Monte Carlo simulation, we assess the potential of the SSEF technique. Title: The first STEREO multi-event: Numerical simulation of coronal mass ejections (CMEs) launched on August 1, 2010 Authors: Odstrcil, D.; de Koning, C. A.; Xie, H.; Moestl, C.; Temmer, M.; Jian, L.; Rouillard, A. P.; Davies, J. A.; Davis, C. J.; Harrison, R. Bibcode: 2012EGUGA..1414429O Altcode: On 2010-08-01 at least four coronal mass ejections (CMEs) were observed by the Heliospheric Imagers (HIs) onboard STEREO spacecraft. These events originated at different parts of the solar corona and generated complex scenario of four mutually interacting CMEs. Real-time prediction of the arrival times to Earth failed and it is difficult to associate features observed by HIs with their solar sources and impacts at spacecraft. We use the heliospheric code ENLIL to show the global solution for various scenarios using fitted CME parameters from coronagraph observations by different techniques. We present the temporal profiles and synthetic white-light images that enables direct comparison with in-situ and remote observations. These results show that in addition to multi-perspective coronagraph observations, heliospheric imagers and numerical simulations are needed to understand and predict the impact of complex heliospheric disturbances. Title: CME-CME interaction during the 2010 August 1 events Authors: Temmer, M.; Vrsnak, B.; Rollett, T.; Bein, B.; deKoning, C. A.; Liu, Y.; Bosman, E.; Davies, J. A.; Möstl, C.; Zic, T.; Veronig, A. M.; Bothmer, V.; Harrison, R.; Nitta, N.; Bisi, M.; Flor, O.; Eastwood, J.; Odstrcil, D.; Forsyth, R. Bibcode: 2012EGUGA..14.1677T Altcode: We study a CME-CME interaction that occurred during the 2010 August 1 events using STEREO/SECCHI data (COR and HI). The CMEs were Earth directed where clear signatures of magnetic flux ropes could be measured from in situ Wind data. To give evidence of the actual interaction we derive the direction of motion for both CMEs applying several independent methods. From this we obtain that both CMEs head into similar directions enabling us to actually observe the merging in the HI1 field-of-view (and rule out the possibility that this is just a line of sight effect). The full de-projected kinematics of the faster CME from Sun to Earth is derived when combining data points from remote observations with in situ parameters of the ICME measured at 1 AU. We study the evolution of the kinematical profile of the faster CME by applying a drag based model. Title: Characteristics of Kinematics of a Coronal Mass Ejection during the 2010 August 1 CME-CME Interaction Event Authors: Temmer, Manuela; Vršnak, Bojan; Rollett, Tanja; Bein, Bianca; de Koning, Curt A.; Liu, Ying; Bosman, Eckhard; Davies, Jackie A.; Möstl, Christian; Žic, Tomislav; Veronig, Astrid M.; Bothmer, Volker; Harrison, Richard; Nitta, Nariaki; Bisi, Mario; Flor, Olga; Eastwood, Jonathan; Odstrcil, Dusan; Forsyth, Robert Bibcode: 2012ApJ...749...57T Altcode: 2012arXiv1202.0629T We study the interaction of two successive coronal mass ejections (CMEs) during the 2010 August 1 events using STEREO/SECCHI COR and heliospheric imager (HI) data. We obtain the direction of motion for both CMEs by applying several independent reconstruction methods and find that the CMEs head in similar directions. This provides evidence that a full interaction takes place between the two CMEs that can be observed in the HI1 field of view. The full de-projected kinematics of the faster CME from Sun to Earth is derived by combining remote observations with in situ measurements of the CME at 1 AU. The speed profile of the faster CME (CME2; ~1200 km s-1) shows a strong deceleration over the distance range at which it reaches the slower, preceding CME (CME1; ~700 km s-1). By applying a drag-based model we are able to reproduce the kinematical profile of CME2, suggesting that CME1 represents a magnetohydrodynamic obstacle for CME2 and that, after the interaction, the merged entity propagates as a single structure in an ambient flow of speed and density typical for quiet solar wind conditions. Observational facts show that magnetic forces may contribute to the enhanced deceleration of CME2. We speculate that the increase in magnetic tension and pressure, when CME2 bends and compresses the magnetic field lines of CME1, increases the efficiency of drag. Title: Interactions between Coronal Mass Ejections Viewed in Coordinated Imaging and in situ Observations Authors: Liu, Ying D.; Luhmann, Janet G.; Möstl, Christian; Martinez-Oliveros, Juan C.; Bale, Stuart D.; Lin, Robert P.; Harrison, Richard A.; Temmer, Manuela; Webb, David F.; Odstrcil, Dusan Bibcode: 2012ApJ...746L..15L Altcode: 2012arXiv1201.2968L The successive coronal mass ejections (CMEs) from 2010 July 30 to August 1 present us the first opportunity to study CME-CME interactions with unprecedented heliospheric imaging and in situ observations from multiple vantage points. We describe two cases of CME interactions: merging of two CMEs launched close in time and overtaking of a preceding CME by a shock wave. The first two CMEs on August 1 interact close to the Sun and form a merged front, which then overtakes the July 30 CME near 1 AU, as revealed by wide-angle imaging observations. Connections between imaging observations and in situ signatures at 1 AU suggest that the merged front is a shock wave, followed by two ejecta observed at Wind which seem to have already merged. In situ measurements show that the CME from July 30 is being overtaken by the shock at 1 AU and is significantly compressed, accelerated, and heated. The interaction between the preceding ejecta and shock also results in variations in the shock strength and structure on a global scale, as shown by widely separated in situ measurements from Wind and STEREO B. These results indicate important implications of CME-CME interactions for shock propagation, particle acceleration, and space weather forecasting. Title: Transient Structure in the Slow Solar Wind Authors: Hardwick, S. A.; Breen, A.; Bisi, M. M.; Fallows, R. A.; Davies, J. A.; Harrison, R.; Davis, C. J. Bibcode: 2011AGUFMSH22A..07H Altcode: Solar TErrestrial RElations Observatory (STEREO) Heliospheric Imager (HI) observations of the slow solar wind commonly show a high degree of small-scale structure. High-cadence analyses of two-station radio scintillation observations (IPS) from the EISCAT facility also show evidence of rapid variation in outflow speed, scintillation level, and magnetic-field orientation in the slow wind. These are on spatial scales smaller than the structures seen by the HIs. We compare observations of IPS of solar-wind outflow speed and field orientation made at times of good HI coverage with HI white-light intensity levels in order to determine whether the IPS variations are embedded within larger transients observed by the HIs. Title: Interaction between Coronal Mass Ejections Viewed in Coordinated Imaging and In Situ Observations Authors: Liu, Y.; Luhmann, J. G.; Moestl, C.; Martinez Oliveros, J. C.; Harrison, R.; Temmer, M.; Bale, S.; Lin, R. P. Bibcode: 2011AGUFMSH23C1973L Altcode: Interaction between coronal mass ejections (CMEs), which is expected to be a frequent phenomenon, has important implications for both space weather and basic plasma physics. First, the interaction alters the global heliospheric configuration, which may lead to favorable conditions for geomagnetic storm generation. Second, the interaction implies significant energy and momentum transfer between the interacting CMEs where magnetic reconnection may take place. Third, in case a shock is driven by the trailing CME, interesting physical processes may occur when the shock is propagating through the preceding one, such as modifications in the shock strength, particle intensity and transport. There are successive CMEs on July 30 - August 1, 2011, which presents us the first opportunity to study CME-CME interaction with unprecedented heliospheric imaging and in situ observations from a fleet of spacecraft. The first two CMEs on August 1 interact close to the Sun and form a merged front, which then overtakes the July 30 CME near 1 AU, as revealed by wide-angle imaging observations. In situ measurements indicate that the first two CMEs on August 1 seem to have already merged at 0.7 and 1 AU, and at 1 AU their shock is propagating into the CME from July 30. We will report and discuss the CME-CME interaction signatures from the coordinated imaging and in situ observations in this presentation. Title: The first STEREO multi-event: Numerical simulation of coronal mass ejections (CMEs) launched on August 1, 2010 Authors: Odstrcil, D.; de Koning, C. A.; Xie, H.; Moestl, C.; Temmer, M.; Jian, L.; Rouillard, A. P.; Davies, J. A.; Davis, C. J.; Harrison, R. Bibcode: 2011AGUFMSH32A..03O Altcode: On 2010-08-01 at least four coronal mass ejections (CMEs) were observed by the Heliospheric Imagers (HIs) onboard STEREO spacecraft. These events originated at different parts of the solar corona and generated complex scenario of four mutually interacting CMEs. Real-time prediction of the arrival times to Earth failed and it is difficult to associate features observed by HIs with their solar sources and impacts at spacecraft. We use the heliospheric code ENLIL to show the global solution for two scenarios using fitted CME parameters from coronagraph observations by two different techniques. We present the temporal profiles and synthetic white-light images that enables direct comparison with in-situ and remote observations. These results show that in addition to multi-perspective coronagraph observations, heliospheric imagers and numerical simulations are needed to understand and predict the impact of complex heliospheric disturbances. Title: Arrival Time Calculation for Interplanetary Coronal Mass Ejections with Circular Fronts and Application to STEREO Observations of the 2009 February 13 Eruption Authors: Möstl, C.; Rollett, T.; Lugaz, N.; Farrugia, C. J.; Davies, J. A.; Temmer, M.; Veronig, A. M.; Harrison, R. A.; Crothers, S.; Luhmann, J. G.; Galvin, A. B.; Zhang, T. L.; Baumjohann, W.; Biernat, H. K. Bibcode: 2011ApJ...741...34M Altcode: 2011arXiv1108.0515M One of the goals of the NASA Solar TErestrial RElations Observatory (STEREO) mission is to study the feasibility of forecasting the direction, arrival time, and internal structure of solar coronal mass ejections (CMEs) from a vantage point outside the Sun-Earth line. Through a case study, we discuss the arrival time calculation of interplanetary CMEs (ICMEs) in the ecliptic plane using data from STEREO/SECCHI at large elongations from the Sun in combination with different geometric assumptions about the ICME front shape [fixed-Φ (FP): a point and harmonic mean (HM): a circle]. These forecasting techniques use single-spacecraft imaging data and are based on the assumption of constant velocity and direction. We show that for the slow (350 km s-1) ICME on 2009 February 13-18, observed at quadrature by the two STEREO spacecraft, the results for the arrival time given by the HM approximation are more accurate by 12 hr than those for FP in comparison to in situ observations of solar wind plasma and magnetic field parameters by STEREO/IMPACT/PLASTIC, and by 6 hr for the arrival time at Venus Express (MAG). We propose that the improvement is directly related to the ICME front shape being more accurately described by HM for an ICME with a low inclination of its symmetry axis to the ecliptic. In this case, the ICME has to be tracked to >30° elongation to obtain arrival time errors < ± 5 hr. A newly derived formula for calculating arrival times with the HM method is also useful for a triangulation technique assuming the same geometry. Title: Propagation and impact of multiple coronal mass ejections events on August 1 2010 in the heliosphere Authors: Möstl, Christian; Farrugia, Charles J.; Harrison, Richard A.; Davies, J. A.; Kilpua, Emilia K. J.; Odstrcil, Dusan; Rollett, Tanja; Temmer, Manuela; Veronig, Astrid; Jian, Lan; Liu, Ying; Eastwood, Jonathan; Forsyth, Robert; Webb, David; Bisi, Mario M.; Jackson, Bernard V.; Mulligan, Tamitha; Jensen, Liz; Lavraud, Benoit; de Koning, Curt A.; Nitta, Nariaki; Luhmann, Janet; Galvin, Antoinette B.; Zhang, Tielong Bibcode: 2011sdmi.confE..69M Altcode: On August 1 2010 a large region of the solar northern hemisphere displayed major activity involving a complex set of central meridian and remote active regions, and two large prominence channels (Schrijver and Title, JGR, 2011). We witnessed the eruption of four coronal mass ejections (CMEs) which partly impacted Earth and lead to one of the first geomagnetic storms of the new solar cycle. We present an overview of the results of several analyses exploiting the extraordinary completeness of the imaging data (SDO/STEREO/SOHO) in combination with numerical simulations (ENLIL) and in situ observations. The imprints of the CMEs, including a prior event on July 30, were observed in situ in an almost laboratory-like configuration at 4 widely separated locations spanning over 120 degrees of heliospheric longitude (STEREO-B, Venus Express, ACE/Wind, ARTEMIS, and MESSENGER). The CME density enhancements could be followed with the STEREO-A/HI and Coriolis/SMEI instruments continuously from the Sun to 1 AU. Evidences of CME-CME interactions and resulting overlapping tracks in Jmaps make the analysis complex, but nevertheless we find robust interpretations for linking two magnetic flux ropes at Earth, one of them geo-effective and including elevated alpha particles related to possible filament material, to their solar counterparts. Additionally, we discuss the relationship between the in situ observations and the global picture given by the ENLIL model. Title: Straylight-Rejection Performance of the STEREO HI Instruments Authors: Halain, J. -P.; Eyles, C. J.; Mazzoli, A.; Bewsher, D.; Davies, J. A.; Mazy, E.; Rochus, P.; Defise, J. M.; Davis, C. J.; Harrison, R. A.; Crothers, S. R.; Brown, D. S.; Korendyke, C.; Moses, J. D.; Socker, D. G.; Howard, R. A.; Newmark, J. S. Bibcode: 2011SoPh..271..197H Altcode: 2011SoPh..tmp..189H; 2011SoPh..tmp..132H; 2011SoPh..tmp..258H The SECCHI Heliospheric Imager (HI) instruments on-board the STEREO spacecraft have been collecting images of solar wind transients, including coronal mass ejections, as they propagate through the inner heliosphere since the beginning of 2007. Title: A unique view of the inner heliosphere from the STEREO Heliospheric Imagers (Invited) Authors: Davis, C. J.; Harrison, R. A.; Davies, J. A.; Crothers, S. R.; Eyles, C. J. Bibcode: 2010AGUFMSH52B..01D Altcode: Launched in 2006, the twin spacecraft of the STEREO mission have provided unique views of the Sun and the inner heliosphere in three dimensions. One pair of instruments in particular, the Heliospheric Imagers, have revolutionised the way that solar transients, in particular Earth-directed coronal mass ejections, can be viewed. This talk will summarise the observations so far, review the techniques developed to interpret the data and discuss how these techniques will help to inform future space-weather missions. A CME (right) passes in front of the Milky Way (left) and Jupiter (left center) observed with STEREO HI, November 2007. Title: Science Objectives for an X-Ray Microcalorimeter Observing the Sun Authors: Laming, J. Martin; Adams, J.; Alexander, D.; Aschwanden, M; Bailey, C.; Bandler, S.; Bookbinder, J.; Bradshaw, S.; Brickhouse, N.; Chervenak, J.; Christe, S.; Cirtain, J.; Cranmer, S.; Deiker, S.; DeLuca, E.; Del Zanna, G.; Dennis, B.; Doschek, G.; Eckart, M.; Fludra, A.; Finkbeiner, F.; Grigis, P.; Harrison, R.; Ji, L.; Kankelborg, C.; Kashyap, V.; Kelly, D.; Kelley, R.; Kilbourne, C.; Klimchuk, J.; Ko, Y. -K.; Landi, E.; Linton, M.; Longcope, D.; Lukin, V.; Mariska, J.; Martinez-Galarce, D.; Mason, H.; McKenzie, D.; Osten, R.; Peres, G.; Pevtsov, A.; Porter, K. Phillips F. S.; Rabin, D.; Rakowski, C.; Raymond, J.; Reale, F.; Reeves, K.; Sadleir, J.; Savin, D.; Schmelz, J.; Smith, R. K.; Smith, S.; Stern, R.; Sylwester, J.; Tripathi, D.; Ugarte-Urra, I.; Young, P.; Warren, H.; Wood, B. Bibcode: 2010arXiv1011.4052L Altcode: We present the science case for a broadband X-ray imager with high-resolution spectroscopy, including simulations of X-ray spectral diagnostics of both active regions and solar flares. This is part of a trilogy of white papers discussing science, instrument (Bandler et al. 2010), and missions (Bookbinder et al. 2010) to exploit major advances recently made in transition-edge sensor (TES) detector technology that enable resolution better than 2 eV in an array that can handle high count rates. Combined with a modest X-ray mirror, this instrument would combine arcsecondscale imaging with high-resolution spectra over a field of view sufficiently large for the study of active regions and flares, enabling a wide range of studies such as the detection of microheating in active regions, ion-resolved velocity flows, and the presence of non-thermal electrons in hot plasmas. It would also enable more direct comparisons between solar and stellar soft X-ray spectra, a waveband in which (unusually) we currently have much better stellar data than we do of the Sun. Title: Transient Structures and Stream Interaction Regions in the Solar Wind: Results from EISCAT Interplanetary Scintillation, STEREO HI and Venus Express ASPERA-4 Measurements Authors: Dorrian, G. D.; Breen, A. R.; Davies, J. A.; Rouillard, A. P.; Fallows, R. A.; Whittaker, I. C.; Brown, D. S.; Harrison, R. A.; Davis, C. J.; Grande, M. Bibcode: 2010SoPh..265..207D Altcode: 2010SoPh..tmp..134D; 2012arXiv1207.3968D We discuss the detection and evolution of a complex series of transient and quasi-static solar-wind structures in the days following the well-known comet 2P/Encke tail disconnection event in April 2007. The evolution of transient solar-wind structures ranging in size from <105 km to >106 km was characterised using one-minute time resolution observation of Interplanetary Scintillation (IPS) made using the European Incoherent SCATter (EISCAT) radar system. Simultaneously, the global structure and evolution of these features was characterised by the Heliospheric Imagers (HI) on the Solar TERrestrial RElations Observatory (STEREO) spacecraft, placing the IPS observations in context. Of particular interest was the observation of one transient in the slow wind, apparently being swept up and entrained by a Stream Interaction Region (SIR). The SIR itself was later detected in-situ at Venus by the Analyser of Space Plasma and Energetic Atoms (ASPERA-4) instrument on the Venus Express (VEX) spacecraft. The availability of such diverse data sources over a range of different time resolutions enables us to develop a global picture of these complex events that would not have been possible if these instruments were used in isolation. We suggest that the range of solar-wind transients discussed here may be the interplanetary counterparts of transient structures previously reported from coronagraph observations and are likely to correspond to transient magnetic structures reported in in-situ measurements in interplanetary space. The results reported here also provide the first indication of heliocentric distances at which transients become entrained. Title: Intermittent release of transients in the slow solar wind: 2. In situ evidence Authors: Rouillard, A. P.; Lavraud, B.; Davies, J. A.; Savani, N. P.; Burlaga, L. F.; Forsyth, R. J.; Sauvaud, J. -A.; Opitz, A.; Lockwood, M.; Luhmann, J. G.; Simunac, K. D. C.; Galvin, A. B.; Davis, C. J.; Harrison, R. A. Bibcode: 2010JGRA..115.4104R Altcode: 2010JGRA..11504104R In paper 1, we showed that the Heliospheric Imager (HI) instruments on the pair of NASA STEREO spacecraft can be used to image the streamer belt and, in particular, the variability of the slow solar wind which originates near helmet streamers. The observation of intense intermittent transient outflow by HI implies that the corresponding in situ observations of the slow solar wind and corotating interaction regions (CIRs) should contain many signatures of transients. In the present paper, we compare the HI observations with in situ measurements from the STEREO and ACE spacecraft. Analysis of the solar wind ion, magnetic field, and suprathermal electron flux measurements from the STEREO spacecraft reveals the presence of both closed and partially disconnected interplanetary magnetic field lines permeating the slow solar wind. We predict that one of the transients embedded within the second CIR (CIR-D in paper 1) should impact the near-Earth ACE spacecraft. ACE measurements confirm the presence of a transient at the time of CIR passage; the transient signature includes helical magnetic fields and bidirectional suprathermal electrons. On the same day, a strahl electron dropout is observed at STEREO-B, correlated with the passage of a high-plasma beta structure. Unlike ACE, STEREO-B observes the transient a few hours ahead of the CIR. STEREO-A, STEREO-B, and ACE spacecraft observe very different slow solar wind properties ahead of and during the CIR analyzed in this paper, which we associate with the intermittent release of transients. Title: Intermittent release of transients in the slow solar wind: 1. Remote sensing observations Authors: Rouillard, A. P.; Davies, J. A.; Lavraud, B.; Forsyth, R. J.; Savani, N. P.; Bewsher, D.; Brown, D. S.; Sheeley, N. R.; Davis, C. J.; Harrison, R. A.; Howard, R. A.; Vourlidas, A.; Lockwood, M.; Crothers, S. R.; Eyles, C. J. Bibcode: 2010JGRA..115.4103R Altcode: 2010JGRA..11504103R The Heliospheric Imager (HI) instruments on board the STEREO spacecraft are used to analyze the solar wind during August and September 2007. We show how HI can be used to image the streamer belt and, in particular, the variability of the slow solar wind which originates inside and in the vicinity of the streamer belt. Intermittent mass flows are observed in HI difference images, streaming out along the extension of helmet streamers. These flows can appear very differently in images: plasma distributed on twisted flux ropes, V-shaped structures, or “blobs.” The variety of these transient features may highlight the richness of phenomena that could occur near helmet streamers: emergence of flux ropes, reconnection of magnetic field lines at the tip of helmet streamers, or disconnection of open magnetic field lines. The plasma released with these transient events forms part of the solar wind in the higher corona; HI observations show that these transients are frequently entrained by corotating interaction regions (CIRs), leading to the formation of larger, brighter plasma structures in HI images. This entrainment is used to estimate the trajectory of these plasma ejecta. In doing so, we demonstrate that successive transients can be entrained by the same CIR in the high corona if they emanate from the same corotating source. Some parts of the streamers are more effective sources of transients than others. Surprisingly, evidence is given for the outflow of a recurring twisted magnetic structure, suggesting that the emergence of flux ropes can be recurrent. Title: Coronal mass ejections in the heliosphere Authors: Harrison, R. A.; Davis, C. J.; Bewsher, D.; Davies, J. A.; Eyles, C. J.; Crothers, S. R. Bibcode: 2010AdSpR..45....1H Altcode: With the advent of the NASA STEREO mission, we are in a position to perform unique investigations of the evolution of coronal mass ejections (CMEs) as they propagate through the heliosphere, and thus can investigate the relationship between CMEs and their interplanetary counterparts, so-called interplanetary CMEs (ICMEs). ICME studies have been principally limited to single-point, in-situ observations; interpretation of the in-situ characteristics of ICMEs has been used to derive a range of ICME properties which we can now confirm or refute using the STEREO imaging data. This paper is a review of early STEREO CME observations and how they relate to our currently understanding of ICMEs based on in-situ observations. In that sense, it is a first glance at the applications of the new data-sets to this topic and provides pointers to more detailed analyses. We find good agreement with in-situ-based interpretations, but this in turn leads to an anomaly regarding the final stages of a CME event that we investigate briefly to identify directions for future study. Title: The radial width of a Coronal Mass Ejection between 0.1 and 0.4 AU estimated from the Heliospheric Imager on STEREO Authors: Savani, N. P.; Rouillard, A. P.; Davies, J. A.; Owens, M. J.; Forsyth, R. J.; Davis, C. J.; Harrison, R. A. Bibcode: 2009AnGeo..27.4349S Altcode: On 15-17 February 2008, a CME with an approximately circular cross section was tracked through successive images obtained by the Heliospheric Imager (HI) instrument onboard the STEREO-A spacecraft. Reasoning that an idealised flux rope is cylindrical in shape with a circular cross-section, best fit circles are used to determine the radial width of the CME. As part of the process the radial velocity and longitude of propagation are determined by fits to elongation-time maps as 252±5 km/s and 70±5° respectively. With the longitude known, the radial size is calculated from the images, taking projection effects into account. The radial width of the CME, S (AU), obeys a power law with heliocentric distance, R, as the CME travels between 0.1 and 0.4 AU, such that S=0.26 R0.6±0.1. The exponent value obtained is compared to published studies based on statistical surveys of in situ spacecraft observations of ICMEs between 0.3 and 1.0 AU, and general agreement is found. This paper demonstrates the new opportunities provided by HI to track the radial width of CMEs through the previously unobservable zone between the LASCO field of view and Helios in situ measurements. Title: Pre-CME Onset Fuses - Do the STEREO Heliospheric Imagers Hold the Clues to the CME Onset Process? Authors: Harrison, Richard A.; Davis, Christopher J.; Davies, Jackie A. Bibcode: 2009SoPh..259..277H Altcode: Understanding the onset of coronal mass ejections (CMEs) is surely one of the holy grails of solar physics today. Inspection of data from the Heliospheric Imagers (HI), which are part of the SECCHI instrument suite aboard the two NASA STEREO spacecraft, appears to have revealed pre-eruption signatures which may provide valuable evidence for identifying the CME onset mechanism. Specifically, an examination of the HI images has revealed narrow rays comprised of a series of outward-propagating plasma blobs apparently forming near the edge of the streamer belt prior to many CME eruptions. In this pilot study, we inspect a limited dataset to explore the significance of this phenomenon, which we have termed a pre-CME `fuse'. Although, the enhanced expulsion of blobs may be consistent with an increase in the release of outward-propagating blobs from the streamers themselves, it could also be interpreted as evidence for interchange reconnection in the period leading to a CME onset. Indeed, it is argued that the latter could even have implications for the end-of-life of CMEs. Thus, the presence of these pre-CME fuses provides evidence that the CME onset mechanism is either related to streamer reconnection processes or the reconnection between closed field lines in the streamer belt and adjacent, open field lines. We investigate the nature of these fuses, including their timing and location with respect to CME launch sites, as well as their speed and topology. Title: Virtual Observatory studies of Planetary Nebulae Authors: Mignani, R. P.; Kerber, F.; Smart, R. L.; Vande Putte, D.; Wicenec, A.; Rauch, T.; Adorf, H. M.; Harrison, R. Bibcode: 2009mavo.proc..173M Altcode: 2009arXiv0902.0960M Starting from the Strasbourg ESO Catalogue (SEC) of Planetary Nebulae (PNe), the largest PNe compilation available with ~ 1500 objects, we undertook a comprehensive study of the whole PN population, never carried out so far, only using on-line catalogues and data from public imaging surveys. The study includes the PN dynamics through their measured proper motions (PMs), the study of their galactocentric orbits, the study of their interactions with the interstellar medium (ISM), and the study of their UV-to-IR spectral energy distribution (SED). As a preliminary step required to perform cross-correlations with on-line catalogues, we first went through a systematic reassessment of the PN coordinates (Kerber et al. 2003a). Title: A solar storm observed from the Sun to Venus using the STEREO, Venus Express, and MESSENGER spacecraft Authors: Rouillard, A. P.; Davies, J. A.; Forsyth, R. J.; Savani, N. P.; Sheeley, N. R.; Thernisien, A.; Zhang, T. -L.; Howard, R. A.; Anderson, B.; Carr, C. M.; Tsang, S.; Lockwood, M.; Davis, C. J.; Harrison, R. A.; Bewsher, D.; Fränz, M.; Crothers, S. R.; Eyles, C. J.; Brown, D. S.; Whittaker, I.; Hapgood, M.; Coates, A. J.; Jones, G. H.; Grande, M.; Frahm, R. A.; Winningham, J. D. Bibcode: 2009JGRA..114.7106R Altcode: 2009JGRA..11407106R The suite of SECCHI optical imaging instruments on the STEREO-A spacecraft is used to track a solar storm, consisting of several coronal mass ejections (CMEs) and other coronal loops, as it propagates from the Sun into the heliosphere during May 2007. The 3-D propagation path of the largest interplanetary CME (ICME) is determined from the observations made by the SECCHI Heliospheric Imager (HI) on STEREO-A (HI-1/2A). Two parts of the CME are tracked through the SECCHI images, a bright loop and a V-shaped feature located at the rear of the event. We show that these two structures could be the result of line-of-sight integration of the light scattered by electrons located on a single flux rope. In addition to being imaged by HI, the CME is observed simultaneously by the plasma and magnetic field experiments on the Venus Express and MESSENGER spacecraft. The imaged loop and V-shaped structure bound, as expected, the flux rope observed in situ. The SECCHI images reveal that the leading loop-like structure propagated faster than the V-shaped structure, and a decrease in in situ CME speed occurred during the passage of the flux rope. We interpret this as the result of the continuous radial expansion of the flux rope as it progressed outward through the interplanetary medium. An expansion speed in the radial direction of ∼30 km s-1 is obtained directly from the SECCHI-HI images and is in agreement with the difference in speed of the two structures observed in situ. This paper shows that the flux rope location can be determined from white light images, which could have important space weather applications. Title: A Multispacecraft Analysis of a Small-Scale Transient Entrained by Solar Wind Streams Authors: Rouillard, A. P.; Savani, N. P.; Davies, J. A.; Lavraud, B.; Forsyth, R. J.; Morley, S. K.; Opitz, A.; Sheeley, N. R.; Burlaga, L. F.; Sauvaud, J. -A.; Simunac, K. D. C.; Luhmann, J. G.; Galvin, A. B.; Crothers, S. R.; Davis, C. J.; Harrison, R. A.; Lockwood, M.; Eyles, C. J.; Bewsher, D.; Brown, D. S. Bibcode: 2009SoPh..256..307R Altcode: The images taken by the Heliospheric Imagers (HIs), part of the SECCHI imaging package onboard the pair of STEREO spacecraft, provide information on the radial and latitudinal evolution of the plasma compressed inside corotating interaction regions (CIRs). A plasma density wave imaged by the HI instrument onboard STEREO-B was found to propagate towards STEREO-A, enabling a comparison between simultaneous remote-sensing and in situ observations of its structure to be performed. In situ measurements made by STEREO-A show that the plasma density wave is associated with the passage of a CIR. The magnetic field compressed after the CIR stream interface (SI) is found to have a planar distribution. Minimum variance analysis of the magnetic field vectors shows that the SI is inclined at 54° to the orbital plane of the STEREO-A spacecraft. This inclination of the CIR SI is comparable to the inclination of the associated plasma density wave observed by HI. A small-scale magnetic cloud with a flux rope topology and radial extent of 0.08 AU is also embedded prior to the SI. The pitch-angle distribution of suprathermal electrons measured by the STEREO-A SWEA instrument shows that an open magnetic field topology in the cloud replaced the heliospheric current sheet locally. These observations confirm that HI observes CIRs in difference images when a small-scale transient is caught up in the compression region. Title: Study of CME Propagation in the Inner Heliosphere: SOHO LASCO, SMEI and STEREO HI Observations of the January 2007 Events Authors: Webb, D. F.; Howard, T. A.; Fry, C. D.; Kuchar, T. A.; Odstrcil, D.; Jackson, B. V.; Bisi, M. M.; Harrison, R. A.; Morrill, J. S.; Howard, R. A.; Johnston, J. C. Bibcode: 2009SoPh..256..239W Altcode: We are investigating the geometric and kinematic characteristics of interplanetary coronal mass ejections (ICMEs) using data obtained by the LASCO coronagraphs, the Solar Mass Ejection Imager (SMEI), and the SECCHI imaging experiments on the STEREO spacecraft. The early evolution of CMEs can be tracked by the LASCO C2 and C3 and SECCHI COR1 and COR2 coronagraphs, and the HI and SMEI instruments can track their ICME counterparts through the inner heliosphere. The HI fields of view (4 - 90°) overlap with the SMEI field of view (> 20° to all sky) and, thus, both instrument sets can observe the same ICME. In this paper we present results for ICMEs observed on 24 - 29 January 2007, when the STEREO spacecraft were still near Earth so that both the SMEI and STEREO views of large ICMEs in the inner heliosphere coincided. These results include measurements of the structural and kinematic evolution of two ICMEs and comparisons with drive/drag kinematic, 3D tomographic reconstruction, the HAFv2 kinematic, and the ENLIL MHD models. We find it encouraging that the four model runs generally were in agreement on both the kinematic evolution and appearance of the events. Because it is essential to understand the effects of projection across large distances, that are not generally crucial for events observed closer to the Sun, we discuss our analysis procedure in some detail. Title: Two Years of the STEREO Heliospheric Imagers. Invited Review Authors: Harrison, Richard A.; Davies, Jackie A.; Rouillard, Alexis P.; Davis, Christopher J.; Eyles, Christopher J.; Bewsher, Danielle; Crothers, Steve R.; Howard, Russell A.; Sheeley, Neil R.; Vourlidas, Angelos; Webb, David F.; Brown, Daniel S.; Dorrian, Gareth D. Bibcode: 2009SoPh..256..219H Altcode: Imaging of the heliosphere is a burgeoning area of research. As a result, it is awash with new results, using novel applications, and is demonstrating great potential for future research in a wide range of topical areas. The STEREO (Solar TErrestrial RElations Observatory) Heliospheric Imager (HI) instruments are at the heart of this new development, building on the pioneering observations of the SMEI (Solar Mass Ejection Imager) instrument aboard the Coriolis spacecraft. Other earlier heliospheric imaging systems have included ground-based interplanetary scintillation (IPS) facilities and the photometers on the Helios spacecraft. With the HI instruments, we now have routine wide-angle imaging of the inner heliosphere, from vantage points outside the Sun-Earth line. HI has been used to investigate the development of coronal mass ejections (CMEs) as they pass through the heliosphere to 1 AU and beyond. Synoptic mapping has also allowed us to see graphic illustrations of the nature of mass outflow as a function of distance from the Sun - in particular, stressing the complexity of the near-Sun solar wind. The instruments have also been used to image co-rotating interaction regions (CIRs), to study the interaction of comets with the solar wind and CMEs, and to witness the impact of CMEs and CIRs on planets. The very nature of this area of research - which brings together aspects of solar physics, space-environment physics, and solar-terrestrial physics - means that the research papers are spread among a wide range of journals from different disciplines. Thus, in this special issue, it is timely and appropriate to provide a review of the results of the first two years of the HI investigations. Title: STEREO SECCHI and S/WAVES Observations of Spacecraft Debris Caused by Micron-Size Interplanetary Dust Impacts Authors: St. Cyr, O. C.; Kaiser, M. L.; Meyer-Vernet, N.; Howard, R. A.; Harrison, R. A.; Bale, S. D.; Thompson, W. T.; Goetz, K.; Maksimovic, M.; Bougeret, J. -L.; Wang, D.; Crothers, S. Bibcode: 2009SoPh..256..475S Altcode: Early in the STEREO mission observers noted that the white-light instruments of the SECCHI suite were detecting significantly more spacecraft-related "debris" than any previously flown coronagraphic instruments. Comparison of SECCHI "debris storms" with S/WAVES indicates that almost all are coincident with the most intense transient emissions observed by the radio and plasma waves instrument. We believe the debris is endogenous (i.e., from the spacecraft thermal blanketing), and the storms appear to be caused by impacts of large interplanetary dust grains that are detected by S/WAVES. Here we report the observations, compare them to interplanetary dust distributions, and document a reminder for future spacebased coronagraphic instrument builders. Title: Stereoscopic imaging of an Earth-impacting solar coronal mass ejection: A major milestone for the STEREO mission Authors: Davis, C. J.; Davies, J. A.; Lockwood, M.; Rouillard, A. P.; Eyles, C. J.; Harrison, R. A. Bibcode: 2009GeoRL..36.8102D Altcode: 2009GeoRL..3608102D We present stereoscopic images of an Earth-impacting Coronal Mass Ejection (CME). The CME was imaged by the Heliospheric Imagers onboard the twin STEREO spacecraft during December 2008. The apparent acceleration of the CME is used to provide independent estimates of its speed and direction from the two spacecraft. Three distinct signatures within the CME were all found to be closely Earth-directed. At the time that the CME was predicted to pass the ACE spacecraft, in-situ observations contained a typical CME signature. At Earth, ground-based magnetometer observations showed a small but widespread sudden response to the compression of the geomagnetic cavity at CME impact. In this case, STEREO could have given warning of CME impact at least 24 hours in advance. These stereoscopic observations represent a significant milestone for the STEREO mission and have significant potential for improving operational space weather forecasting. Title: Coronal mass ejection: key issues Authors: Harrison, Richard Bibcode: 2009IAUS..257..191H Altcode: Coronal Mass Ejections (CMEs) have been addressed by a particularly active research community in recent years. With the advent of the International Heliophysical Year and the new STEREO and Hinode missions, in addition to the on-going SOHO mission, CME research has taken centre stage in a renewed international effort. This review aims to touch on some key observational areas, and their interpretation. First, we consider coronal dimming, which has become synonymous with CME onsets, and stress that recent advances have heralded a move from a perceived association between the two phenomena to a firm, well-defined physical link. What this means for our understanding of CME modeling is discussed. Second, with the new STEREO observations, and noting the on-going SMEI observations, it is important to review the opening field of CME studies in the heliosphere. Finally, we discuss some specific points with regard to EIT-waves and the flare-CME relationship. In the opinion of the author, these issues cover key hot topics which need consideration for significant progress in the field. Title: The Heliospheric Imagers Onboard the STEREO Mission Authors: Eyles, C. J.; Harrison, R. A.; Davis, C. J.; Waltham, N. R.; Shaughnessy, B. M.; Mapson-Menard, H. C. A.; Bewsher, D.; Crothers, S. R.; Davies, J. A.; Simnett, G. M.; Howard, R. A.; Moses, J. D.; Newmark, J. S.; Socker, D. G.; Halain, J. -P.; Defise, J. -M.; Mazy, E.; Rochus, P. Bibcode: 2009SoPh..254..387E Altcode: 2008SoPh..tmp..193E Mounted on the sides of two widely separated spacecraft, the two Heliospheric Imager (HI) instruments onboard NASA's STEREO mission view, for the first time, the space between the Sun and Earth. These instruments are wide-angle visible-light imagers that incorporate sufficient baffling to eliminate scattered light to the extent that the passage of solar coronal mass ejections (CMEs) through the heliosphere can be detected. Each HI instrument comprises two cameras, HI-1 and HI-2, which have 20° and 70° fields of view and are off-pointed from the Sun direction by 14.0° and 53.7°, respectively, with their optical axes aligned in the ecliptic plane. This arrangement provides coverage over solar elongation angles from 4.0° to 88.7° at the viewpoints of the two spacecraft, thereby allowing the observation of Earth-directed CMEs along the Sun - Earth line to the vicinity of the Earth and beyond. Given the two separated platforms, this also presents the first opportunity to view the structure and evolution of CMEs in three dimensions. The STEREO spacecraft were launched from Cape Canaveral Air Force Base in late October 2006, and the HI instruments have been performing scientific observations since early 2007. The design, development, manufacture, and calibration of these unique instruments are reviewed in this paper. Mission operations, including the initial commissioning phase and the science operations phase, are described. Data processing and analysis procedures are briefly discussed, and ground-test results and in-orbit observations are used to demonstrate that the performance of the instruments meets the original scientific requirements. Title: Commission 10: Solar Activity Authors: Klimchuk, James A.; van Driel-Gesztelyi, Lidia; Schrijver, Carolus J.; Melrose, Donald B.; Fletcher, Lyndsay; Gopalswamy, Natchimuthuk; Harrison, Richard A.; Mandrini, Cristina H.; Peter, Hardi; Tsuneta, Saku; Vršnak, Bojan; Wang, Jing-Xiu Bibcode: 2009IAUTA..27...79K Altcode: 2008arXiv0809.1444K Commission 10 deals with solar activity in all of its forms, ranging from the smallest nanoflares to the largest coronal mass ejections. This report reviews scientific progress over the roughly two-year period ending in the middle of 2008. This has been an exciting time in solar physics, highlighted by the launches of the Hinode and STEREO missions late in 2006. The report is reasonably comprehensive, though it is far from exhaustive. Limited space prevents the inclusion of many significant results. The report is divided into the following sections: Photosphere and chromosphere; Transition region; Corona and coronal heating; Coronal jets; flares; Coronal mass ejection initiation; Global coronal waves and shocks; Coronal dimming; The link between low coronal CME signatures and magnetic clouds; Coronal mass ejections in the heliosphere; and Coronal mass ejections and space weather. Primary authorship is indicated at the beginning of each section. Title: A synoptic view of solar transient evolution in the inner heliosphere using the Heliospheric Imagers on STEREO Authors: Davies, J. A.; Harrison, R. A.; Rouillard, A. P.; Sheeley, N. R.; Perry, C. H.; Bewsher, D.; Davis, C. J.; Eyles, C. J.; Crothers, S. R.; Brown, D. S. Bibcode: 2009GeoRL..36.2102D Altcode: By exploiting data from the STEREO/heliospheric imagers (HI) we extend a well-established technique developed for coronal analysis by producing time-elongation plots that reveal the nature of solar transient activity over a far more extensive region of the heliosphere than previously possible from coronagraph images. Despite the simplicity of these plots, their power in demonstrating how the plethora of ascending coronal features observed near the Sun evolve as they move antisunward is obvious. The time-elongation profile of a transient tracked by HI can, moreover, be used to establish its angle out of the plane-of-the-sky an illustration of such analysis reveals coronal mass ejection material that can be clearly observed propagating out to distances beyond 1AU. This work confirms the value of the time-elongation format in identifying/characterising transient activity in the inner heliosphere, whilst also validating the ability of HI to continuously monitor solar ejecta out to and beyond 1AU. Title: Predicting CME activity, do the Heliospheric Imagers hold any clues? Authors: Davis, C. J.; Harrison, R. A. Bibcode: 2008AGUFMSH11A..06D Altcode: Inspection of images from the STEREO Heliospheric Imagers shows a remarkable amount of structure in the solar wind and streamer belt, even at times of little or no solar activity. A subset of these images were scrutinised for changes in this solar wind structure ahead of coronal mass ejections in an attempt to verify if these changes were associated with ensuing mass ejections and whether these changes could be used to identify the processes by which these mass ejections were triggered. Title: Meeting contribution: The STEREO solar mission Authors: Harrison, R. Bibcode: 2008JBAA..118..347H Altcode: No abstract at ADS Title: First imaging of corotating interaction regions using the STEREO spacecraft Authors: Rouillard, A. P.; Davies, J. A.; Forsyth, R. J.; Rees, A.; Davis, C. J.; Harrison, R. A.; Lockwood, M.; Bewsher, D.; Crothers, S. R.; Eyles, C. J.; Hapgood, M.; Perry, C. H. Bibcode: 2008GeoRL..3510110R Altcode: Plasma parcels are observed propagating from the Sun out to the large coronal heights monitored by the Heliospheric Imagers (HI) instruments onboard the NASA STEREO spacecraft during September 2007. The source region of these out-flowing parcels is found to corotate with the Sun and to be rooted near the western boundary of an equatorial coronal hole. These plasma enhancements evolve during their propagation through the HI cameras' fields of view and only becoming fully developed in the outer camera field of view. We provide evidence that HI is observing the formation of a Corotating Interaction Region (CIR) where fast solar wind from the equatorial coronal hole is interacting with the slow solar wind of the streamer belt located on the western edge of that coronal hole. A dense plasma parcel is also observed near the footpoint of the observed CIR at a distance less than 0.1AU from the Sun where fast wind would have not had time to catch up slow wind. We suggest that this low-lying plasma enhancement is a plasma parcel which has been disconnected from a helmet streamer and subsequently becomes embedded inside the corotating interaction region. Title: Observations of Dust Impacts from STEREO Authors: Howard, R. A.; St Cyr, C.; Kaiser, M.; Goetz, K.; Harrison, R. A. Bibcode: 2008AGUSM.P34A..07H Altcode: The NASA STEREO mission was launched in October, 2006. The two STEREO spacecraft are in heliospheric orbit about 1 AU from the Sun, one drifting ahead of Earth and one drifting behind. In order to achieve the drift the Ahead spacecraft is slightly closer to the Sun than Earth and the Behind spacecraft is slightly further from the Sun. Since soon after launch, the optical (STEREO/SECCHI) and radio (STEREO/SWAVES) remote sensing instruments began observing transients which are being interpreted as impacts of dust particles. There are three different types of observations: (1) transients in the potential measured by the SWAVES radio experiment, (2) optical tracks in the SECCHI (COR1, COR2 and HI-1) images and (3) results from the on-board image scrubbing algorithm in HI-1. There is some agreement in the onset times between the three detection methods, but not always. The frequency of events detected by STEREO-A and STEREO-B, which are now about 45 degrees apart, is quite different. We will present the observations and our preliminary interpretation. 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: Heliospheric Images of the Solar Wind at Earth Authors: Sheeley, N. R., Jr.; Herbst, A. D.; Palatchi, C. A.; Wang, Y. -M.; Howard, R. A.; Moses, J. D.; Vourlidas, A.; Newmark, J. S.; Socker, D. G.; Plunkett, S. P.; Korendyke, C. M.; Burlaga, L. F.; Davila, J. M.; Thompson, W. T.; St. Cyr, O. C.; Harrison, R. A.; Davis, C. J.; Eyles, C. J.; Halain, J. P.; Wang, D.; Rich, N. B.; Battams, K.; Esfandiari, E.; Stenborg, G. Bibcode: 2008ApJ...675..853S Altcode: During relatively quiet solar conditions throughout the spring and summer of 2007, the SECCHI HI2 white-light telescope on the STEREO B solar-orbiting spacecraft observed a succession of wave fronts sweeping past Earth. We have compared these heliospheric images with in situ plasma and magnetic field measurements obtained by near-Earth spacecraft, and we have found a near perfect association between the occurrence of these waves and the arrival of density enhancements at the leading edges of high-speed solar wind streams. Virtually all of the strong corotating interaction regions are accompanied by large-scale waves, and the low-density regions between them lack such waves. Because the Sun was dominated by long-lived coronal holes and recurrent solar wind streams during this interval, there is little doubt that we have been observing the compression regions that are formed at low latitude as solar rotation causes the high-speed wind from coronal holes to run into lower speed wind ahead of it. Title: SECCHI Observations of the Sun's Garden-Hose Density Spiral Authors: Sheeley, N. R., Jr.; Herbst, A. D.; Palatchi, C. A.; Wang, Y. -M.; Howard, R. A.; Moses, J. D.; Vourlidas, A.; Newmark, J. S.; Socker, D. G.; Plunkett, S. P.; Korendyke, C. M.; Burlaga, L. F.; Davila, J. M.; Thompson, W. T.; St. Cyr, O. C.; Harrison, R. A.; Davis, C. J.; Eyles, C. J.; Halain, J. P.; Wang, D.; Rich, N. B.; Battams, K.; Esfandiari, E.; Stenborg, G. Bibcode: 2008ApJ...674L.109S Altcode: The SECCHI HI2 white-light imagers on the STEREO A and B spacecraft show systematically different proper motions of material moving outward from the Sun in front of high-speed solar wind streams from coronal holes. As a group of ejections enters the eastern (A) field of view, the elements at the rear of the group appear to overrun the elements at the front. (This is a projection effect and does not mean that the different elements actually merge.) The opposite is true in the western (B) field; the elements at the front of the group appear to run away from the elements at the rear. Elongation/time maps show this effect as a characteristic grouping of the tracks of motion into convergent patterns in the east and divergent patterns in the west, consistent with ejections from a single longitude on the rotating Sun. Evidently, we are observing segments of the "garden-hose" spiral made visible when fast wind from a low-latitude coronal hole compresses blobs of streamer material being shed at the leading edge of the hole. Title: The relationship between EUV dimming and coronal mass ejections. I. Statistical study and probability model Authors: Bewsher, D.; Harrison, R. A.; Brown, D. S. Bibcode: 2008A&A...478..897B Altcode: Aims:There have been many studies of extreme-ultraviolet (EUV) dimming in association with coronal mass ejection (CME) onsets. However, there has never been a thorough statistical study of this association, covering appropriate temperature ranges. Thus, we make use of a large campaign database utilising the Coronal Diagnostic Spectrometer (CDS) and the Large Angle and Spectrometric COronagraph (LASCO) both on the SOlar and Heliospheric Observatory (SOHO) to associate dimming events detected at 1 and 2 million K with CME activity. The aim is to confirm whether the dimming-CME association is real or not. This in turn will confirm whether special attention should be paid to the EUV dimming in the pre-eruption and eruption periods to study the CME onset process itself.
Methods: The CDS CME onset campaign data for Mg IX and FE XVI observations on the solar limb are used to compare to LASCO event lists over a period from 1998 to 2005. Dimming events are identified and the physical extent explored, whilst comparing the events to overlying CME activity.
Results: For the identified dimming regions we have shown strong associations with CME onsets, with up to 55% of the dimming events being associated with CME activity. This is compared to the random case where up to 47% of the dimming regions are expected to be associated with CMEs. We have also shown that up to 84% of CMEs associated with our data can be tracked back to dimming regions. This compares to a random case of up to 58%.
Conclusions: These results confirm the CME-EUV dimming association, using a statistical analysis for the first time. We discuss the repercussions for the study of CME onsets, i.e. analysis of the dimming regions and the periods up to such dimming may be key to understanding the pre-CME onset plasma processes. The results stress that one emission line may not be sufficient for associating dimming regions with CMEs.

Appendix A is only available in electronic form at http://www.aanda.org Title: First Imaging of Coronal Mass Ejections in the Heliosphere Viewed from Outside the Sun Earth Line Authors: Harrison, Richard A.; Davis, Christopher J.; Eyles, Christopher J.; Bewsher, Danielle; Crothers, Steve R.; Davies, Jackie A.; Howard, Russell A.; Moses, Daniel J.; Socker, Dennis G.; Newmark, Jeffrey S.; Halain, Jean-Philippe; Defise, Jean-Marc; Mazy, Emmanuel; Rochus, Pierre; Webb, David F.; Simnett, George M. Bibcode: 2008SoPh..247..171H Altcode: We show for the first time images of solar coronal mass ejections (CMEs) viewed using the Heliospheric Imager (HI) instrument aboard the NASA STEREO spacecraft. The HI instruments are wide-angle imaging systems designed to detect CMEs in the heliosphere, in particular, for the first time, observing the propagation of such events along the Sun - Earth line, that is, those directed towards Earth. At the time of writing the STEREO spacecraft are still close to the Earth and the full advantage of the HI dual-imaging has yet to be realised. However, even these early results show that despite severe technical challenges in their design and implementation, the HI instruments can successfully detect CMEs in the heliosphere, and this is an extremely important milestone for CME research. For the principal event being analysed here we demonstrate an ability to track a CME from the corona to over 40 degrees. The time - altitude history shows a constant speed of ascent over at least the first 50 solar radii and some evidence for deceleration at distances of over 20 degrees. Comparisons of associated coronagraph data and the HI images show that the basic structure of the CME remains clearly intact as it propagates from the corona into the heliosphere. Extracting the CME signal requires a consideration of the F-coronal intensity distribution, which can be identified from the HI data. Thus we present the preliminary results on this measured F-coronal intensity and compare these to the modelled F-corona of Koutchmy and Lamy (IAU Colloq.85, 63, 1985). This analysis demonstrates that CME material some two orders of magnitude weaker than the F-corona can be detected; a specific example at 40 solar radii revealed CME intensities as low as 1.7×10−14 of the solar brightness. These observations herald a new era in CME research as we extend our capability for tracking, in particular, Earth-directed CMEs into the heliosphere. Title: Solar Mass Ejection Studies - Coordinated Investigation Programme 1 Authors: Harrison, Richard; Bewsher, Danielle; Davis, Chris; Breen, Andy; Webb, David Bibcode: 2008cosp...37.1181H Altcode: 2008cosp.meet.1181H IHY Coordinated Investigation Programme number 1 is concerned with solar coronal mass ejections (CMEs). It has two parts, specifically, (i) studies of the onset of CMEs through multispacecraft observations of the source regions of CMEs, in particular including the development of spectroscopic observations in the extreme-ultraviolet, and (ii) studies of interplanetary CMEs, especially those directed towards Earth utilising multiple spacecraft including the new STEREO mission. The effort has been done in hindsight, i.e. ‘post-event' campaigns are defined based on particular observation scenarios or on the acquisition of good quality data-sets and a range of research topics have been addressed. Here, we summarise the sub-campaigns and their results - but we also ask how these efforts have been enhanced by the IHY activities. Title: Interplanetary Coronal Mass Ejections Authors: Harrison, Richard; Davis, Chris; Davies, Jackie; Eyles, Chris; Crothers, Steve; Bewsher, Danielle Bibcode: 2008cosp...37.1182H Altcode: 2008cosp.meet.1182H With the new STEREO spacecraft and the Heliospheric Imager instruments we are now able to make the most basic observations of ICMEs, in particular those directed towards Earth and to make comparisons to the interpretations of in-situ data which have been used over the years to investigate the structure and evolution of ICMEs and of their connectivity to the Sun. Thus, we present evidence which confirms the magnetic structure of ICMEs as they propagate to Earth-like distances, and discuss how that structure evolves with time. We also consider how ICMEs are connected to the Sun and in particular investigate the view that interchange reconnection represents the ‘end game' of a CME. Title: Discovery of Accelerating Plasmoids in the Tail of Comet Encke Authors: Kellett, B.; Bingham, R.; Davies, J. A.; Bewsher, D.; Harrison, R. A.; Davis, C. J.; Eyles, C. J.; Crothers, S. R. Bibcode: 2007AGUFMSH33A1087K Altcode: Comet 2P/Encke was the second comet to have its return correctly predicted (in 1819). Encke is a Jupiter-family comet with a period of 3.30 years and a perihelion distance of 0.338 AU. The interaction between cometary plasma and the solar wind plasma provides the potential for remote monitoring of the solar wind. In this regard comet Encke is potentially a very useful probe of the solar wind because of its very short orbital period and therefore large number of close approaches to the Sun. However, for this reason it is likely to have exhausted most of its reserves of ice and therefore possess a less dense plasma tail. The comet could therefore respond faster and more dynamically to solar wind variations than the tail of a more active or higher gas production comet. The Heliospheric Imager (HI) of STEREO-A (HI-1A), observed comet 2P/Encke during April, 2007. The comet was predicted to have reached perihelion on April 19th 0 UT. This paper will only consider the observations obtained by HI-1A on April 25th to 27th, 2007. At this time the comet was around 0.63 AU from Earth and 0.39 AU from the Sun. The comet was seen to exhibit a distinct "flick" of its plasma tail on April 26th and a series of "whiplash" events. However, the most interest phenomena seen was a whole series of "plasmoids" that were observed to break off from the brighter part of the tail near the nucleus and accelerate along the tail for 4-5 million kilometres down-wind of the nucleus. Title: Imaging Coronal Mass Ejections in the Heliosphere using the STEREO Heliospheric Imagers Authors: Harrison, R. A.; Davis, C. J.; Eyles, C. J.; Bewsher, D.; Crothers, S.; Davies, J. A.; Howard, R. A.; Moses, D. J.; Halain, J. Bibcode: 2007AGUFMSH42A..05H Altcode: We present images of Coronal Mass Ejections in the heliosphere, tracked from the outer corona to Earth-like distances, from the first months of the scientific operation of the Heliospheric Imagers (HI) aboard the NASA STEREO spacecraft. The HI instruments are wide-angle imaging systems designed to detect CMEs in the heliosphere, in particular, for the first time, observing the propagation of such events along the Sun-Earth line. These early results show that despite severe technical challenges in their design and implementation, the HI instruments can successfully detect CMEs in the heliosphere and this is an extremely important milestone for CME research. Among the early results, we show a number of CME events, demonstrating the ability to extract the F-coronal intensity distribution, and to track a CME from the corona to the Earth. Early investigations of the velocity profiles of CMEs as they propagate through the heliosphere and of their basic structure will be presented. Title: Solar effects at Earth as observed by the STEREO Heliospheric Imagers Authors: Rouillard, A.; Davis, C. J.; Harrison, R. A.; Davies, J. A.; Bewsher, D.; Crothers, S. R.; Eyles, C. J. Bibcode: 2007AGUFMSH51B..05R Altcode: The twin STEREO spacecraft each carry a Heliospheric Imager. These wide angle cameras have provided the first ever observations of Earth directed events from a position outside the Sun-Earth line. We present combined observations taken with the instruments onboard STEREO, SOHO and ACE spacecraft as we track the progress of material through the heliosphere. At Earth, the impact of the solar wind on the Earth's atmosphere is tracked by the Cluster satellites and EISCAT radars. Title: STEREO SECCHI Observations of Space Debris: Are They Associated with S/WAVES Dust Detections? Authors: St. Cyr, O. C.; Howard, R. A.; Wang, D.; Thompson, W. T.; Harrison, R. A.; Kaiser, M. L. Bibcode: 2007AGUFMSH33A1092S Altcode: White-light coronagraphs are optimized to reject stray light in order to accomplish their primary science objective - - the observation of coronal mass ejections (CMEs) and the corona. Because they were designed to detect these faint signals while pointing at the Sun, many spacebased coronagraphs in the past (Skylab, SMM, SOHO) have detected "debris" apparently associated with the vehicle. These appear to be sunlit particles very near the front of the telescope aperture (~meters). In at least one case, these earlier debris sightings were interpreted as deteriorating insulation from the thermal blankets on the spacecraft (St. Cyr and Warner, 1991ASPC...17..126S); and for the earlier Sklyab observations, the sightings were believed to be associated with water droplets (Eddy, "A New Sun: The Solar Results from Skylab", NASA SP-402, p119, 1979.) The STEREO SECCHI suite of white-light coronagraphs represents the most recent instantations of these specialized instruments, and for the first time we are able to track CMEs from their initiation at the Sun out to 1 A.U. Since observations commenced, the SECCHI white-light telescopes have been sporadically detecting debris particles. Most of the detections are individual or small numbers of bright objects in the field which therefore do not affect the primary science goals of the mission. But on several occasions in the eight months' of observation there have been "swarms" of these bright objects which completely obscure the field of view of one or more instrument for a brief period of time. Here we report on the intriguing possibility that the SECCHI debris sightings represent particles of thermal insulation, ejected from the spacecraft by interplanetary dust impacts. Because of the large field of view and high duty cycle of the Heliospheric Imagers on STEREO, we may be able to demonstrate that some of these have also been detected by STEREO S/WAVES as sporadic plasma emissions. Title: A 3D view of coronal mass ejections in interplanetary space Authors: Breen, A. R.; Dorrian, G. D.; Bisi, M. M.; Davis, C. J.; Fallows, R. A.; Morgan, H.; Harrison, R. A. Bibcode: 2007AGUFMSH33A1081B Altcode: Ground-based measurements of interplanetary scintillation (IPS) have been used to study the solar wind for many years, but interpretation of the results has always been rendered more difficult by uncertainty about the electron density distribution along the extended line-of-sight from radio source to antenna. This has been particularly marked in the case of Earth-directed coronal mass ejections (CMEs). The launch of the STEREO spacecraft, with its Heliospheric Imager (HI) instruments, provides us with the first detailed view of structures in the Sun-Earth line, revealing the motion of large-scale density structures, and greatly reducing the uncertainties in interpreting IPS observations of the speeds of small-scale irregularities embedded within the larger structures. In this poster we present results from a co-ordinated programme of measurements which brings together STEREO HI and two different IPS experiments. We consider two events, one from 2005 in which we use a combination of long-baseline IPS measurements from EISCAT and MERLIN, tomographically-reconstructed 3D density distributions from STELab IPS observations, and SOHO EIT and LASCO images to track the development of an Earth-directed CME. We discuss the remaining uncertainties in this approach and the ways in which STEREO HI images would have assisted with the analysis. In the second event we combine STEREO HI observations of structures in the solar wind with IPS measurements of solar wind speed from EISCAT and MERLIN and tomographic reconstructions of 3D structure. We discuss the results and present suggestions for future co-ordinated campaigns. Title: First Direct Observation of the Interaction between a Comet and a Coronal Mass Ejection Leading to a Complete Plasma Tail Disconnection Authors: Vourlidas, Angelos; Davis, Chris J.; Eyles, Chris J.; Crothers, Steve R.; Harrison, Richard A.; Howard, Russell A.; Moses, J. Daniel; Socker, Dennis G. Bibcode: 2007ApJ...668L..79V Altcode: This a discovery report of the first direct imaging of the interaction a comet with a coronal mass ejection (CME) in the inner heliosphere with high temporal and spatial resolution. The observations were obtained by the Sun-Earth Connection Coronal and Heliospheric Investigation (SECCHI) Heliospheric Imager-1 (HI-1) aboard the STEREO mission. They reveal the extent of the plasma tail of comet 2P/Encke to unprecedented lengths and allow us to examine the mechanism behind a spectacular tail disconnection event. Our preliminary analysis suggests that the disconnection is driven by magnetic reconnection between the magnetic field entrained in the CME and the interplanetary field draped around the comet and not by pressure effects. Further analysis is required before we can conclude whether the reconnection occurs on the day side or on the tail side of the comet. However, the observations offer strong support to the idea that large-scale tail disconnections are magnetic in origin. The online movie reveals a wealth of interactions between solar wind structures and the plasma tail beyond the collision with the CME. Future analyses of this data set should provide critical insights on the structure of the inner heliosphere. Title: In-orbit verification, calibration, and performance of the Heliospheric Imager on the STEREO mission Authors: Eyles, Chris; Davis, Chris; Harrison, Richard; Waltham, Nick; Halain, Jean-Philippe; Mazy, Emmanuel; Defise, Jean-Marc; Howard, Russ; Moses, Dan; Newmark, Jeff; Plunkett, Simon Bibcode: 2007SPIE.6689E..07E Altcode: 2007SPIE.6689E...5E The Heliospheric Imager (HI) forms part of the SECCHI suite of instruments aboard the two NASA STEREO spacecraft which were launched successfully from Cape Canaveral AFB on 25 Oct 2006 (26 Oct UTC). Following lunar swingby's on 15 Dec and 21 Jan respectively, the two spacecraft were placed in heliocentric orbits at approximately 1 AU - one leading and one lagging the Earth, with each spacecraft separating from the Earth by 22.5° per year. Each HI instrument comprises two wide-angle optical cameras - HI-1 and HI-2 have 20° and 70° fields-of-view which are off-pointed from the Sun direction by 14.0° and 53.7° respectively, with the optical axes pointed towards the ecliptic plane. In this way the cameras will for the first time provide stereographic images of the solar corona, and in particular of Coronal Mass Ejections (CMEs) as they propagate outwards through interplanetary space towards the Earth and beyond. The wide-field coverage of HI enables imaging of solar ejecta from 15 to about 330 solar radii whilst the other SECCHI instruments (2 coronagraphs and an EUV imager) provide coverage from the lower corona out to 15 solar radii. This paper briefly reviews the design and performance requirements for the instrument. The various activation, checkout and calibration activities before and after opening the instrument's protective cover or door (instrument 'first-light') are then described and it is shown that the instrument has met the design requirements, including CCD and camera imaging performance, correction for shutterless operation of the cameras, straylight rejection and thermal requirements. It is demonstrated from observations of a CME event on 24-25 Jan 2007 that the instrument is capable of detecting CMEs at an intensity of 1% of the coronal background. Lessons learnt during the design, development and in-orbit operation of the instrument are discussed. Title: First Combined Observations Of Cmes By The Lasco Coronagraphs, Smei And The Stereo Secchi Heliospherical Imagers Authors: Webb, David F.; Howard, R. A.; Morrill, J. S.; Harrison, R. A.; Eyles, C. J.; Howard, T. A.; Kuchar, T. A.; Johnston, J. C. Bibcode: 2007AAS...21011906W Altcode: 2007BAAS...39..244W We report on the first combined observations of coronal mass ejections (CMEs) observed by the SOHO LASCO and STEREO SECCHI COR-2 coronagraphs, the Coriolis Solar Mass Ejection Imager (SMEI), and the SECCHI Heliospheric Imagers (HIs) on each STEREO spacecraft. STEREO was launched on 25 October 2006 and these observations were obtained during the commissioning phase. All three instruments observe density in the heliosphere via the Thomson scattering process. The LASCO and COR-2 coronagraphs observe the early development of CMEs out to 30 Rs, or about 8o. There are two HI systems on each STEREO spacecraft, HI-1 and HI-2, each with a circular field of view (fov) centered on the ecliptic plane. The HI-1 fov is 10o in radius, begins at 4o elongation, and, thus, overlaps with the LASCO fov. The HI-2 fov is 35o in radius, begins at 18.7o, and overlaps with the HI-1 fov. SMEI is an all-sky imager that detects and tracks CMEs from near the Sun at elongations > 20o to beyond 90o. Thus, the SMEI fov overlaps the outer portion of the HI-1 fov but includes nearly all of the HI-2 fov. The first HI CME observations were made by the HI-1A on 23- 28 Dec. 2006 and showed continued outflows from a limb region. One or more CMEs were observed from the east limb on 24- 25 Jan. 2007 by LASCO and HI-1A, with HI-2A and SMEI observing the outer loops into 26 Jan. We discuss the preliminary analyses of these events, including their kinematic and structural evolution through the fields of these instruments. Title: The Impact of Geometry on CME Observations Made by SEECHI Authors: Morrill, J.; Kunkel, V.; Halain, J. P.; Harrison, R. A.; Howard, R. A.; Moses, J. D.; Newmark, J.; Plunkett, S.; Socker, D.; Wang, D.; Vourlidas, A. Bibcode: 2007AGUSMSH41A..11M Altcode: Optical observations of Coronal Mass Ejections (CME's) during the past several decades have generally been confined to events observed near the sun. Although events originating from most regions of the sun can be observed, the assumption has often made that the CME is propagating in the plane-of-the-sky. This assumption is generally adequate to give lower limits of CME mass and speed. However, continuous observations of CME's are now being made from very near the solar surface to large distances from the sun by the SECCHI instrument on STEREO. When CME's are observed at great distances from the sun, plane-of-the-sky assumptions are not adequate for analysis of these events. In this presentation we will discuss some recent observations made by the SEECHI instruments and the impact of geometry on our interpretation of these events. Title: The Sun To The Earth, A Panoramic View From SECCHI: Overview Authors: Moses, John Daniel; Newmark, J.; Howard, R. A.; Plunkett, S.; Socker, D.; Wang, D.; Vourlidas, A.; Halain, J.; Harrison, R. A.; Eyles, C. J.; Davila, J.; Lemen, J.; Wuelser, J. Bibcode: 2007AAS...21011904M Altcode: 2007BAAS...39..244M The Sun Earth Connection Coronal and Heliospheric Investigation (SECCHI) is the remote sensing component of the STEREO mission to explore the source, initiation, and propagation through the heliosphere of Coronal Mass Ejections (CMEs). To achieve this goal, SECCHI must continuously observe CMEs from two different perspectives beginning with the pre-event coronal configuration and ending with the propagation of the event out of the inner heliosphere. Thus, each of the two STEREO observatories carries a suite of SECCHI telescopes with 5 different fields of view providing an uninterrupted view of coronal and Heliospheric phenomena from the solar chromosphere to 1 AU. This is the first panoramic view of the inner heliosphere dedicated to observing the spatial and temporal scales characteristic of CMEs at elongation angles from 0 to almost 90 degrees.

We present first results from the SECCHI imaging suite with emphasis on the unprecedented panoramic views of the heliosphere. We show direct observations of CMEs and the solar wind from initiation on the Sun throughout the inner heliosphere to 1 AU. The SECCHI suite performance exceeds that necessary to achieve the Level 1 STEREO science objectives. Thus, as the STEREO spacecraft separate to provide views from different directions we can anticipate breakthrough observations for issues currently unresolved by plane-of-sky projections through optically thin structures.

The most current information on SECCHI can be obtained from the STEREO mission website at http://stereo.gsfc.nasa.gov and the SECCHI website at http://secchi.nrl.navy.mil. The NRL participation in the STEREO mission is supported by NASA under S-13631-Y, and by the Office of Naval Research. 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: Discovery of the Atomic Iron Tail of Comet MCNaught Using the Heliospheric Imager on STEREO Authors: Fulle, M.; Leblanc, F.; Harrison, R. A.; Davis, C. J.; Eyles, C. J.; Halain, J. P.; Howard, R. A.; Bockelée-Morvan, D.; Cremonese, G.; Scarmato, T. Bibcode: 2007ApJ...661L..93F Altcode: In 2007 January, at the heliocentric distance r<0.3 AU, comet McNaught 2006P1 became the brightest comet since C/Ikeya-Seki 1965S1 and was continuously monitored by space-based solar observatories. We provide strong evidence that an archlike tail observed by the Heliospheric Imager aboard the STEREO spacecraft is the first ever detected tail composed of neutral Fe atoms. We obtain an Fe lifetime τ=(4.1+/-0.4)×104 s at r=0.25 AU, in agreement with theoretical predictions of the photoionization lifetime. The expected dust temperature is inconsistent with iron sublimation, suggesting that Fe atoms are coming from troilite evaporation. 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: The Sun To The Earth, A Panoramic View From SECCHI: CME Observations Through The Inner Heliosphere Authors: Newmark, Jeffrey; Moses, J. D.; Howard, R. A.; Plunkett, S.; Socker, D.; Wang, D.; Vourlidas, A.; Halain, J. P.; Harrison, R. A.; Eyles, C. J.; Davila, J.; Lemen, J.; Wuelser, J. P. Bibcode: 2007AAS...21011905N Altcode: 2007BAAS...39..244N The STEREO SECCHI telescope suite is returning unprecedented viewsvof the Sun and inner heliosphere. The SECCHI instruments on each of the two STEREO spacecraft are observing Coronal Mass Ejections (CMEs) from their initiation, through the corona, and into interplanetary space beyond the Earth's orbit. We present a first analysis of a CME throughout the inner heliosphere. We focus on the propagation characteristics of the CME and the morphological properties of the CME as viewed from STEREO.

This first glimpse of a CME in the heliosphere clearly demonstrates the anticipated scientific returns that future STEREO observations (at larger angular separations) of CMEs in interplanetary space will provide.

The most current information can be obtained on the STEREO mission website at http://stereo.gsfc.nasa.gov and the SECCHI website at http://secchi.nrl.navy.mil. The NRL participation on SECCHI is supported by NASA under S-13631-Y, and by the Office of Naval Research. Title: Commission 10: Solar Activity Authors: Melrose, Donald B.; Klimchuk, James A.; Benz, A. O.; Craig, I. J. D.; Gopalswamy, N.; Harrison, R. A.; Kozlovsky, B. Z.; Poletto, G.; Schrijver, K. J.; van Driel-Gesztelyi, L.; Wang, J. -X. Bibcode: 2007IAUTA..26...75M Altcode: Commission 10 aims at the study of various forms of solar activity, including networks, plages, pores, spots, fibrils, surges, jets, filaments/prominences, coronal loops, flares, coronal mass ejections (CMEs), solar cycle, microflares, nanoflares, coronal heating etc., which are all manifestation of the interplay of magnetic fields and solar plasma. Increasingly important is the study of solar activities as sources of various disturbances in the interplanetary space and near-Earth "space weather".Over the past three years a major component of research on the active Sun has involved data from the RHESSI spacecraft. This review starts with an update on current and planned solar observations from spacecraft. The discussion of solar flares gives emphasis to new results from RHESSI, along with updates on other aspects of flares. Recent progress on two theoretical concepts, magnetic reconnection and magnetic helicity is then summarized, followed by discussions of coronal loops and heating, the magnetic carpet and filaments. The final topic discussed is coronal mass ejections and space weather.The discussions on each topic is relatively brief, and intended as an outline to put the extensive list of references in context.The review was prepared jointly by the members of the Organizing Committee, and the names of the primary contributors to the various sections are indicated in parentheses. Title: Searching for solar clouds in interplanetary space Authors: Harrison, Richard; Davis, Chris; Eyles, Chris; Halain, Jean-Philippe; Howard, Russ Bibcode: 2007SpReT.168...25H Altcode: No abstract at ADS Title: T he Solar Orbiter Payload Working Group: Remote Sensing Authors: Harrison, R. Bibcode: 2007ESASP.641E...2H Altcode: The activities of the Solar Orbiter Payload Working Group, covering remote sensing issues are outlined in this report. Solar Orbiter faces many challenges mainly due to its unusual orbit, encountering extreme thermal and particle environments, and demanding low mass and autonomous operation whilst providing major advances in solar observation. Procedures for the assessment of challenges and subsequent recommendations to ESA are outlined, as well as the activities relating to the Payload Definition Document. Title: A benchmark event sequence for mass ejection onset studies. A flare associated CME with coronal dimming, ascending pre-flare loops and a transient cool loop Authors: Harrison, R. A.; Bewsher, D. Bibcode: 2007A&A...461.1155H Altcode: Aims:In this study, we report on the spectroscopic observations of a particularly well-observed flare and coronal mass ejection (CME) event sequence which we feel can be used as a benchmark study for CME onsets.
Methods: Specifically, we report on a set of extreme-ultraviolet (EUV) spectroscopic observations using the Solar and Heliospheric Observatory (SOHO) to determine features of the CME onset process revealed through the analysis of plasma at different temperatures.
Results: The flare which occurred on the north-western limb was associated with a large CME. The event in question showed evidence for pre-flare ascending loops containing 1-2 million K plasma, which disappeared just prior to the flare. This disappearance is interpreted as coronal dimming, and it appears to coincide with the projected mass ejection onset time. In addition, a discrete, short-lived coronal loop containing plasma at transition region temperatures was detected just prior to this eruption. This loop displayed mass motion, along flux tubes, with oppositely directed flows. The nature and timing of this transient loop suggest a close relationship between it and the eruption process. Examinations of the timing and topology, which extend previous studies considerably, are found to be consistent with the mass ejection onset interpretation of Zhang and co-workers.
Conclusions: .The clarity of this event sequence suggests that we should regard it as a benchmark in studies of the mass ejection onset process. Title: Extreme-Ultraviolet Spectrometer For Solar Orbiter Authors: Harrison, R.; Sawyer, E. Bibcode: 2007ESASP.641E..35H Altcode: An Exteme-Ultraviolet Spectrometer (EUS) instrument has always been a key component of the Solar Orbiter strawman payload. Such an instrument is required to provide plasma diagnostic capabilities in support of the goals of Orbiter. We describe the instrument concept for an EUS instrument on behalf of an established consortium. We outline the basic optical design approach and the strategy for catering for the extreme thermal, particle environment and mechanical issues. Reference is made to a number of papers in this issue and elsewhere which provide the details of the proposed instrument and we concentrate here on the instrument strategy. Title: Book Review: Book review Authors: Harrison, Richard Bibcode: 2007SpReT.170...61H Altcode: No abstract at ADS 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: Bursting the Solar Bubble: The Flare-Coronal Mass Ejection Relationship Authors: Harrison, Richard Bibcode: 2006GMS...165...73H Altcode: One of the fundamental problems in solar physics research today is our understanding of the flare-coronal mass ejection (CME) relationship. On the face of it, a basic investigation of the association between the two most energetic transient phenomena in the solar system would appear to be a relatively simple prospect. However, observational limitations in particular have served to limit our understanding of the flare-CME phenomenon, and thus our understanding of the CME onset mechanisms. Here, we review briefly flare-CME research prior to the Solar and Heliospheric Observatory (SOHO) era, and, through a series of illustrations of recent observations, and reference to several new directions of investigation, summarise our current thinking regarding the flare-CME scenario and the CME onset. Title: 10 Years of CME Onset Studies with SOHO/CDS Authors: Bewsher, D.; Harrison, R. A. Bibcode: 2006ESASP.617E..21B Altcode: 2006soho...17E..21B No abstract at ADS Title: Science Plans for the International Heliophysical Year Authors: Davila, J. M.; Gopalswamy, N.; Harrison, R. A.; Stamper, R.; Briand, C.; Potgieter, M. S. Bibcode: 2006AGUSM.U34A..04D Altcode: On October 4, 1957, only 53 years after the beginning of flight in Kitty Hawk, the launch of Sputnik 1 marked the beginning of the space age; as mankind took the first steps to leaving the protected environment of Earth's atmosphere. Discovery of the radiation belts, the solar wind, and the structure of Earth's magnetosphere prepared the way for the inevitable human exploration to follow. Soon, Cosmonauts and Astronauts orbited Earth, and then in 1969, Astronauts landed on the Moon. Today a similar story is unfolding, the spacecraft Voyager has crossed the termination shock, and will soon leave the heliosphere. For the first time, man will begin to explore the local interstellar medium. It is inevitable that, during the next 50 years, exploration of the solar system including the Moon, Mars and the outer planets will be the focus of the space program, and like 50 years ago, unmanned probes will lead the way, followed by human exploration. The International Geophysical Year (IGY) of 1957, a broad-based and all-encompassing effort to push the frontiers of geophysics, resulted in a tremendous increase of knowledge in space physics, Sun-Earth Connection, planetary science and the heliosphere in general. Now, 50 years later, we have the unique opportunity to further advance our knowledge of the global heliosphere and its interaction with the interstellar medium through the International Heliophysical Year (IHY) in 2007, and to raise public awareness of space physics. This presentation will focus on global science planning efforts and campaigns for all participating IHY nations. Title: IHY Science and Organization in Europe Authors: Bougeret, J. -L.; Briand, C.; Bonet Navaro, J. A.; Breen, A.; Candidi, M.; Georgevia, K.; Harrison, R.; Marsden, R.; Schmieder, B.; von Steiger, R. Bibcode: 2006cosp...36.3226B Altcode: 2006cosp.meet.3226B We present the scientific and organizational approach to the International Heliophysical Year in Europe A summary is given of the First European General Assembly of the IHY that was held in Paris in January 2006 Initiatives and expected returns are described Title: The SECCHI Experiment on the STEREO Mission Authors: Howard, R.; Moses, D.; Vourlidas, A.; Davila, J.; Lemen, J.; Harrison, R.; Eyles, C.; Defise, J. -M.; Bothmer, V.; Ravet, M. -F.; Secchi Team Bibcode: 2006cosp...36..870H Altcode: 2006cosp.meet..870H 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 Title: EUV and UV imaging and spectroscopy from space Authors: Harrison, Richard A. Bibcode: 2005pmds.book..125H Altcode: No abstract at ADS Title: 2007: International Heliophysical Year Authors: Harrison, Richard; Breen, Andy; Bromage, Barbara; Davila, Joe Bibcode: 2005A&G....46c..27H Altcode: In 1957 a programme of international research was organized as the International Geophysical Year (IGY) to study global phenomena of the Earth and geospace. This programme was a follow-on to the International Polar Years in 1882-83 and 1932-33. The IGY involved about 60 000 scientists from 66 nations, working at thousands of stations, from pole to pole. There had never been anything like it before. The 50th anniversary of IGY will occur in 2007. Plans are well under way to organize an international programme of scientific collaboration for this time period to focus not just on the Earth but extending our horizons to the heliosphere, including the Sun, and thus including the drivers of geophysical processes, and making use of the fleet of spacecraft and numerous ground-based systems in place. This programme is called the International Heliophysical Year. Title: The widths of vacuum-ultraviolet spectral lines in the equatorial solar corona observed with CDS and SUMER Authors: Wilhelm, K.; Fludra, A.; Teriaca, L.; Harrison, R. A.; Dwivedi, B. N.; Pike, C. D. Bibcode: 2005A&A...435..733W Altcode: Observations of the solar equatorial corona between heights of 36 Mm and 184 Mm above the limb obtained by the SOHO spectrometers CDS and SUMER in December 2003 are presented and discussed with special emphasis on the widths of the spectral lines Mg x at 62.50 nm, Al xi at 55.00 nm and 56.82 nm, Ca x at 55.78 nm, and Si xi at 58.09 nm. SUMER observed, in addition, the lines Mg x 60.98 nm, Ca x 57.40 nm, Fe xii 124.20 nm, Fe xvii 115.31 nm, and Ca xiii 113.37 nm. The Si xii 52.11 nm line was only observed by CDS. A different behaviour of the line width of Mg x 62.50 nm as a function of height above the limb had been found in studies carried out independently with both instruments at different times. It is the aim of this joint investigation to (a) study instrumental effects on line-width results; and (b) provide a thorough analysis of line profiles with altitude for the new campaign. Title: Coronal and Heliospheric Science Opportunities with the SECCHI Heliospheric Imager Authors: Moses, J.; Socker, D.; Eyles, C.; Harrison, R.; Defise, J.; Howard, R.; Rochus, P.; Waltham, N.; Simnett, G.; Newmark, J.; Halain, J.; Mapson-Menard, H.; Mazy, E.; Davis, C. Bibcode: 2005AGUSMSH51D..02M Altcode: The Heliospheric Imager (HI) is part of the SECCHI suite of instruments on-board the two STEREO spacecrafts. The two HI instruments will provide stereographic image pairs of solar coronal plasma and coronal mass ejections (CME) over a wide field of view (85 degrees), with an inner field limit of approximately 13 solar radii. These observations compliment the 15 solar radii field of view of the solar corona obtained by the other SECCHI instruments to provide unbroken coverage of the solar corona and heliosphere from the Sun to the Earth. The as-built characteristics of the HI will be presented along with the current data reduction and analysis approach. The constraints that HI observations place on models of CME propagation in the interplanetary medium will be discussed. Title: Planning for SECCHI Observations of the Solar Corona and Heliosphere Authors: Plunkett, S. P.; Howard, R. A.; Rich, N. B.; Wang, D.; Harrison, R. A.; Thompson, W. T.; Wuelser, J. Bibcode: 2005AGUSMSH53A..01P Altcode: The Sun-Earth Connections Coronal and Heliospheric Investigation (SECCHI) instrument suite consists of five almost identical telescopes on each of the STEREO spacecraft. Each instrument suite includes an extreme ultraviolet disk imager (EUVI), two coronagraphs (COR1 and COR2) and two heliospheric imagers (HI1 and HI2) that will image the corona and heliosphere to distances beyond the Earth's orbit. SECCHI observations will consist of a synoptic program optimized to provide simultaneous identical images for stereoscopic viewing of coronal and heliospheric structures from both STEREO spacecraft, and special observations that can be tailored to meet specific science objectives. This paper will describe the observational capabilities of the SECCHI instruments, and will discuss the operational resources available and constraints on observations at various stages of the mission. Title: EUV spectroscopy for Solar Orbiter Authors: Harrison, R. A. Bibcode: 2005AdSpR..36.1415H Altcode: Building on the success of EUV/UV spectroscopic studies from the SOHO mission in particular, a next generation spectroscopic study of the Sun is included in plans for Solar Orbiter. The combination of close-up and out of ecliptic observation provides unique possibilities for solar plasma diagnostics and these are outlined here. Technical challenges and the instrumental requirements for such an instrument aboard Orbiter are described in detail. Title: Natural disasters — Are we doing enough? Authors: Harrison, Richard Bibcode: 2005CIBu..162...47H Altcode: 2005SpReT.162...47H No abstract at ADS Title: STEREO/HI from near-Earth objects to 3D comets Authors: Davis, C. J.; Harrison, R. A. Bibcode: 2005AdSpR..36.1524D Altcode: Scientific objectives are being compared with hardware capabilities in order to fully exploit the capabilities of the STEREO heliospheric imager (HI). This has involved detailed image simulation work and efforts to produce a set of observational plans to tackle specific scientific questions. While the primary mission for this instrument is to study the development and propagation of coronal mass ejections, several additional novel science studies have been proposed. These include; the detection and study of near-Earth objects and the imaging of comets in three dimensions. Identifying all potential new uses of HI before launch will enable us to anticipate user requirements and provide the necessary data products and operations tools. We report on the progress of the observational schemes suggested so far and invite further suggestions in order to maximize the unique capabilities of the HI. Title: Solar Orbiter—mission profile, main goals and present status Authors: Marsch, Eckart; Marsden, Richard; Harrison, Richard; Wimmer-Schweingruber, Robert; Fleck, Bernhard Bibcode: 2005AdSpR..36.1360M Altcode: The main goals and present status of the Solar Orbiter mission are briefly described. solar orbiter will determine in situ the properties of fields and particles in the unexplored near-Sun heliosphere in three dimensions, investigate remotely the fine-scale structures and events in the magnetically coupled layers of the Sun’s atmosphere, identify through near corotation the links between activity on the solar surface and the resulting evolution of the inner heliosphere, and observe from relatively high latitudes the polar regions and equatorial corona. Some results from recent activities, such as industrial studies, payload working group meetings, science definition team meetings and ESA internal studies are briefly reviewed. Solar Orbiter is currently planned for launch in October 2013. Title: Preface Authors: Culhane, Len; Harrison, Richard Bibcode: 2005AdSpR..36.1477C Altcode: No abstract at ADS Title: A new start Authors: Harrison, Richard; Fellous, Jean-Louis; Argent, Chris; Mendez, Mariano Bibcode: 2005CIBu..162....2H Altcode: 2005SpReT.162....2H No abstract at ADS Title: The STEREO heliospheric imager: how to detect CMEs in the heliosphere Authors: Harrison, R. A.; Davis, C. J.; Eyles, C. J. Bibcode: 2005AdSpR..36.1512H Altcode: The STEREO Heliospheric Imager is a wide-angle imaging system that will enable, for the first time, a view of Earth-directed coronal mass ejections (CMEs) in a field of view which also encompasses the Earth. Twin views from widely spaced platforms, combined with the out of Sun-Earth line perspective allow a unique and powerful tool for the study of CMEs and, particularly, Earth-directed CMEs. We outline the instrumental characteristics and image simulation studies which reveal the nature of the images we anticipate. Title: Future Solar Missions Authors: Harrison, R. A. Bibcode: 2004ESASP.575...13H Altcode: 2004soho...15...13H No abstract at ADS Title: STEREO HI - From CMEs to Near Earth Objects: a Unique View of the Heliosphere Authors: Davis, C. J.; Harrison, R. A. Bibcode: 2004AGUFMSH22A..06D Altcode: The two STEREO Heliospheric Imagers (HI) will have a unique view of the Heliosphere, with a field of view encompassing the entire Sun-Earth line. While the primary objective for HI is to detect and obtain information about the size, velocity and direction of Coronal Mass Ejections (CMEs), the sensitivity and field of view of these instruments can be exploited to extend the scientific scope of the mission. For the first time it will be possible to observe objects in this region of space in three dimensions. Simulated images are being used to determine the problems associated with observing objects from comets and asteroids through to the distribution of interplanetary dust. Title: Summary of the Solar Orbiter payload working group activities Authors: Fleck, Bernhard; Harrison, Richard A.; Marsden, Richard G.; Wimmer-Schweingruber, Robert Bibcode: 2004SPIE.5171..123F Altcode: Approved in October 2000 by ESA's Science Programme Committee as a flexi-mission, the Solar Orbiter will study the Sun and unexplored regions of the inner heliosphere from a unique orbit that brings the probe to within 45 solar radii (0.21 AU) of our star, and to solar latitudes as high as 38°. The scientific payload to be carried by the Orbiter will include a sophisticated remote-sensing package, as well as state-of-the-art in-situ instruments. Given the technical and financial constraints associated with this mission, it is essential that key technologies requiring significant development be identified as early as possible. ESA has therefore set up a Payload Working Group (PWG), made up of members of the scientific community with expertise in instrumentation of the kind envisaged for the Solar Orbiter. The tasks of the PWGs included: 1) a realistic assessment of the strawman payload, including definition of mass, size, power requirements; 2) identification of key problem areas arising as a result of the extreme thermal and radiation environments; 3) identification of necessary technological developments; and 4) provision of detailed input to a Solar Orbiter Payload Definition Document (PDD). This contribution summarizes the activities and findings by the Solar Orbiter Payload Working Group. Title: On the Coronal Mass Ejection onset and Coronal Dimming Authors: Howard, Timothy A.; Harrison, Richard A. Bibcode: 2004SoPh..219..315H Altcode: A comprehensive case and statistical study of CME onsets has been conducted on the solar limb using the CDS, LASCO and EIT instruments aboard the SOHO spacecraft. This is the first dedicated campaign to establish firmly the EUV signatures of CME onsets and is based on a series of low-corona observing campaigns made in 2002. The event database consisted of 36 multiple emission line sequences observed with CDS and the study builds, in particular, on studies of EUV coronal dimming which have been associated with CME onsets. We witness a range of dimming events in EUV coronal emission line data. Shorter events, commonly of duration < 4 hours, we find are indirectly associated with CME onsets whereas longer-duration dimmings (> 4 hours) appear to be either due to coronal evolution or rotational effects. However, for some CME onsets, where the CDS pointing was appropriate, no dimming was observed. Dimming observed in EIT typically occurred immediately after the launch of a loop or prominence, and in 5 out of 9 events there is evidence of a matter buildup within the loop before launch. A total of 10 events occurred where CDS was used to directly observe the CME footprint, but no relationship between these events was found. The results suggest that the response of the corona to a CME launch differs between the low (1.0 R≤R≤1.2 R) and middle (1.2 R<R≤2.0 R) corona regions, hence implying a difference between dimming observations conducted with different instruments. Title: Dynamics of Transition Region Blinkers Authors: Bewsher, D.; Parnell, C.; Pike, D.; Harrison, R. Bibcode: 2004ESASP.547..267B Altcode: 2004soho...13..267B Analysis of CDS data has shown that transition region blinkers and the chromosphere directly below, are preferentially more redshifted and have larger non-thermal velocities than the normal transition region and chromospheric plasma. The ranges of these enhanced velocities, however, are no larger than the typical spread of Doppler and non-thermal velocities in these regions. An overview of the Doppler and non-thermal velocities of blinkers found with CDS in the quiet Sun and active region are presented. The anticipated range of Doppler velocities of blinkers are 10 - 15 km s-1 in the quiet-Sun (10 - 20 km s-1 in active-regions) in the chromosphere (He I) and 25 - 30 km s-1 in the quiet-Sun (20 - 40 km s-1 in activeregions) in the transition region (O V). The range of non-thermal velocities of blinkers in both the quiet- Sun and active-regions are estimated to be 15 - 25 km s-1 in He I and 30 - 45 km s-1 in O V. There are more blinkers with larger Doppler and non-thermal velocities than would be expected in the whole of the chromosphere and transition region. Title: STEREO/HI: From Near-Earth Objects to 3-D Comets Authors: Davis, C.; Harrison, R. Bibcode: 2004cosp...35.2121D Altcode: 2004cosp.meet.2121D Observational methods and campaigns for using the STEREO Heliospheric Imager are being investigated. This has involved detailed image simulation work and efforts to produce a set of observational plans to tackle specific scientific questions. Most plans involve the study of the development and propagation of coronal mass ejections. However, several novel schemes are under study, for example, for the detection and study of Near-Earth Objects (NEOs) and the 3-dimensional study of comets. We report on progress in these observational schemes which serve to stress the unique capabilities of the Heliospheric Imager. Title: 1.2 Questionnaire — Summer 2004 Authors: Harrison, Richard Bibcode: 2004CIBu..160....8H Altcode: No abstract at ADS Title: EUV Spectroscopy from Solar Orbiter Authors: Harrison, R. Bibcode: 2004cosp...35..453H Altcode: 2004cosp.meet..453H Building on the success of EUV/UV spectroscopic studies from the SOHO mission in particular, a next generation spectroscopic study of the Sun is included in plans for Solar Orbiter. The combination of close-up and out of ecliptic observation provide unique possibilities for solar plasma diagnostics and these are outlined here. Technical challenges and the instrumental requirements for such an instrument aboard orbiter are described in detail. Title: Evidence for Wave Dissipation through EUV Emission Line Narrowing Authors: Harrison, R. A.; Hood, A. W.; Pike, C. D. Bibcode: 2004ESASP.547..229H Altcode: 2004soho...13..229H Using long-duration observations over closed-field, quiet Sun regions above the solar equator, evidence has been found for the narrowing of coronal emission lines with increasing altitude. This is interpreted as evidence for wave dissipation in the quiet Sun corona. Title: International heliophysical year: a program of global research continuing the tradition of previous international years Authors: Davila, Joseph M.; Poland, Arthur I.; Harrison, Richard A. Bibcode: 2004AdSpR..34.2453D Altcode: In 1957 a program of international research, inspired by the International Polar Years of 1882-1883 and 1932-1933, was organized as the International Geophysical Year (IGY) to study global phenomena of the Earth and geospace. The IGY involved about 60,000 scientists from 66 nations, working at thousands of stations from pole to pole, in an effort to obtain simultaneous, global observations on Earth and in space. There had never been anything like it before. The 50th anniversary of the International Geophysical Year will occur in 2007. We propose to organize an international program of scientific collaboration for this time period called the International Heliophysical Year (IHY). Like its predecessors, the IHY will focus on fundamental global questions of Earth science. Title: Preface Authors: Harrison, Richard A.; Argent, Chris Bibcode: 2004CIBu..160....4H Altcode: No abstract at ADS Title: The Secchi Experiment on the Stereo Mission Authors: Howard, R.; Moses, D.; Socker, D.; Cook, J.; Davila, J.; Lemen, J.; Harrison, R.; Eyles, C.; Waltham, N.; Defise, J. -M. Bibcode: 2004cosp...35.3893H Altcode: 2004cosp.meet.3893H 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 two white light coronagraphs, an extreme ultraviolet (EUV) imager, and a 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, 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. Title: The STEREO Heliospheric Imager: How to detect CMEs in the heliosphere Authors: Harrison, R.; Davis, C.; Eyles, C. Bibcode: 2004cosp...35..450H Altcode: 2004cosp.meet..450H The STEREO Heliospheric Imager is a wide-angle imaging system that will enable for the first time, a view of Earth-directed coronal mass ejections in a field of view which also encompasses the Earth. Twin views from widely spaced platforms, combined with the out of Sun-Earth line perspective allow a unique and powerful tool for the study of CMEs and, particularly, Earth-directed CMEs. We will outline the instrumental characteristics and image simulation studies which reveal the nature of the images we anticipate. Title: Preface Authors: Harrison, Richard; Argent, Chris Bibcode: 2004CIBu..161....6H Altcode: No abstract at ADS Title: A study of the unification of quiet-Sun transient-event phenomena Authors: Harrison, R. A.; Harra, L. K.; Brković, A.; Parnell, C. E. Bibcode: 2003A&A...409..755H Altcode: A number of small-scale, globally distributed solar transient event-types have been reported in the literature. Their potential role in fundamental processes in the solar atmosphere, such as coronal heating and wind acceleration, is under active investigation. However, the event-types, such as those known as blinkers, explosive events, EUV (extreme-UV) network and cell brightenings, network flares, heating events, nanoflares and EUV brightenings are basically classifications which are driven to a large extent by different observational techniques and different instruments rather than the identification of a clear differing physical phenomenon. We investigate the different instrumental and technique limitations and attempt to identify any unification of the reported quiet-Sun transient, small-scale phenomena. We find that once observational techniques have been considered, a number of the different classifications appear to be the same. This suggests that events known as blinkers, network and cell brightenings and EUV brightenings are the same event-type. We suggest that the term blinker be used as a generic term to describe these events. However, there appears to be little evidence that blinkers and explosive events are directly related. Furthermore, although a small percentage of blinkers and nanoflares/heating events appear to be related to one another, these events pose a number of important questions suggesting that either (i) blinkers and nanoflare/heating events are all created by the same mechanism, i.e. for some blinker events, the conditions are such that higher temperatures are found, or (ii) there are two types of event, including the ``traditional'' blinker which is effectively a transition region brightening driven by a density or filling factor enhancement, and a mini-flare-like event which reaches higher temperatures, presumably driven by reconnection. Title: Dynamics of Blinkers Authors: Bewsher, D.; Parnell, C. E.; Pike, C. D.; Harrison, R. A. Bibcode: 2003SoPh..215..217B Altcode: The relative Doppler and non-thermal velocities of quiet-Sun and active-region blinkers identified in O v with CDS are calculated. Relative velocities for the corresponding chromospheric plasma below are also determined using the He i line. O v blinkers and the chromosphere directly below, have a preference to be more red-shifted than the normal transition region and chromospheric plasma. The ranges of these enhanced velocities, however, are no larger than the typical spread of Doppler velocities in these regions. The anticipated ranges of Doppler velocities of blinkers are 10-15 km s−1 in the quiet Sun (10-20 km s−1 in active regions) for He i and 25-30 km s−1 in the quiet Sun (20-40 km s−1 in active regions) for O v. Blinkers and the chromosphere below also have preferentially larger non-thermal velocities than the typical background chromosphere and transition region. Again the increase in magnitude of these non-thermal velocities is no greater than the typical ranges of non-thermal velocities. The ranges of non-thermal velocities of blinkers in both the quiet Sun and active regions are estimated to be 15-25 km s−1 in He i and 30-45 km s−1 in O v. There are more blinkers with larger Doppler and non-thermal velocities than would be expected in the whole of the chromosphere and transition region. The recently suggested mechanisms for blinkers are revisited and discussed further in light of the new results. Title: Coronal dimming and the coronal mass ejection onset Authors: Harrison, R. A.; Bryans, P.; Simnett, G. M.; Lyons, M. Bibcode: 2003A&A...400.1071H Altcode: A set of five observations of extreme-ultraviolet (EUV) coronal dimming associated with coronal mass ejection (CME) activity is examined. Using spectroscopic data, plasma characteristics across a broad range of temperatures from 20 000 K to 2 million K are determined. The dimming events are found to coincide in time, and to coincide spatially, with the projected onset times and locations of the associated CMEs. The spectral data confirm that the dimming is due to mass-loss, and not temperature variations. The actual mass-loss calculated from the degree of dimming, using two different methods, shows that the extracted mass in each case, is of the same order as the mass of the associated CME. In some cases, the EUV observations are limited to relatively small regions under the CME events and it is expected that we do not witness the mass-loss associated with the entire event, for these. However, we believe that this analysis has provided a method for locating the source region of the trigger for a CME eruption, and that the dimming characteristics can be used to distinguish between onset processes of the CME. In particular, the gradual nature of the dimming process, which takes place over several hours, suggests that either the CME has a continuous driver rather than a sudden impulsive onset, or the low coronal response to a CME extends over a long period. Title: Design and tests for the heliospheric imager of the STEREO mission Authors: Defise, Jean-Marc; Halain, Jean-Philippe; Mazy, Emmanuel; Rochus, Pierre P.; Howard, Russell A.; Moses, J. Daniel; Socker, Dennis G.; Harrison, Richard A.; Simnett, George M. Bibcode: 2003SPIE.4853...12D Altcode: The Heliospheric Imager (HI) is part of the SECCHI suite of instruments on-board the two STEREO spacecrafts to be launched in 2005. The two HI instruments will provide stereographic image pairs of solar coronal plasma and coronal mass ejections (CME) over a wide field of view (~90°), ranging from 13 to 330 R0. These observations compliment the 15 R0 field of view of the solar corona obtained by the other SECCHI instruments (2 coronagraphs and an EUV imager). The key challenge of the instrument design is the rejection of the solar disk light, with total straylight attenuation of the order of 10-13 to 10-15. A multi-vane diffractive baffle system has been theoretically optimized to achieve the lower requirement (10-13 for HI-1) and is combined with a secondary baffling system to reach the 10-15 rejection performance in the second camera system (HI-2). This paper presents the last updates of the SECCHI/HI design concept, with the expected performance. A verification program is currently in progress. The on-going stray-light verification tests are discussed. A set of tests has been conducted in air, and under vacuum. The results are presented and compared with the expected theoretical data. Title: Preface Authors: Harrison, Richard A. Bibcode: 2003CIBu..158....3H Altcode: No abstract at ADS Title: Preface — The Columbia accident Authors: Harrison, Richard Bibcode: 2003CIBu..156....1H Altcode: No abstract at ADS Title: Soho observations relating to the association between flares and coronal mass ejections Authors: Harrison, R. A. Bibcode: 2003AdSpR..32.2425H Altcode: Campaigns to investigate the solar coronal mass ejection (CME) onset have been run using the Solar andHeliospheric Observatory (SOHO) since 1996. These have included coronagraph and extreme-ultraviolet (EUV) disc imaging, along with magnetic mapping of the photosphere, in concert with EUV and UV spectroscopic observations. These campaigns have included co-ordination with ground-based observatories, and with other spacecraft, especially Yohkoh and the Transition Region and Corona Explorer (TRACE). This multi-instrument, multi-spacecraft effort has provided many rewards, with some spectacular observations of countless eruptions. It has included the discovery of unexpected phenomena such as EUV waves and groundbreaking work on coronal dimming, and the development of sigmoidal shaped structures. Much has been learnt about the CME onset yet the most basic questions still remain. We have an unprecedented view of CME eruptions, yet we are still unable to identify clearly the onset process and we do not fully understand the CME-flare relationship. With all of the campaigns producing excellent multi-wavelength observations of CMEs, how far have we progressed in the understanding of the CME onset and, in particular, the CME-flare relationship? Can we identify lines of research using the SOHO data, which will provide the answers we seek — or do we need fundamentally different observation scenarios? It is the author's opinion that we actually have the observational tools required to understand much about the onset process and the CME/flare links, and the emphasis should be on understanding the limitations of our instrumentation and on removing any preconceived ideas from our interpretations. Title: Short-term solar effects Authors: Harrison, Richard A. Bibcode: 2003RSPTA.361...79H Altcode: No abstract at ADS 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: The STate of the ARt Telescope Educational Collaboration (STARTEC) Authors: Finley, D. G.; Alonso, J. L.; Altschuler, D.; Cianciolo, F.; Cuesta, L.; Harrison, R.; Hemenway, M. K.; Michaud, P.; Morison, I.; Preston, S.; Rijsdjk, C.; Teays, T.; West, R. M.; Wetzel, M. Bibcode: 2002AAS...201.1006F Altcode: 2002BAAS...34.1108F The State of the Art Telescope Educational Collaboration (STARTEC) was founded in February 2001 at a meeting in Cape Town, South Africa. The meeting was attended by educational representatives of some of the largest and most advanced astronomical facilities in the world. The attending representatives agreed that astronomy, a basic science with roots in every human culture, possesses an exceptional potential to attract public interest and elevate science literacy around the world. In addition, they agreed that large, state-of-the-art astronomical facilities, as public icons of science and technology, have a responsibility to assume a leading role in astronomy education and public outreach. Accordingly, STARTEC was formed to establish a forum for exchanging resources and expertise in education and public outreach. Goals of the collaboration include: inspiring the general public to appreciate and support astronomy; inspiring and preparing future generations of scientists, engineers and technicians; using the collective visibility of STARTEC institutions to improve science literacy through the news media and to improve public awareness of the threats of light pollution, radio interference and space debris to the world's astronomical environment; leveraging resources and fostering collaborations among STARTEC members for educational programs; and improving members' education and public outreach efforts as well as encouraging other institutions and other scientific disciplines to collaborate on educational and outreach programs. The current members of STARTEC are: Arecibo Observatory, the European Southern Observatory, Gemini Observatory, the Hubble Space Telescope, the Instituto de Astrofisica de Canarias and Gran Telescopio Canarias, Jodrell Bank Observatory/PPARC, McDonald Observatory and the Hobby-Eberly Telescope, the National Radio Astronomy Observatory, and the South African Astronomical Observatory/Southern Africa Large Telescope. Subsequent meetings of STARTEC were held at Arecibo Observatory in 2001 and at McDonald Observatory in 2002, and plans for cooperative educational efforts are underway. A STARTEC Web site will serve as a resource for those engaged in astronomical education and public outreach efforts. This work was supported by NSF Grant 0084618, "U.S.-South Africa Workshop: Educational Outreach for Observatories with State-of-the-Art Telescopes, Cape Town, South Africa, Feb. 2-6, 2001." The National Radio Astronomy Observatory is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc. Title: Coronal Dimming and the Relationship to Coronal Mass Ejections Authors: Harrison, R. A.; Howard, T. A.; Simnett, G. M. Bibcode: 2002AGUFMSH52A0485H Altcode: Around the onset time of coronal mass ejections (CME) it is frequently observed by the LASCO coronagraphs on SOHO that the mass content of the low corona is depleted. Spectral observations by the coronal diagnostic spectrometer (CDS) (also on SOHO) are able to confirm that this ``coronal dimming'' is in fact due to mass loss rather than temperature variations. An important question is whether the observed mass loss represents the actual mass ejected in the CME, or the mass required to replenish the coronal mass ejected in the CME. Clearly the timing of the mass loss observed in the low corona to the timing of the CME is critical in answering this question. We present recent results of dedicated campaigns using CDS to investigate this phenomenon; and we also examine the LASCO-C1 data from 1996--1998 (June) for additional information on the relationship between CME onsets and coronal dimming. Title: The International Heliophysical Year (IHY) Authors: Davila, J. M.; Harrison, R.; Poland, A.; Thompson, B.; Gopalswamy, N. Bibcode: 2002AGUFMSH21A0518D Altcode: In 1957 a program of international research, inspired by the International Polar Years of 1882-83 and 1932-33, was organized as the International Geophysical Year (IGY) to study global phenomena of the Earth and geospace. The IGY involved about 60,000 scientists from 66 nations, working at thousands of stations, from pole to pole to obtain simultaneous, global observations on Earth and in space. There had never been anything like it before. The fiftieth anniversary of the International Geophysical Year will occur in 2007. We propose to organize an international program of scientific collaboration for this time period called the International Heliophysical Year (IHY). Like it predecessors, the IHY will focus on fundamental global questions of Earth science. Title: Off-limb EUV line profiles and the search for wave activity in the low corona Authors: Harrison, R. A.; Hood, A. W.; Pike, C. D. Bibcode: 2002A&A...392..319H Altcode: Two extreme-ultraviolet (EUV) observations are used to examine the off-limb characteristics of emission line widths of the million K Mg X 625 Å line. To obtain sufficient statistical accuracy, the observations were made over long periods of time and a pixel summing technique is used. The observations are made above the western limb, for quiet corona. The most significant result is the discovery of emission line narrowing as a function of altitude and intensity at altitudes above 50 000 km. The results are compared to past observations, which suggest that emission line broadening, at lower altitudes, is due to the outward propagation of undamped Alfvén waves, in open field regions with decreasing density with altitude. The narrowing at higher altitudes, determined by the current study is interpreted as further evidence for coronal wave activity, but in closed field regions, and most likely the first evidence of the dissipation of Alfvén waves in the corona. An additional result of this work is the identification of a significant line broadening across a narrow region on the limb, which may be due to flows in low-lying loop systems. Title: Transition-Region Blinkers - II. Active-Region Properties Authors: Parnell, C. E.; Bewsher, D.; Harrison, R. A. Bibcode: 2002SoPh..206..249P Altcode: The distribution and general properties of events identified in an active region that have the same characteristics as quiet-Sun blinkers are discussed and named `active-region blinkers'. The events are identified using an automated scheme `BLinker Identification Program' (BLIP) which was designed for and tested on quiet-Sun blinkers. Like quiet-Sun blinkers, the active-region events are most easily identified in the 629 Å emission line from O v although evidence for them is also found in other extreme UV lines emitted from He i, O iii and O iv. Unlike quiet-Sun blinkers, however, they may also have coronal signatures in the lines Mg ix and Mg x. Their properties are very similar to those of quiet-Sun blinkers with mean lifetimes of 16-19 min, mean areas of 2.4-4.3×107 km2 and mean intensity enhancements factors of 1.8-3.3. Their global frequency of 7-28 s−1 is about 42%-700% higher than that for quiet-Sun blinkers. The blinkers discussed here are found above both active-region (plage) magnetic fields, as well as above the umbra and penumbra of a sunspot. Title: Transition Region Blinkers I. Quiet-Sun Properties Authors: Bewsher, D.; Parnell, C. E.; Harrison, R. A. Bibcode: 2002SoPh..206...21B Altcode: An automated method of identifying transition region blinkers is presented. The distribution and general properties of blinkers identified in the quiet Sun are discussed. The blinkers are seen most clearly in the O v (629 Å) transition region emission line, but they also have strong signatures in O iv (554 Å), and the chromospheric line, He i (584 Å). The strongest O v blinkers can also be identified in O iii (599 Å). No significant signatures are found for blinkers in the Mg ix (368 Å) and Mg x (624 Å) coronal lines. A few hundred O v blinkers are analyzed. Their global frequency is between 1 and 20 s−1 depending on how significant the peaks of the blinkers are. They have a typical area of 3×107 km2, a typical lifetime of 16 min and a typical intensity enhancement factor of 1.8. We find the ratios of the oxygen lines to be flat confirming the result that blinkers are not temperature events, but are density enhancements or due to increases in filling factor. Blinkers are found to occur preferentially over regions of enhanced chromospheric or transition region emission such as network boundaries, however, it is not so clear that they appear below the brightest coronal regions. A rough analysis of the magnetic fragments show that blinkers preferentially occur above regions where there are large or strong magnetic fragments with 75% occurring in regions where one polarity dominates. Title: International Solar Cycle Studies [ISCS] Working Group 2: solar magnetic field variability - from the lower atmosphere through the inner corona Authors: Harrison, Richard A.; Michels, Donald Bibcode: 2002AdSpR..29.1583H Altcode: This report is a summary of activities and plans relating to the International Solar Cycle Studies (ISCS) Working Group 2, which is concerned with solar magnetic field variability, from the lower atmosphere through the inner corona. Whilst the Working Group carries a rather general title, the activities are focusing on several well defined topics - in particular the onset of coronal mass ejection events. Recognising the large number of scientific meetings worldwide, the working style of this group is aimed at improving communication, information exchange and collaboration making use of existing meetings and with a minimum of red tape. The core of the activity is through the use of the World Wide Web and e-mail. In this way, this Working Group does not introduce extra effort, but provides a better focus for on-going projects. Title: A discussion on the practical aspects of running the IHY project Authors: Harrison, R. Bibcode: 2002cosp...34E1040H Altcode: 2002cosp.meetE1040H The International Heliophysical Year (IHY) is not simply a celebration of the 50th anniversary of the International Geophysical Year (IGY). It is designed to have a major scientific impact through the efficient co-ordination of many observations from space-based and ground-based instrumentation. The best approach may be through the development of Joint Observing Programmes (JOPs) in a style adopted so successfully for the co-ordination of the solar missions SOHO, Yohkoh and TRACE, but on a grander scale. The full IHY programme could consist of numerous JOPs each co-ordinated by an individual in pursuit of a particular scientific objective, using a set of well-defined instruments. The overall management of the programme would be performed by an international committee, ensuring efficient communication, exchange of information and overseeing the JOP activities. This 'grass roots' approach ensures that individual scientists can participate and gain from the IHY experience. The aim here is to discuss the approach and to give the community a chance to shape the IHY effort in the way it sees fit. This will be the first open discussion on IHY and will be used to lay the foundation for the practical application of the IHY concept. Title: SOHO observations relating to the association between flares and CMEs Authors: Harrison, R. Bibcode: 2002cosp...34E1034H Altcode: 2002cosp.meetE1034H Campaigns to investigate the onset of solar coronal mass ejection (CME) activity have been run using SOHO instrumentation since 1996. These have included coronagraph and extreme-ultraviolet (EUV) disc imaging, along with magnetic mapping of the photosphere, in concert with off-limb and near-limb EUV and UV spectroscopic observations. It has included coordination with other spacecraft, providing X-ray and high resolution EUV/UV imaging, as well as ground-based systems. This effort has provided many rewards, with spectacular observations of countless eruptions. It has included the discovery of unexpected phenomena such as coronal waves, the dimming of EUV coronal emission lines under CMEs and the observation of sigmoidal shaped structures associated with CMEs. Much has been learned about the CME onset process yet the most basic questions still remain. We have an unprecedented view of CME eruptions, yet we are still unable to identify clearly the onset process and we do not fully understand the relationship between flares and CMEs. With all of the campaigns producing excellent multi-wavelength observations of CMEs, how far have we progressed in the understanding of the CME onset and, in particular the relationship to the flare? Can we identify lines of research, using the SOHO data, which will provide the answers we seek. It is the author's opinion that we actually have the observational tools required to allow an understanding of the onset process and the CME/flare links, and the emphasis should be on understanding the limitations of our instrumentation and on removing any preconceived ideas from our interpretations. Title: The International Heliophysical Year Concept Authors: Davila, J.; Harrison, R.; Poland, A.; St-Cyr, O.; Thompson, B. Bibcode: 2002cosp...34E.529D Altcode: 2002cosp.meetE.529D In 1957 a program of international research, inspired by the International Polar Years of 1882-83 and 1932-33, was organized as the International Geophysical Year (IGY) to study global phenomena of the Earth and geospace. The IGY involved about 60,000 scientists from 66 nations, working at thousands of stations, from pole to pole to obtain simultaneous, global observations on Earth and in space. There had never been anything like it before. The fiftieth anniversary of the International Geophysical Year will occur in 2007. We propose to organize an international program of scientific collaboration for this time period called the International Heliophysical Year (IHY). Like its predecessors, the IHY will focus on fundamental global questions of Earth science. Title: Solar orbiter, a high-resolution mission to the sun and inner heliosphere Authors: Marsch, E.; Antonucci, E.; Bochsler, P.; Bougeret, J. -L.; Fleck, B.; Harrison, R.; Langevin, Y.; Marsden, R.; Pace, O.; Schwenn, R.; Vial, J. -C. Bibcode: 2002AdSpR..29.2027M Altcode: The scientific rationale of the Solar Orbiter is to provide, at high spatial (35 km pixel size) and temporal resolution, observations of the solar atmosphere and unexplored inner heliosphere. Novel observations will be made in the almost heliosynchronous segments of the orbits at heliocentric distances near 45 R⊙ and out of the ecliptic plane at the highest heliographic latitudes of 30° - 38°. The Solar Orbiter will achieve its wide-ranging aims with a suite of sophisticated instruments through an innovative design of the orbit. The first near-Sun interplanetary measurements together with concurrent remote observations of the Sun will permit us to determine and understand, through correlative studies, the characteristics of the solar wind and energetic particles in close linkage with the plasma and radiation conditions in their source regions on the Sun. Over extended periods the Solar Orbiter will deliver the first images of the polar regions and the side of the Sun invisible from the Earth. Title: Solar Orbiter: a high-resolution mission to the sun and inner heliosphere Authors: Fleck, Bernhard; Marsch, E.; Antonucci, Ester; Bochsler, Peter A.; Bougeret, J. L.; Harrison, R.; Marsden, R. P.; Coradini, M.; Pace, Oscar; Schwenn, Rainer; Vial, Jean-Claude Bibcode: 2001SPIE.4498....1F Altcode: The key mission objective of the Solar Orbiter is to study the Sun from close-up (45 solar radii, or 0.21 AU) in an orbit tuned to solar rotation in order to examine the solar surface and the space above from a co-rotating vantage point at high spatial resolution. Solar Orbiter will also provide images of the Sun's polar regions from heliographic latitudes as high as 38 degrees. The strawman payload encompasses two instrument packages: Solar remote-sensing instruments: EUV full-sun and high resolution imager, high-resolution EUV spectrometer, high-resolution and full-sun visible light telescope and magnetograph, EUV and visible-light coronagraphs, radiometers. Heliospheric instruments: solar wind analyzer, radio and plasma wave analyzer, magnetometer, energetic particle detectors, interplanetary dust detector, neutral particle detector, solar neutron detector. To reach its novel orbit, Solar Orbiter will make use of low-thrust solar electric propulsion (SEP) interleaved by Earth and Venus gravity assists. Solar Orbiter was selected by ESA's Science Programme Committee (SPC) in October 2000 as a Flexi-mission, to be implemented after the BepiColombo cornerstone mission to Mercury before 2013. This paper summarizes the science to be addressed with the Solar Orbiter, followed by brief descriptions of the strawman payload, the mission profile, and the spacecraft and ground segment designs. Title: EUV Sprays: Jet-like eruptive activity on the solar limb Authors: Harrison, R. A.; Bryans, P.; Bingham, R. Bibcode: 2001A&A...379..324H Altcode: Jet-like eruptive events have been detected in the extreme ultraviolet (EUV) observations from the Solar and Heliospheric Observatory (SOHO) spacecraft. Some jet-like events are shown and for one event, that of January 22 2000, we provide a detailed analysis of the EUV observations. The January 22 observation was part of an on-going campaign to observe the onset of coronal mass ejections (CMEs) using extreme ultraviolet spectroscopy. A high-temperature fan-like jet was first detected in emission lines from plasmas at one million K and over, and it appears to be the onset of a narrow mass ejection identified later in coronagraph data. This was followed by a dramatic jet or finger of cool (<=250 000 K), rotating plasma which extended vertically, high into the corona. It extended well beyond the field of view of the instrument and appears to relate to a small ejected cloud which is detected in subsequent coronagraph data. The spectroscopic characteristics are used to provide plasma diagnostic information for these two events, and this combined with images for a wide range of temperatures allows a thorough investigation of the processes leading to such eruptions. A simple accreting magnetic field model is used to descibe the basic features of the jet activity. Title: Solar Orbiter EUV/UV wavelength selection and instrumentation - report of Payload Splinter Group 4 Authors: Harrison, R. A.; Vial, J. -C. Bibcode: 2001ESASP.493..151H Altcode: 2001sefs.work..151H We present here a summary of the discussions concerning the extreme ultraviolet (EUV) and ultraviolet (UV) wavelength selection and instrumentation for Solar Orbiter, held at the Tenerife meeting. These issues were assigned to Payload Splinter Group 4 and to the Wavelength Selection Working Group. Concerning the wavelength selection, a number of critical wavelength ranges were highlighted and discussed. Great emphasis was placed on good atmospheric coverage, from the chromosphere to the hottest coronal lines. A number of wavelength ranges were presented but the wide temperature range demands the inclusion of wavelengths longer than 912 Å as well as prime coronal lines in much shorter wavelength ranges, such as 170-250 Å. Regarding the instrumentation, the group agreed that Solar Orbiter should carry both imaging and spectroscopic capability in the EUV/UV and the two strawman instruments were presented and discussed. A number of alternatives were considered as were developments in technology, which could be of use for these instruments. Title: Solar Orbiter, a high-resolution mission to the Sun and inner heliosphere Authors: Marsch, E.; Harrison, R.; Pace, O.; Antonucci, E.; Bochsler, P.; Bougeret, J. -L.; Fleck, B.; Langevin, Y.; Marsden, R.; Schwenn, R.; Vial, J. -C. Bibcode: 2001ESASP.493D..11M Altcode: 2001sefs.workD..11M Solar Orbiter will provide, at very high spatial (35 km pixel size) and temporal resolution, novel observations of the solar atmosphere and unexplored inner heliosphere. It will achieve its wide-ranging scientific aims with a suite of sophisticated instruments through an innovative orbit design. Unprecedented observations will be made in the heliosynchronous segments of the orbits at heliocentric distances near 45 Rsolar and out of the ecliptic plane at the highest heliographic latitudes of 30° - 38°. The first near-Sun interplanetary measurements together with concurrent remote-sensing observations of the Sun and its corona will permit us to determine and understand, through correlative studies, the characteristics of the solar wind and energetic particles in close linkage with the plasma and radiation conditions in the source regions on the Sun. Solar Orbiter will deliver the first images of the polar regions and the far side of the Sun invisible from the Earth. Title: Joint EUV/Radio Observations of a Solar Filament Authors: Chiuderi Drago, F.; Alissandrakis, C. E.; Bastian, T.; Bocchialini, K.; Harrison, R. A. Bibcode: 2001SoPh..199..115C Altcode: In this paper we compare simultaneous extreme ultraviolet (EUV) line intensity and microwave observations of a filament on the disk. The EUV line intensities were observed by the CDS and SUMER instruments on board SOHO and the radio data by the Very Large Array and the Nobeyama radioheliograph. The main results of this study are the following: (1) The Lyman continuum absorption is responsible for the lower intensity observed above the filament in the EUV lines formed in the transition region (TR) at short wavelengths. In the TR lines at long wavelengths the filament is not visible. This indicates that the proper emission of the TR at the filament top is negligible. (2) The lower intensity of coronal lines and at radio wave lengths is due to the lack of coronal emission: the radio data supply the height of the prominence, while EUV coronal lines supply the missing hot matter emission measure (EM). (3) Our observations support a prominence model of cool threads embedded in the hot coronal plasma, with a sheath-like TR around them. From the missing EM we deduce the TR thickness and from the neutral hydrogen column density, derived from the Lyman continuum and He i absorption, we estimate the hydrogen density in the cool threads. Title: Transition Region Blinkers Authors: Parnell, C. E.; Bewsher, D.; Harrison, R. A.; Hood, A. W. Bibcode: 2001IAUS..203..359P Altcode: Blinkers are small bright emission events observed best in the O V transition region line that occur above the supergranular network. They were first observed using SoHO/CDS data and were identified manually by Harrison (1997). They are believed to be density enhancements, but how they are created and what their properties are is not well known. We have developed the first program to automatically identify blinkers and their characteristics. The evolution of the magnetic field observed by SoHO/MDI below these blinkers has then be analysed to determine what magnetic field configuration is required for a blinker to occur. Also, the coronal emission above has been investigated using SoHO/CDS and TRACE data to determine the relation between blinkers, x-ray bright points and nanoflares. All three of these events are known to occur at the network, but as yet the relation between them is not understood. Putting together the results from these multi-wave length studies we have been able to determine a model for how blinkers occur and what their effect is on the transition region around and the corona above. Title: Solar Orbiter, a High-Resolution Mission to the Sun and Inner Heliosphere Authors: Marsch, E.; Antonucci, E.; Bochsler, P.; Bougeret, J. -L.; Fleck, B.; Harrison, R.; Marsden, R.; Schwenn, R.; Vial, J. -C. Bibcode: 2001IAUS..203..565M Altcode: The scientific rationale of the Solar Orbiter (SO) is to provide, at high spatial and temporal resolution, observations of the solar atmosphere and unexplored inner heliosphere. The most interesting and novel observations will be made in the almost heliosynchronous segments of the orbits at heliocentric distances near 45 Rodot and out-of-ecliptic at the highest heliographic latitudes of 38 degrees. The SO will achieve its many and varied aims with a suite of small and innovative instruments through a clever choice of orbits. The first near-Sun interplanetary measurements together with concurrent remote observations of the Sun will permit us to determine and understand, through correlative studies, the characteristics of the solar wind and energetic particles in close linkage with the plasma and radiation conditions in their source regions on the Sun. The SO will, during the high-latitude orbital passes, provide the first observations of the Sun's polar regions as seen from outside the ecliptic and also measure the magnetic field at the poles. Title: On the Detection of Solar Coronal High-Velocity Fields Using the XUV Doppler Telescope Authors: Kobayashi, Ken; Hara, Hirohisa; Kano, Ryohei; Nagata, Shin'ichi; Sakao, Taro; Shimizu, Toshifumi; Tsuneta, Saku; Yoshida, Tsuyoshi; Harrison, Richard Bibcode: 2000PASJ...52.1165K Altcode: The XUV Doppler Telescope (XDT) is a sounding rocket experiment designed to detect flows in the solar corona using filter ratios. The XDT, successfully launched on 1998 January 31, is a normal incidence telescope composed of narrow-bandpass multilayer mirrors and capable of obtaining images 2 Å\ above and 2 Å\ below the Fe XIV 211 Å\ (T = 1.7 MK) emission line. It has the potential to make a velocity map of the entire solar disk with just a few minutes of observation. The image ratio maps show features that translate to Doppler shifts of 200 km s-1 or more, including several `redshift' features located near footpoints of coronal loops. However, no corresponding velocity features were seen by the Solar and Heliospheric Observatory (SOHO) Coronal Diagnostic Spectrometer (CDS) in the Mg IX 368 Å (T = 1 MK) line, suggesting that the features are not caused by Doppler shift. Instead, the features seem to be related to contamination of lower temperature (T < 1 MK) emission lines and the nearby density-sensitive Fe XIII lines. We conclude that while no flows were positively identified by the XDT, this observing technique is capable of detecting flows of 1000 km s^{-1} independently, and 200 km s^{-1}$ when combined with simultaneous plasma diagnostic observation. Title: Solar Coronal Mass Ejection: Observations Authors: Harrison, R. Bibcode: 2000eaa..bookE2029H Altcode: The Sun ejects matter into space. There appear to be two basic ejection classes, the first leading to the SOLAR WIND outflow, and the second leading to the occasional ejection of huge, discrete clouds known as coronal mass ejections (CMEs). First identified in the early 1970s, a typical CME can carry 1 000 000 000 t of plasma into space as part of the Sun's atmosphere erupts. The CME source regio... Title: Long-duration cosmic ray modulation from a Sun-Earth L1 orbit Authors: Pike, C. D.; Harrison, R. A. Bibcode: 2000A&A...362L..21P Altcode: We analyse cosmic ray hits impacting the detector system of the Coronal Diagnostic Spectrometer aboard the Solar and Heliospheric Observatory spacecraft. These observations allow us to study the modulation of cosmic rays over a 4 year period (1996-2000) running from solar minimum to maximum, from a Sun-Earth L1 Lagrangian orbit. The modulation, at the 45-50% level is consistent with cosmic rays of energy 1 GeV. Title: A spectroscopic study of coronal dimming associated with a coronal mass ejection Authors: Harrison, R. A.; Lyons, M. Bibcode: 2000A&A...358.1097H Altcode: Extreme ultraviolet spectroscopic observations of one coronal mass ejection event are used to examine the onset phase of the eruption. We find significant dimming of million K plasmas in the low corona under the ascending CME, the activation of an adjacent prominence and 2 million K `hot spots' which may be associated with the CME footpoints. In particular, we show that the dimming is due to a density decrease from million K plasma loss. We compare the mass loss with the CME mass. The observations suggest that the interaction of adjacent coronal loops plays an important role in CME activity and may allow us to pinpoint the source of the CME material. Title: A study of opacity in SOHO-SUMER and SOHO-CDS spectral observations. I. Opacity deduction at the limb Authors: Brooks, D. H.; Fischbacher, G. A.; Fludra, A.; Harrison, R. A.; Innes, D. E.; Landi, E.; Landini, M.; Lang, J.; Lanzafame, A. C.; Loch, S. D.; McWhirter, R. W. P.; Summers, H. P. Bibcode: 2000A&A...357..697B Altcode: A study is presented of the optical thickness of spectral lines of carbon, nitrogen and oxygen ions in the quiet sun. The observations consist of cross limb scans by the SUMER and CDS spectrometers on the SOHO spacecraft. A maximum likelihood spectral line fitting code has been adapted to analyse the multiplet profiles and to provide an assessment of errors in the count rates, especially of close lying components. Branching multiplet component ratios are presented as a function of position across the limb and contrasted with theoretical ratios in the optically thin case. The emergent fluxes are analysed in an escape probability model to deduce the optical thicknesses in the various spectral lines. Different specifications of the escape probability are examined. These are used to compare the observations with a geometric model of the emitting layer thickness across the limb and the thinning of the emitting layer above the limb. Classification of the deviations of quiet sun spectral line intensities from the optically thin case is given to assist in the critical selection of lines for differential emission measure analysis. This is linked to a general purpose code for the calculation of the influence of the line radiation fields on the local excited state population structure of the selected ions so that the fluxes in any spectral lines can be predicted. The Atomic Data and Analysis Structure (ADAS) was used for the atomic calculations and data of the paper. Title: Solar Orbiter --- A High Resolution Mission to the Sun and Inner Heliosphere Authors: Fleck, B.; Marsch, E.; Schwenn, R.; Antonucci, E.; Bochsler, P.; Bougeret, J. -L.; Harrison, R. A.; Marsden, R.; Vial, J. -C. Bibcode: 2000SPD....31.0296F Altcode: 2000BAAS...32..828F The scientific rationale of the Solar Orbiter (SO) is to provide, at high spatial and temporal resolution, observations of the solar atmosphere and unexplored inner heliosphere. The most interesting and novel observations will be made in the almost heliosynchronous segments of the orbits at heliocentric distances near 45 Rsun and out-of-ecliptic at heliographic latitudes of up to 38o. By going to 45 Rsun the SO will allow remote sensing of the solar atmosphere with unprecedented spatial resolution, and the almost heliosynchronous orbit segments will permit us to disentangle spatial and temporal variations in the solar wind in close linkage with the plasma and radiation conditions in the source regions of the Sun. The strawman payload encompasses two instrument packages: Heliospheric Instruments --- high-res visible light telescope and magnetograph (<40 km), high-res X-ray/EUV imager (<30 km), high-res EUV spectrometer (<100 km), EUV and visible-light coronagraphs, solar neutron and γ -ray detectors, radiometers. Heliospheric Instruments --- solar wind analyzer, magnetometer, energetic particle detectors, IP dust detector, plasma wave analyser, radio experiment, neutral particle detector. Using solar electric propulsion (SEP) in conjunction with multiple planet swing-by manoeuvres, it will take SO two years to reach a perihelion of 45 Rsun at an orbital period of 149 days, with an inclination ranging from 6.7o to 23.4o w.r.t. the ecliptic. During an extended mission phase of about 2 years the inclination will increase to 31.7o, leading to a maximum heliographic latitude of 38.3o. The SO was one of the about 40 responses to the Call for Proposals for the next two "flexi-missions" (F2 and F3) within ESA's Scientific Programme. At its meeting on 1 March 2000, ESA's Space Science Advisory Committee recommended the Solar Orbiter among 5 other proposals for an assessment study. Launch is expected by the end of the decade. Title: EUV brightness variations in the quiet Sun Authors: Brković, A.; Rüedi, I.; Solanki, S. K.; Fludra, A.; Harrison, R. A.; Huber, M. C. E.; Stenflo, J. O.; Stucki, K. Bibcode: 2000A&A...353.1083B Altcode: The Coronal Diagnostic Spectrometer (CDS) onboard the SOHO satellite has been used to obtain movies of quiet Sun regions at disc centre. These movies were used to study brightness variations of solar features at three different temperatures sampled simultaneously in the chromospheric He I 584.3 Ä (2 * 104 K), the transition region O V 629.7 Ä (2.5 * 105 K) and coronal Mg IX 368.1 Ä (106 K) lines. In all parts of the quiet Sun, from darkest intranetwork to brightest network, we find significant variability in the He I and O V line, while the variability in the Mg IX line is more marginal. The relative variability, defined by rms of intensity normalised to the local intensity, is independent of brightness and strongest in the transition region line. Thus the relative variability is the same in the network and the intranetwork. More than half of the points on the solar surface show a relative variability, determined over a period of 4 hours, greater than 15.5% for the O V line, but only 5% of the points exhibit a variability above 25%. Most of the variability appears to take place on time-scales between 5 and 80 minutes for the He I and O V lines. Clear signs of ``high variability'' events are found. For these events the variability as a function of time seen in the different lines shows a good correlation. The correlation is higher for more variable events. These events coincide with the (time averaged) brightest points on the solar surface, i.e. they occur in the network. The spatial positions of the most variable points are identical in all the lines. Title: Emerging Flux and Coronal Heating: Small-Scale Transient Events in the Low Solar Atmosphere Authors: Harrison, R. A. Bibcode: 1999ESASP.448..531H Altcode: 1999mfsp.conf..531H; 1999ESPM....9..531H No abstract at ADS Title: A study of extreme ultraviolet blinker activity Authors: Harrison, R. A.; Lang, J.; Brooks, D. H.; Innes, D. E. Bibcode: 1999A&A...351.1115H Altcode: In a previous paper (Harrison, 1997a), we reported on the existence of extreme ultraviolet (EUV) flashes, known as blinkers, which were identified in the quiet Sun network using the CDS instrument on board the Solar and Heliospheric Observatory. Since then a number of dedicated observations have been made and we report here on an analysis of 97 blinker events. We identify blinker spectral, temporal and spatial characteristics, their distribution, frequency and general properties, across a broad range of temperatures, from 20,000 K to 1,200,000 K. The most significant brightenings were found in the transition region temperature lines of O III, O IV and O V, with modest or no detectable increases at higher or lower temperatures. A typical blinker event has a duration of order 1000 s, though the detection of short-duration blinkers may well be limited by the observation methods. However, a long tail of longer-duration blinkers puts the average blinker duration at almost 2400 s. Comparisons to plasma cooling times establish firmly that there is a continuous energy input throughout the blinker event. The projected blinker onset rate for the entire solar surface is 1.24 s-1 i.e. 3,000 blinker events may be in progress at any point in time. An examination of the line ratios shows a remarkable feature. Ratios of lines from O III, O IV and O V show no significant change throughout the blinker event and this indicates that the blinkers are predominantly caused by inceases in density or filling factor. The intensity signatures of the blinkers are modelled using a basic time dependent code and this confirms that the lack of a change in the oxygen line ratios is consistent with a density or filling factor increase in a plasma cooling from a temperature above 5 x 105 K. We estimate the thermal energy content of an average blinker at 2 x 1025 erg and consider this figure and the total blinker rate in the light of the energy required for coronal heating. The results are used to compare blinker activity to reported micro-flare, network flare and explosive event activity, and to discuss their potential role in coronal heating and solar wind acceleration processes. Finally, a blinker model is presented which consists of the merging of a closed magnetic system with pre-existing open field lines in the network. Title: Wavelet Analysis Of Active Region Oscillations Authors: Ireland, J.; Walsh, R. W.; Priest, E. R.; Harrison, R. A. Bibcode: 1999ESASP.446..363I Altcode: 1999soho....8..363I The wavelet transform is applied to the analysis of active region oscillations. The localised (in time) nature of the wavelet transform allows us to study both the duration of any statistically significant oscillations as well as their period. Time series arising from SOHO (Solar and Heliospheric Observatory) CDS-NIS (Coronal Diagnostic Spectrometer Normal Incidence Spectrometer) active region observations on 14th-15th November 1996 are used to demonstrate the applicability of wavelet methods. High cadence (approximately 14 seconds) observations were made in He I 584.33 Angstroms (log T = 4.3, T being the electron temperature), O V 629.73 Angstroms(log T = 5.3), Mg IX 368.06 Angstroms (log T = 6.0), Fe XVI 360.76 Angstroms (log T = 6.4) provide detailed intensity information on the active region over a wide range of temperatures. The distribution of statistically significant periods found varies from line to line, as does their duration. Title: The quiet Sun extreme ultraviolet spectrum observed in normal incidence by the SOHO coronal diagnostic spectrometer Authors: Brooks, D. H.; Fischbacher, G. A.; Fludra, A.; Harrison, R. A.; Innes, D. E.; Landi, E.; Landini, M.; Lang, J.; Lanzafame, A. C.; Loch, S. D.; McWhirter, R. W. P.; Summers, H. P.; Thompson, W. T. Bibcode: 1999A&A...347..277B Altcode: The extreme ultraviolet quiet Sun spectrum, observed at normal incidence by the Coronal Diagnostic Spectrometer on the SOHO spacecraft, is presented. The spectrum covers the wavelength ranges 308-381 Ä and 513-633 Ä and is based on data recorded at various positions on the solar disk between October 1996 and February 1997. Datasets at twelve of these `positions' were judged to be free from active regions and data faults and selected for detailed study. A constrained maximum likelihood spectral line fitting code was used to analyse the spectral features. In all over 200 spectrum lines have been measured and about 50% identified. The line identification process consisted of a number of steps. Firstly assignment of well known lines was made and used to obtain the primary wavelength calibration. Variations of wavelengths with position were used to assess the precision of calibration achievable. Then, an analysis method first used in studies with the CHASE experiment, was applied to the new observations. The behaviour of the intensities of lines from like ions over the twelve positions, called `position patterns', were used to distinguish probable emitters of weaker lines and extend the identifications. Spectral line widths and expected multiplet intensities were examined to identify lines and probable blends. The product of the study is a table which includes all clearly observed emission lines, their measured wavelengths, widths and count rates. Adopted laboratory wavelengths, ion and transition designations are also presented for identified lines. The table has an estimate of the uncertainty of the count rates based on a statistical analysis of the variability of each line. A marked spectrum is also provided. Title: A wavelet analysis of active region oscillations Authors: Ireland, J.; Walsh, R. W.; Harrison, R. A.; Priest, E. R. Bibcode: 1999A&A...347..355I Altcode: The wavelet transform is applied to the analysis of active region oscillations. The localised (in time) nature of the wavelet transform allows us to study both the duration of any statistically significant oscillations as well as their period. Time series arising from SOHO (Solar and Heliospheric Observatory) CDS-NIS (Coronal Diagnostic Spectrometer Normal Incidence Spectrometer) active region observations on 14th-15th November 1996 are used to demonstrate the applicability of wavelet methods. High cadence (approximately 14 seconds) observations were made in {He I} 584.33 Ä (log Te=4.3), {O V} 629.73 Ä (log Te=5.3), {Mg IX} 368.06 Ä (log Te=6.0), {Fe XVI} 360.76 Ä (log Te=6.4) provide detailed intensity information on the active region over a wide range of temperatures. The distribution of statistically significant periods found varies from line to line, as does their duration. Title: Multi-wavelength observations of the onset phase of a coronal mass ejection Authors: Innes, D. E.; Inhester, B.; Srivastava, N.; Brekke, P.; Harrison, R. A.; Matthews, S. A.; Noëns, J. C.; Schmieder, B.; Thompson, B. J. Bibcode: 1999SoPh..186..337I Altcode: The structure and dynamics of the initial phases of a coronal mass ejection (CME) seen in soft X-ray, extreme ultraviolet and optical emission are described. The event occurred on the SW limb of the Sun in active region AR 8026 on 9 April 1997. Just prior to the CME there was a class C1.5 flare. Images taken with the Extreme Ultraviolet Imaging Telescope (EIT) reveal the emergence of a candle-flame shaped extreme ultraviolet (EUV) cavity at the time of the flare. Yohkoh images, taken about 15 min later, show that this cavity is filled with hot X-ray emitting gas. It is most likely that this is the site of the flare. Almost simultaneous to the flare, an Hα surge or small filament eruption occurs about 50 arc sec northwards along the limb from the EUV cavity. At both the site of the core of the hot, EUV cavity and the filament ejection are X-ray jets. These jets seem to be connected by hot loops near their bases. Both jets disappear within a few minutes of one another. Title: Future Directions in Solar EUV/UV Spectroscopy Authors: Harrison, R. A. Bibcode: 1999AAS...194.6505H Altcode: 1999BAAS...31..927H Studies of the extreme ultraviolet (EUV) and ultraviolet (UV) spectrum of the Sun provide a unique and powerful means to investigate plasma properties, such as density, temperature, abundance and flow speeds throughout the low solar atmosphere, from chromsphere to corona. In particular, with the SOHO mission, recent EUV/UV spectroscopic studies have paved the way for significant advances in numerous areas of solar physics research, such as active region structure and evolution, quiet Sun transient processes, mass ejection onset, and so on... and the wealth of data will guarantee that we will be reaping the rewards for some time to come. However, spectroscopy demands relatively high mass, high telemetry instrumentation, and the products are not readily understood by the non-specialist. Thus, with the new breed of lighter missions and a greater need to enhance public awareness, what is the future for solar EUV/UV spectroscopy? The NASA STEREO mission due for launch in 2004 is not expected to carry a spectrometer. The Japanese Solar-B mission will be carrying an EUV spectrometer. The need for such instruments for the possible ESA Solar Orbiter, the NASA Solar Probe and other future missions must be addressed. SOHO comes from mid-1980's technology so we can readily enhance our current performances with the use of multilayers, improved CCD technology, multi-line-of-sight observations etc... So, as well as advertising the success of solar spectroscopy in recent years, an outline of possible directions willl be given which will underline the strong case for including such experiments in future solar missions. Title: A new view of our star: observations from SOHO. Authors: Harrison, R. A. Bibcode: 1999PhyEd..34..112H Altcode: The ESA/NASA Solar and Heliospheric Observatory (SOHO) spacecraft is revolutionizing our view of our star, the Sun. Its 12 instrument payload allows one to delve into the body of the Sun itself, to observe the mysterious solar atmosphere and to investigate the influence of the Sun on interplanetary space. The mission has come up with a string of new discoveries and has shown that in many ways the Sun is not quite as we expected it to be. The authors glance at our closest star and review the results, in particular, from a British-led instrument. Title: New views of our nearest star. Authors: Harrison, R. Bibcode: 1999AsNow..13R..52H Altcode: 1999AstNw..13R..52H "Focus: Basking in the Sun". A large range of instruments on board SOHO have produced spectacular results. Title: Brightness Variations in the Solar Atmosphere as Seen by SOHO Authors: Brkovic, A.; Rüedi, I.; Solanki, S. K.; Huber, M. C. E.; Stenflo, J. O.; Stucki, K.; Harrison, R.; Fludra, A. Bibcode: 1999ASSL..239..231B Altcode: 1999msa..proc..231B We present preliminary results of a statistical analysis of the brightness variations of solar features at different levels in the solar atmosphere. We observed quiet Sun regions at disc centre using the Coronal Diagnostic Spectrometer (CDS) onboard the Solar and Heliospheric Observatory (SOHO). We find significant variability at all time scales in all parts of the quiet Sun, from darkest intranetwork to brightest network. Such variations are observed simultaneously in the chromospheric He I 584.33 Angstroms (2 \cdot 10^4 K) line, the transition region O V 629.74 Angstroms (2.5 \cdot 10^5 K) and coronal Mg IX 368.06 Angstroms (10^6 K) line. The relative variability is independent of brightness and most of the variability appears to take place on time scales longer than 5 minutes for all 3 spectral lines. No significant differences are observed between the different data sets. Title: Our New View of the Sun - Results from the Solar and Heliospheric Observatory Authors: Harrison, R. A. Bibcode: 1999JBIS...52..434H Altcode: Over the last three years the Solar and Heliospheric Observatory (SOHO) has been revolutionising our view of our star, the Sun. A review of some of the new results from SOHO is given here, with a particular emphasis on the solar atmosphere - the source of the so-called `space weather'. The results include a rather unexpected feature of the nature of so-called active regions on the Sun, the discovery of new solar phenomena, such as solar tornadoes and jets, a new view of the nature of the quiet Sun, and a new insight into the way the Sun ejects vast clouds known as coronal mass ejections into space. Title: SOHO Observations of the Connection Between Line Profile Parameters in Active and Quiet Regions and the Net Red Shift in EUV Emission Lines Authors: Brynildsen, N.; Brekke, P.; Fredvik, T.; Haugan, S. V. H.; Kjeldseth-Moe, O.; Maltby, P.; Harrison, R. A.; Wilhelm, K. Bibcode: 1998SoPh..181...23B Altcode: We present high spatial and spectral resolution observations of one active and one quiet-Sun region, obtained with CDS and SUMER on SOHO. The connections between the line profile parameters are studied and a systematic wavelength shift towards the red with increasing peak line intensity (line broadening) is detected. The large scatter in the data calls for another approach. We apply conditional probability analysis to a series of EUV emission lines and find significant correlations between line profile parameters. For a given interval in wavelength shift we find that: (1) line profiles with large intensities (line widths) and red shifts above the average constitute an increasing fraction of the profiles as the relative wavelength shift increases, (2) line profiles with large intensities (line widths) and blue shifts compared to the average, on the other hand, constitute a decreasing fraction of the profiles as the relative wavelength shift increases. These results extend the findings of an earlier quiet-Sun study from one to several emission lines and expand the validity to include the active region. Interestingly, the active region observations show correlations between peak line intensity and wavelength shift in the coronal lines. Title: First Results from the TRACE Mission Authors: Title, A.; Tarbell, T.; Schrijver, C.; Wolfson, J.; Shine, R.; Hurlburt, N.; Golub, L.; Deluca, E.; Bookbinder, J.; Handy, B.; Acton, L.; Harrison, R.; Delaboudinere, J. -P. Bibcode: 1998AAS...192.1507T Altcode: 1998BAAS...30..841T The TRACE spacecraft was launched on 1 April and all systems are functioning as designed. The initial outgassing period will conclude on 20 April and the science program will then begin. TRACE is a UV-EUV imager with one arc second spatial resolution and is capable of taking images with a cadence as high as two seconds. We will present images and image sequences. We hope to present initial comparisons of magnetic evolution and transition region and coronal brightenings. Title: EUV Spectroscopy of the Sunspot Region NOAA 7981 Using SOHO - II. Velocities and Line Profiles Authors: Brynildsen, N.; Brekke, P.; Fredvik, T.; Haugan, S. V. H.; Kjeldseth-Moe, O.; Maltby, P.; Harrison, R. A.; Pike, C. D.; Rimmele, T.; Thompson, W. T.; Wilhelm, K. Bibcode: 1998SoPh..179..279B Altcode: We have studied the dynamics in the sunspot transition region between the chromosphere and the corona and investigated the extension of the flow field into the corona. Based on EUV spectra of a medium size sunspot and its surroundings, NOAA 7981, observed with CDS and SUMER on SOHO, we derive line-of-sight velocities and study the line profiles for a series of emission lines. Title: EUV Spectroscopy of the Sunspot Region NOAA 7981 Using SOHO - I. Line Emission and Time Dependence Authors: Brynildsen, N.; Brekke, P.; Fredvik, T.; Haugan, S. V. H.; Kjeldseth-Moe, O.; Maltby, P.; Harrison, R. A.; Pike, C. D.; Rimmele, T.; Thompson, W. T.; Wilhelm, K. Bibcode: 1998SoPh..179...43B Altcode: EUV spectra of a medium-size sunspot and its surroundings, NOAA 7981, were obtained on 2 August 1996 with the Coronal Diagnostic Spectrometer (CDS) and the Solar Ultraviolet Measurements of Emitted Radiation (SUMER) on the Solar and Heliospheric Observatory (SOHO). The spectral lines formed in the transition region and corona show considerable structure and large deviations from a uniform spatial distribution over the active region. Enhanced EUV emissions in transition region lines are concentrated in small regions outside the umbra of the sunspot throughout most of the observing sequence. Only during a short, active period do we find an enhanced line emission that reaches into the umbra. Preliminary values for the umbral intensity are given. Title: Coordinated Observations with SOHO, YOHKOH and VLA Authors: Aschwanden, Markus J.; Bastian, Tim S.; Nitta, Nariaki; Newmark, Jeff; Thompson, Barbara J.; Harrison, Richard A. Bibcode: 1998ASPC..155..311A Altcode: 1998sasp.conf..311A No abstract at ADS Title: 3-Dimensional Models of Active Region Loops Authors: Aschwanden, M. J.; Neupert, W. M.; Newmark, J.; Thompson, B. J.; Brosius, J. W.; Holman, G. D.; Harrison, R. A.; Bastian, T. S.; Nitta, N.; Hudson, H. S.; Zucker, A. Bibcode: 1998ASPC..155..145A Altcode: 1998sasp.conf..145A No abstract at ADS Title: Three Dimensional EUV Imaging of Sunspot Regions Observed with SOHO Authors: Brynildsen, N.; Brekke, P.; Haugan, S. V. H.; Kjeldseth-Moe, O.; Maltby, P.; Harrison, R. A.; Rimmele, T.; Wilhelm, K. Bibcode: 1998ASPC..155..171B Altcode: 1998sasp.conf..171B No abstract at ADS Title: EUV and Microwave Observations of a Filament Authors: Chiuderi-Drago, F.; Bocchialini, K.; Lamartinie, S.; Vial, J. -C.; Bastian, T.; Alissandrakis, C. E.; Harrison, R.; Delaboudiniere, J. -P.; Lemaire, P. Bibcode: 1998ASPC..150...55C Altcode: 1998IAUCo.167...55C; 1998npsp.conf...55C No abstract at ADS Title: Quiescent filament diagnostic. Authors: Lamartinie, S.; Bocchialini, K.; Vial, J. -C.; Chiuderi-Drago, F.; Harrison, R.; Alissandrakis, C. E. Bibcode: 1998joso.proc..139L Altcode: UV observations of a quiescent filament were performed on July 28, 1996 by SUMER and CDS, two spectrometers onboard SOHO. Title: EUV Spectral Variability and Non-Equilibrium Ionisation in the 'Quiet' Sun Authors: Brooks, D. H.; Summers, H. P.; Harrison, R. A.; Lang, J.; Lanzafame, A. C. Bibcode: 1998Ap&SS.261...91B Altcode: 1999Ap&SS.261...91B Recent spectroscopic observations by the Solar and Heliospheric Observatory (SOHO) have revealed the dynamic nature of even the 'quiet' Sun. Spectral variability data clearly show that dynamics in the solar upper atmosphere take place on timescales shorter than those of ionisation relaxation. Accuracy in the interpretation of diagnostic spectral data can only be maintained through detailed quantitative modelling of the relevant atomic physics. In particular, dynamical plasma models of the solar plasma require matching dynamic atomic models to underpin conclusions drawn from the spectral reduction. The inclusion of important effects such as finite plasma electron density and the influence of metastable levels is essential to reduce the uncertainties associated with equilibrium assumptions. Title: Preface Authors: Harrison, Richard Bibcode: 1998CIBu..142....2H Altcode: No abstract at ADS Title: European Plans for the Solar/Heliospheric Stereo Mission Authors: Bothmer, V.; Bougeret, J. -L.; Cargill, P.; Davila, J.; Delaboudiniere, J. -P.; Harrison, R.; Koutchmy, S.; Liewer, P.; Maltby, P.; Rust, D.; Schwenn, R. Bibcode: 1998ESASP.417..145B Altcode: 1998cesh.conf..145B No abstract at ADS Title: The Coronal Diagnostic Spectrometer on SOHO Authors: Phillips, K. J. H.; Harrison, R. A. Bibcode: 1998ASSL..229..227P Altcode: 1998opaf.conf..227P No abstract at ADS Title: Scientific Achievements of SOHO: The Solar Atmosphere Authors: Harrison, R. A. Bibcode: 1998ESASP.417...19H Altcode: 1998cesh.conf...19H No abstract at ADS Title: Overview of Results from IACG Campaign 3: CME Onsets Authors: Harrison, R. A. Bibcode: 1997ESASP.415..121H Altcode: 1997cpsh.conf..121H No abstract at ADS Title: Active Regions Observed in Extreme Ultraviolet Light by the Coronal Diagnostic Spectrometer on SOHO Authors: Fludra, A.; Brekke, P.; Harrison, R. A.; Mason, H. E.; Pike, C. D.; Thompson, W. T.; Young, P. R. Bibcode: 1997SoPh..175..487F Altcode: We present observations of five active regions made by the Coronal Diagnostic Spectrometer (CDS) on the Solar and Heliospheric Observatory (SOHO). CDS observes the Sun in the extreme ultraviolet range 150-780 Å. Examples of active region loops seen in spectral lines emitted at various temperatures are shown. Several classes of loops are identified: those that are seen in all temperatures up to 2 x 106 K; loops seen at 106 K but not reaching 1.6 x 106 K; those at temperatures 2- 4 x 10-5 K and occasionally at 6 x 10-5 K but not reaching 106 K. An increasing loop size with temperature and the relationship between the cool and hot structures is discussed. CDS observations reveal the existence of loops and other unresolved structures in active regions, at temperatures between 1.5- 4 x 10-5 K, which do not have counterparts in lines emitted above 8 x 10-5 K. Bright compact sources only seen in the transition region lines are investigated. These sources can have lifetimes of up to several days and are located in the vicinity of sunspots. We study the variability of active region sources on time scales from 30 sec to several days. We find oscillatory behaviour of Hei and Ov line intensities in an active region on time scales of 5-10 min. Title: EUV Observations of a Macrospicule: Evidence for Solar Wind Acceleration? Authors: Pike, C. D.; Harrison, R. A. Bibcode: 1997SoPh..175..457P Altcode: We present a unique observation of a macrospicule, recorded in extreme ultraviolet light on 11 April 1996, using the Coronal Diagnostic Spectrometer (CDS) on board the Solar and Heliospheric Observatory (SOHO). The observation was made by chance as part of a daily, large-area mapping sequence. Although the feature has some characteristics of the class of events which have become known as X-ray jets, we argue that the feature observed here is a macrospicule. This being the case, the observation demonstrates several new features of macrospicule observation. Emission is detected from the macrospicule to temperatures of 1 million degrees. In addition, some footpoint structure is detected at the root of the macrospicule, and the edges or sides of the macrospicule appear brighter than the central regions. A velocity analysis shows high speed flows within the macrospicule. Velocities are seen to increase with altitude until a plateau is achieved. Coincident with this, there is evidence for emission line narrowing. The significance of these observations for solar wind acceleration processes is discussed. Title: EUV Blinkers: The Significance of Variations in the Extreme Ultraviolet Quiet Sun Authors: Harrison, Richard A. Bibcode: 1997SoPh..175..467H Altcode: A search for microflare activity in the extreme ultraviolet (EUV) quiet Sun using the Coronal Diagnostic Spectrometer (CDS) aboard the Solar and Heliospheric Observatory (SOHO) spacecraft has not resulted in the identification of microflare activity, but has resulted in the identification of a hitherto unknown phenomenon: enhancements of a factor of 2-3 in the flux of transition region lines at network junctions. A total of some 6 hours of observation of 5 different target areas showed this `blinker' activity at each area, with durations ranging from 1 to 30 min and averaging 13 min, and thermal energy content of order 10-6 that of a `standard' flare. Assuming that the observations are of typical quiet Sun, and projecting these data to predict a distribution of these events over the entire Sun, the total thermal energy content of these `blinkers' is insignificant when compared to the energy required to heat the corona. The nature of these events and their significance are discussed in this paper. Title: High-Velocity Flows in an Active Region Loop System Observed with the Coronal Diagnostic Spectrometer (Cds) on SOHO Authors: Brekke, P.; Kjeldseth-Moe, O.; Harrison, R. A. Bibcode: 1997SoPh..175..511B Altcode: EUV spectra of coronal loops above an active region show clear evidence of strong dynamical activity. We present an example where the Ov 629 Å line, formed at 240 000 K, is shifted from its reference position corresponding to line-of-sight velocities greater than 50 km s-1 with the shift extending over a large fraction of a loop. The observations were made with the Coronal Diagnostic Spectrometer (CDS) on the Solar and Heliospheric Observatory (SOHO), and are from active region NOAA 7981 on the east solar limb on 27 July 1996. An animation has been prepared showing the variation of the shift or flow velocity along the loop. This animation is to be found on the enclosed CD-ROM and gives a clear impression of the dynamical condition present in the loop. The appearance of the loop system in different lines formed over a range in temperature as well as the observed dynamics indicates that loops at different temperatures are not closely co-located. Finally, the results are discussed and related to mechanisms that may cause line shifts. Title: Solar physics Authors: Harrison, R. A. Bibcode: 1997Obs...117..279H Altcode: No abstract at ADS Title: First Observations of Coronal Hole Structure and Evolution Using Soho-Cds Authors: Insley, J. E.; Moore, V.; Harrison, R. A. Bibcode: 1997SoPh..175..437I Altcode: We report on initial observations of coronal holestructure and evolution by the Coronal Diagnostic Spectrometer (CDS) instrument on board the Solar and Heliospheric Observatory (SOHO). The data show that there is coronal activity on time scales of tens of minutes, manifested as brightenings at chromospheric network cell junctions in extreme ultraviolet (EUV) wavelengths. There are also significant differences in structure seen in different wavelengths in coronal holes. Finally, we show coronal hole EUV spectra and compare them to quiet-Sun spectra, also taken by CDS. Title: IACG Campaign III: solar events and their manifestation in interplanetary space and in geospace Authors: Harrison, R. A. Bibcode: 1997AdSpR..20..623H Altcode: In Spring 1994 the Inter Agency Consultative Group Campaign III was set up at a kick-off meeting in Sagamihara, Japan. The basic idea of Campaign III was to coordinate solar, interplanetary and near-Earth spacecraft in an effort to link solar and near-Earth observations relating to activity such as solar mass ejections, and features such as co-rotating interaction regions. The Campaign was split into two basic activities, namely (i) studies of the onset of mass ejections, and (ii) studies of the effects of mass ejections and other solar phenomena at the Earth. The onset of the Campaign activities was effectively linked to the launch date of the Solar and Heliospheric Observatory (SOHO) spacecraft, since most of the planned activities centred on use of SOHO data linked to other spacecraft. SOHO was launched in December 1995 and the onset of full scientific operations was in March/April 1996. At the time of writing the more complex, time consuming multiple instrument operations such as the ones required for the IACG campaign have not been run, though pilot studies between selected instruments have been performed. Thus, we have preliminary observations relevant to the Campaign, and we anticipate the full campaign tobe run on several occasions before the end of the year. In this paper, we report on the IACG Campaign III concept and on the preliminary results from the pilot studies. Title: Wave Propagation in the Chromosphere and Transition Region: Where Have All the Shock Waves Gone? Authors: Fleck, B.; Steffens, S.; Deubner, F. -L.; Wilhelm, K.; Harrison, R.; Gurman, J. Bibcode: 1997SPD....28.0120F Altcode: 1997BAAS...29..882F We present first results from a joint observing program (SOHO JOP 26) involving SUMER, CDS and EIT on SOHO, coordinated with ground-based observations at the Vacuum Tower Telescope at Iza{\ n}a, Tenerife. The objective of this study is to characterize the wave propagation properties in the solar atmosphere, from the photosphere through the chromosphere up into the transition region. Particular emphasis is laid on the 3-min shock waves observed in the Ca II K line. How do they impact the transition region and what signature do they leave there and in the lower corona? The ground-based measurements comprise high resolution time series (both filtergrams and spectrograms) in Ca II K, Hα and Mgb_2. With SUMER we ran four sequences covering different temperature regimes: a) O I 1302, O I 1306, Si II 1309, C I 1311, C II 1334, C II 1335, b) Si I 1256, N V 1242, O V 629 c) He I 584, C III 1175, O I 1152, d) H I 1025, O VI 1031, O VI 1037. With CDS we took spectral time series in O VI 554, He I 584, He II 607, Mg IX 368, and O V 629 as well as wide-slit (90x240'') ``movies'' in He I 584, Mg IX 368 and O V 629, while EIT ran sub-field high cadence sequences in He II 304. Title: Uses of microchannel plate intensified detectors for imaging applications in the X-ray, EUV and visible wavelength regions Authors: Read, P. D.; Carter, M. K.; Pike, C. D.; Harrison, R. A.; Kent, B. J.; Swinyard, B. M.; Patchett, B. E.; Redfern, R. M.; Shearer, A.; Colhoun, M. Bibcode: 1997NIMPA.392..359R Altcode: The Rutherford Appleton Laboratory Photon Counting Detector (RALPCD) has been refined to meet project requirements for a flexible imaging arrangement with applications at X-ray, EUV and visible wavelengths. The basic detector design comprises commercially available high gain microchannel plate intensifiers fibre optically coupled to CID or CCD cameras, to form a modular detector arrangement with the appropriate RAL detection and centroiding software. Frames of data from the cameras are detected and centroided in a Transputer or C40 parallel processor array where correction algorithms use look up tables to produce pattern free images at high resolution. Data from completed applications are used to illustrate the performance and future advances are discussed. Title: The Non-Uniformity in the Sunspot Transition Region Authors: Brynildsen, N.; Brekke, P.; Fredvik, T.; Haugan, S. V. H.; Kjeldseth-Moe, O.; Maltby, P.; Harrison, R. A.; Rimmele, T.; Wilhelm, K. Bibcode: 1997ESASP.404..257B Altcode: 1997cswn.conf..257B No abstract at ADS Title: Preface Authors: Harrison, Richard Bibcode: 1997CIBu..140....7H Altcode: No abstract at ADS Title: Preface Authors: Harrison, Richard Bibcode: 1997CIBu..138....5H Altcode: No abstract at ADS Title: Ground and Space-Based Studies of Solar Wind Acceleration Authors: Breen, A. R.; Coles, W. A.; Grall, R. R.; Harrison, R. A.; McKenzie, J. F.; Markkanen, J.; Moran, P. J.; Varley, C. A.; Williams, P. J. S. Bibcode: 1997ESASP.404..223B Altcode: 1997cswn.conf..223B No abstract at ADS Title: Transition Region Velocities and Line Profiles in the Sunspot Region 7981 Authors: Brynildsen, N.; Brekke, P.; Fredvik, T.; Haugan, S. V. H.; Kjeldseth-Moe, O.; Maltby, P.; Harrison, R. A.; Pike, C. D.; Rimmele, T. Thompson, W. T.; Wilhelm, K. Bibcode: 1997ESASP.404..251B Altcode: 1997cswn.conf..251B No abstract at ADS Title: One Year of CDS: Highlights from Observations using the Coronal Diagnostic Spectrometer on SOHO Authors: Harrison, R. A. Bibcode: 1997ESASP.404....7H Altcode: 1997soho....5....7H; 1997cswn.conf....7H No abstract at ADS Title: Active Region Blinkers: Transient Events in the Solar Atmosphere Authors: Walsh, R. W.; Ireland, J.; Harrison, R. A.; Priest, E. R. Bibcode: 1997ESASP.404..717W Altcode: 1997cswn.conf..717W No abstract at ADS Title: Periodicities in Active Regions Authors: Ireland, J.; Walsh, R. W.; Harrison, R. A.; Priest, E. R. Bibcode: 1997ESASP.404..433I Altcode: 1997cswn.conf..433I No abstract at ADS Title: CDS Observations of the Connection Between Line Intensity and Doppler Shift in the Active Region NOAA 7981 Authors: Fredvik, T.; Brynildsen, N.; Maltby, P.; Kjeldseth-Moe, O.; Brekke, P.; Haugen, S. V. H.; Harrison, R. A. Bibcode: 1997ESASP.404..391F Altcode: 1997cswn.conf..391F No abstract at ADS Title: Flows with High Velocities in an Active Region Loop Observed with the Coronal Diagnostic Spectrometer Authors: Kjeldseth-Moe, O.; Brekke, P.; Harrison, R. A. Bibcode: 1997ESASP.404..457K Altcode: 1997cswn.conf..457K No abstract at ADS Title: CME Onset Studies Authors: Harrison, R. A. Bibcode: 1997ESASP.404...85H Altcode: 1997cswn.conf...85H; 1997soho....5...85H No abstract at ADS Title: First Results from SOHO on Waves Near the Solar Transition Region Authors: Steffens, S.; Deubner, F. -L.; Fleck, B.; Wilhelm, K.; Schuhle, U.; Curdt, W.; Harrison, R.; Gurman, J.; Thompson, B. J.; Brekke, P.; Delaboudiniere, J. -P.; Lemaire, P.; Hessel, B.; Rutten, R. J. Bibcode: 1997ASPC..118..284S Altcode: 1997fasp.conf..284S We present first results from simultaneous observations with the CDS, EIT and SUMER instruments {please see Solar Physics 162 (1995) for a description of the instruments} onboard SOHO and the VTT at Tenerife. Our aim is to study the wave propagation, shock formation, and transmission properties of the upper chromosphere and transition region. The preliminary results presented here include the variation of velocity power spectra with height, difference in power between internetwork and network regions, and variations in mean flows displayed by different spectral lines. Title: The Net Redshifts in EUV Emission Lines and the Connection Between Intensity and Doppler Shift Authors: Brynildsen, N.; Fredvik, T.; Maltby, P.; Kjeldseth-Moe, O.; Brekke, P.; Haugan, S. V. H.; Harrison, R. A.; Wilhelm, K. Bibcode: 1997ESASP.404..263B Altcode: 1997cswn.conf..263B No abstract at ADS Title: EUV Line Emission and Time Dependence in the Sunspot Region NOAA 7981 Authors: Brynildsen, N.; Brekke, P.; Fredvik, T.; Haugan, S. V. H.; Kjeldseth-Moe, O.; Maltby, P.; Harrison, R. A.; Pike, C. D.; Rimmele, T.; Thompson, W. T.; Wilhelm, K. Bibcode: 1997ESASP.404..245B Altcode: 1997cswn.conf..245B No abstract at ADS Title: Temporal Variability in the Quiet Sun Transition Region Authors: Wikstoøl, Ø.; Hansteen, V. H.; Brynildsen, N.; Maltby, P.; Kyeldseth-Moe, O.; Harrison, R. A.; Wilhelm, K.; Tarbell, T. D.; Scherrer, P. H. Bibcode: 1997ESASP.404..733W Altcode: 1997cswn.conf..733W No abstract at ADS Title: Properties of Brightenings Seen in CDS Movies Authors: Rüedi, I.; Brkovic, A.; Solanki, S. K.; Harrison, R.; Fludra, A.; Huber, M. C. E.; Stenflo, J. O.; Stucki, K. Bibcode: 1997ESASP.404..641R Altcode: 1997cswn.conf..641R No abstract at ADS Title: High-Resolution Observations of the Extreme Ultraviolet Sun Authors: Harrison, R. A.; Fludra, A.; Pike, C. D.; Payne, J.; Thompson, W. T.; Poland, A. I.; Breeveld, E. R.; Breeveld, A. A.; Culhane, J. L.; Kjeldseth-Moe, O.; Huber, M. C. E.; Aschenbach, B. Bibcode: 1997SoPh..170..123H Altcode: This paper presents first results of the Coronal Diagnostic Spectrometer (CDS) recently launched aboard the Solar and Heliospheric Observatory (SOHO). CDS is a twin spectrometer, operating in the extreme ultraviolet range 151-785 Å. Thus, it can detect emission lines from trace elements in the corona and transition region which will be used to provide diagnostic information on the solar atmosphere. In this paper, we present early spectra and images, to illustrate the performance of the instrument and to pave the way for future studies. Title: Flows and Dynamics in the Corona Observed with the Coronal Diagnostic Spectrometer (cds) Authors: Brekke, P.; Kjeldseth-Moe, O.; Brynildsen, N.; Maltby, P.; Haugan, S. V. H.; Harrison, R. A.; Thompson, W. T.; Pike, C. D. Bibcode: 1997SoPh..170..163B Altcode: EUV spectra obtained with the Coronal Diagnostic Spectrometer (CDS) on the Solar and Heliospheric Observatory (SOHO) show significant flows of plasma in active region loops, both at coronal and transition region temperatures. Wavelength shifts in the coronal lines Mgix 368 Å and Mgx 624 Å corresponding to upflows in the plasma reaching velocities of 50 km s-1 have been observed in an active region. Smaller velocities are detected in the coronal lines Fexvi 360 Å and Sixii 520 Å. Flows reaching 100 km s-1 are observed in spectral lines formed at transition region temperatures, i.e., Ov 629 Å and Oiii 599 Å, demonstrating that both the transition region and the corona are clearly dynamic in nature. Some high velocity events show even higher velocities with line profiles corresponding to a velocity dispersion of 300-400 km s-1. Even in the quiet Sun there are velocity fluctuations of 20 km s-1 in transition region lines. Velocities of the magnitude presented in this paper have never previously been observed in coronal lines except in explosive events and flares. Thus, the preliminary results from the CDS spectrometer promise to put constraints on existing models of the flows and energy balance in the solar atmosphere. The present results are compared to previous attempts to observe flows in the corona. Title: Wave Propagation in the Chromosphere and Transition Region Authors: Steffens, S.; Deubner, F. -L.; Fleck, B.; Wilhelm, K.; Harrison, R.; Gurman, J. Bibcode: 1997ESASP.404..679S Altcode: 1997cswn.conf..679S No abstract at ADS Title: Application of Spectroscopic Diagnostics to Early Observations with the SOHO Coronal Diagnostic Spectrometer Authors: Mason, H. E.; Young, P. R.; Pike, C. D.; Harrison, R. A.; Fludra, A.; Bromage, B. J. I.; Del Zanna, G. Bibcode: 1997SoPh..170..143M Altcode: The Coronal Diagnostic Spectrometer (CDS) has as a scientific goal the determination of the physical parameters of the solar plasma using spectroscopic diagnostic techniques. Absolute intensities and intensity ratios of the EUV spectral emission lines can be used to obtain information on the electron density and temperature structure, element abundances, and dynamic nature of different features in the solar atmosphere. To ensure that these techniques are accurate it is necessary to interface solar analysis programs with the best available atomic data calculations. Progress is reported on this work in relation to CDS observations. Title: Microwave and UV observations of filaments with SOHO and the VLA Authors: Alissandrakis, C. E.; Drago, F.; Bastian, T.; Bocchialini, K.; Delaboudiniere, J. -P.; Lemaire, P.; Vial, J. -C.; Harrison, R. A.; Thompson, B. Bibcode: 1997ASPC..118..289A Altcode: 1997fasp.conf..289A Observations performed in coordination between SOHO instruments and ground-based observatories offer the unique possibility to derive information simultaneously in several wavelengths formed at different altitudes and/or temperatures in the solar atmosphere. The SUMER and CDS spectrometers, the imaging telescope EIT aboard SOHO, and the VLA provide complementary information in the UV and the radio ranges. We illustrate such a coordination with observations of filaments in the transition region, performed in July 1996. The observations in the UV between 10(4) and 10(6) K provide the differential emission measure as a function of temperature; this can be used to compute the expected brightness temperature in the microwave range and check models of the filament-corona transition region. Title: Extreme ultraviolet observations of the solar corona: first results from the coronal diagnostic spectrometer on SOHO Authors: Harrison, R. A.; Fludra, A.; Sawyer, E. C.; Culhane, J. L.; Norman, K.; Poland, A. I.; Thompson, W. T.; Kjeldseth-Moe, O.; Aschenbach, B.; Huber, M. C. E.; Gabriel, A. H.; Mason, H. E. Bibcode: 1997AdSpR..20.2239H Altcode: We present first results from the Coronal Diagnostic Spectrometer (CDS) aboard the ESA/NASA Solar and Heliospheric Observatory (SOHO). CDS is a double spectrometer operating in the 151-785 A˚ range. This region of the solar spectrum is rich in emission lines from trace elements in the solar atmosphere, which can be used to derive diagnostic information on coronal and transition region plasma. Early spectra are presented and well identified lines are listed. In addition, examples of images in selected wavelength ranges are shown, for a prominence, a loop system and a bright point, demonstrating well the power of such extreme ultraviolet observations. Title: Coronal Magnetic Storms: a New Perspective on Flares and the `Solar Flare Myth' Debate Authors: Harrison, Richard A. Bibcode: 1996SoPh..166..441H Altcode: Recently Gosling (1993) examined the interplanetary consequences of solar activity, and suggested that the coronal mass ejection (CME) was the prime driver of most disturbances (i.e., interplanetary shocks, high-energy particles, geomagnetic storms, etc.) and that the solar flare was relatively unimportant in this context. He coined the phrase `Solar Flare Myth'. Since that paper there has been much debate on the origin of interplanetary disturbances - most people sitting squarely in the flare or CME camp. Švestka (1995) has attacked Gosling's conclusions on the grounds that it is misleading to ignore the flare, and that past flare classifications were perfectly adequate for explaining the observations described by Gosling. This paper is a comment on Švestka's report and an attempt to put the Solar Flare Myth into perspective - indeed it is an attempt to view the solar flare/CME phenomena in a more constructive light. Title: Coordinated SOHO Observations of Polar Plumes Authors: Deforest, C. E.; Scherrer, P. H.; Tarbell, T.; Harrison, R. A.; Fludra, A.; Delaboudiniere, J. P.; Gurman, J. B.; Wilhelm, K.; Lemaire, P.; Hassler, D. M.; Kohl, J. L.; Noci, G.; Fineschi, S.; Brueckner, G. E.; Howard, R. A.; Cyr, O. C. St. Bibcode: 1996AAS...188.4909D Altcode: 1996BAAS...28R.898D On 7 and 8 March 1996, SOHO instruments engaged in their first joint science operation, a 12-hr observation of polar plumes over the South polar coronal hole. The observing mini-campaign included observations from SOHO, other spacecraft, and ground-based observatories. Contributing SOHO instruments -- in order of altitude, MDI, CDS, SUMER, EIT, UVCS, and LASCO -- made overlapping, simultaneous observations of plume structures from the photosphere out to the LASCO C3 limit of 32 solar radii. MDI provided line-of-sight surface magnetograms with a one-min cadence and 0.6 arcsec resolution; CDS, SUMER, and EIT supplied temperature-sensitive images of the lower corona with varying cadences and resolutions; UVCS measured fluctuations in Ly B intensity across the coronal hole with a one-min cadence at 1.4 R0; and LASCO imaged the entire corona out to 30 R0 in various visible passbands. Plume footpoints in the lower corona are observed by EIT and CDS to vary by a factor of two in EUV brightness with a timescale of tens of minutes, while the structures above are (as as been previously observed) quiescent on at least a ten-hr time scale. We present preliminary results of cross-instrument analysis of the observed plumes, and suggest how this and similar future data sets can be used to constrain quiet-sun wind acceleration and coronal heating models for the coronal hole. This research is supported by the SOI-MDI NASA contract NAG5-3077 at Stanford University. SOHO is project of international cooperation between NASA and ESA. Title: TRACE: the Transition Region and Coronal Explorer Authors: Schrijver, C.; Title, A.; Acton, L.; Bruner, M.; Fischer, R.; Golub, L.; Harrison, R.; Lemen, J.; Rosner, R.; Scharmer, G.; Scherrer, P.; Strong, K.; Tarbell, T.; Wolfson, J. Bibcode: 1996AAS...188.6704S Altcode: 1996BAAS...28..934S The TRACE mission is designed to obtain images of the solar transition region and corona of unprecedented quality. With these images we will be able to explore quantitatively the connections between the photospheric magnetic field and the associated hot and tenuous structures in the outer atmosphere. The TRACE telescope has an aperture of 30 cm, and will observe an 8.5 x 8.5 arcminute field of view with a resolution of one arcsecond. Finely tuned coatings on four quadrants on the primary and secondary normal--incidence mirrors will allow observations in narrow EUV and UV spectral bands. The passbands are set to Fe IX, XII, and XV lines in the EUV band, while filters allow observations in C IV, Ly alpha , and the UV continuum using the UV mirror quadrant. The data thus cover temperatures from 10(4) K up to 10(7) K. The Sun--synchronous orbit allows long intervals of uninterrupted viewing. Observations at different wavelengths can be made in rapid succession with an alignment of 0.1 arcsec. Coordinated observing with TRACE, SoHO and YOHKOH will give us the first opportunity to observe all temperature regimes in the solar atmosphere, including magnetograms, simultaneously from space. TRACE is currently scheduled to be launched in October 1997. More information can be found on the web at ``http://pore1.space.lockheed.com/TRACE/welcome.html''. Title: High Velocity Event Observed with CDS on SOHO Authors: Kjeldseth-Moe, O.; Brynildsen, N.; Brekke, P.; Harrison, R. A. Bibcode: 1996AAS...188.3714K Altcode: 1996BAAS...28..880K The Coronal Diagnostic Spectrometer, CDS, on SOHO has observed its first strong High Velocity Event. The event occurred on 22 March 1996 at approximately 13.36 UT and was located in the leg of an active region loop. The spectral signature is extremely wide emission lines corresponding to a velocity dispersion of approximately 300-450 km/s. As measured in the 386 A line from Mg IX, the emission also seems shifted in wavelength with a redshift corresponding to 65 km/s. The intensity contrast in the line is a factor 2 compared to the surrounding areas. The spatial extent is small, less than or corresponding to the angular resolution of CDS of 4". The event occur in all available lines from He I to Fe XV, i.e. over a temperature range from 10 000 K to 2.2 MK. This is a new result which has not been reported before. The relation of this type of event to the well studied explosive events is discussed. Title: The Coronal Diagnostic Spectrometer for the Solar and Heliospheric Observatory: experiment description and calibration. Authors: Harrison, R. A.; Kent, B. J.; Sawyer, E. C.; Hollandt, J.; Kuhne, M.; Paustian, W.; Wende, B.; Huber, M. C. E. Bibcode: 1996Metro..32..647H Altcode: The Coronal Diagnostic Spectrometer (CDS) to be flown aboard the ESA/NASA Solar and Heliospheric Observatory (SOHO) is designed to probe the solar atmosphere through the detection of spectral emission lines in the extreme ultraviolet (EUV) wavelength range 15 nm to 80 nm. By observing the absolute and relative radiance of selected lines and line profiles, one is able to derive temperature, density, flow and abundance information for the plasmas in the solar atmosphere. Spatial and temporal resolutions of down to a few arcseconds and 1 second, respectively, allow such studies to be made within the fine-scale structure of the solar corona. Simultaneous coverage of large-wavelength bands provides the capability for simultaneously observing the properties of plasmas across the wide temperature ranges of the solar atmosphere. The pre-launch calibration is achieved through the use of a hollow cathode discharge source which is used as a transfer standard to allow calibration of the CDS against the primary standard of the BESSY electron storage ring. By the use of different selected gases in the discharge tube, each of the detector wavelength intervals in the CDS can be covered adequately. The pre-delivery calibration of the CDS has been performed and some results are shown. Title: Preface Authors: Harrison, Richard Bibcode: 1996CIBu..135....4H Altcode: No abstract at ADS Title: The nature of solar flares associated with coronal mass ejection. Authors: Harrison, R. A. Bibcode: 1995A&A...304..585H Altcode: An analysis is presented of solar X-ray flares associated with coronal mass ejections through the period 1986-1987. The nature of the flares apparently associated with mass ejection is explored. In particular the relationships between flare duration and intensity and the association with mass ejection are investigated. We believe that this study tackles the flare-CME analysis in a way that is uniquely unbiased. Past studies of a similar nature are discussed and a criticism of their approach is given. In particular, the author believes that the continual bias toward the so-called Long Duration Events and the brightest flares is misleading. The analysis supports the view that the flare and CME are signatures of the same magnetic "disease", that is, they represent the responses in different parts of the magnetic struture, to a particular activity; they do not drive one another but are closely related. The present statistical analysis allows a chance association to be given for a mass ejection event when an X-ray flare is observed. The use of such information in the prediction of geomagnetic activity generated when mass ejecta interact with the Earth is discussed. Title: The Coronal Diagnostic Spectrometer for the Solar and Heliospheric Observatory: experiment description and calibration Authors: Harrison, R. A.; Kent, B. J.; Sawyer, E. C.; Hollandt, J.; K Hne, M.; Paustian, W.; Wende, B.; Huber, M. C. E. Bibcode: 1995Metro..32..647H Altcode: No abstract at ADS Title: The Coronal Diagnostic Spectrometer for the Solar and Heliospheric Observatory Authors: Harrison, R. A.; Sawyer, E. C.; Carter, M. K.; Cruise, A. M.; Cutler, R. M.; Fludra, A.; Hayes, R. W.; Kent, B. J.; Lang, J.; Parker, D. J.; Payne, J.; Pike, C. D.; Peskett, S. C.; Richards, A. G.; Gulhane, J. L.; Norman, K.; Breeveld, A. A.; Breeveld, E. R.; Al Janabi, K. F.; Mccalden, A. J.; Parkinson, J. H.; Self, D. G.; Thomas, P. D.; Poland, A. I.; Thomas, R. J.; Thompson, W. T.; Kjeldseth-Moe, O.; Brekke, P.; Karud, J.; Maltby, P.; Aschenbach, B.; Bräuninger, H.; Kühne, M.; Hollandt, J.; Siegmund, O. H. W.; Huber, M. C. E.; Gabriel, A. H.; Mason, H. E.; Bromage, B. J. I. Bibcode: 1995SoPh..162..233H Altcode: The Coronal Diagnostic Spectrometer is designed to probe the solar atmosphere through the detection of spectral emission lines in the extreme ultraviolet wavelength range 150 - 800 å. By observing the intensities of selected lines and line profiles, we may derive temperature, density, flow and abundance information for the plasmas in the solar atmosphere. Spatial and temporal resolutions of down to a few arcseconds and seconds, respectively, allow such studies to be made within the fine-scale structure of the solar corona. Futhermore, coverage of large wavelength bands provides the capability for simultaneously observing the properties of plasmas across the wide temperature ranges of the solar atmosphere. Title: Book-Review - the High Latitude Heliosphere Authors: Marsden, R. G.; Harrison, R. A. Bibcode: 1995Obs...115..346M Altcode: No abstract at ADS Title: Coronal Diagnostic Spectrometer: an extreme-ultraviolet spectrometer for the Solar and Heliospheric Observatory Authors: Kent, Barry J.; Harrison, Richard A.; Sawyer, Eric C.; Hayes, R. W.; Richards, Anthony G.; Culhane, John L.; Norman, K.; Breeveld, A. A.; Thomas, P. D.; Poland, Arthur I.; Thomas, Roger J.; Thompson, William T.; Aschenbach, Bernd R.; Braeuninger, Heinrich W.; Kjeldseth-Moe, O.; Kuehne, Mikhael; Hollandt, J.; Paustian, W.; Bromage, B. J. Bibcode: 1995SPIE.2517...12K Altcode: The coronal diagnostic spectrometer is designed to probe the solar atmosphere through the detection of spectral emission lines in the extreme ultraviolet wavelength range 15.0 - 80.0 nm. By observing the intensities of selected lines and line profiles, it is possible to derive temperature, density, flow, and abundance information for the plasmas in the solar atmosphere. Spatial resolution down to a few arcseconds and temporal resolution of seconds, allows such studies to be made within the fine-scale structure of the solar corona. Furthermore, coverage of a large wavelength band provides the capability for simultaneously observing the properties of plasma across the wide temperature ranges of the solar atmosphere. The CDS design makes use of a Wolter-Schwarzschild II telescope which simultaneously illuminates two spectrometer systems, one operating in normal incidence the other in grazing incidence. In this paper we describe the salient features of the design of the CDS instrument and discuss the performance characteristics of CDS as established through pre-delivery test and calibration activities. Title: The differential rotation of the corona as indicated by coronal holes Authors: Insley, J. E.; Moore, V.; Harrison, R. A. Bibcode: 1995SoPh..160....1I Altcode: The rotation of the corona can be determined either directly by using Doppler methods or indirectly by using tracers, i.e., structures within the corona. In this study the rotational characteristics of the corona are determined using coronal holes as tracers, for the period 1978-1991. The coronal data used here are from an atlas of coronal holes mapped in HeI 10830 å data. A comparison is made between our results and previous determinations of the coronal rotation rate, e.g., by Sime (1986), using white-light K-coronameter observations, by Timothy, Krieger, and Vaiana (1975), using soft X-ray observations, and by Shelke and Pande (1985) and Navarro-Peralta and Sanchez-Ibarra (1994), using HeI 10830 å data. For the atlas of coronal holes used in this study the nature of the coronal hole distributions in number and latitude, in yearly averages, has been determined. These distributions show that at solar minimum the polar coronal holes dominate and the few non-polar holes are confined to a narrow band near the equator. At solar maximum, however, mid-latitude coronal holes dominate, with a large spread in latitudes. Given these distributions we consider the differential rotation data only as an average over a solar cycle. This removes spurious effects caused by having only a small number of coronal holes contributing to the results, or by having a narrow latitude band for the observations, thus limiting the results to that narrow latitude band. By considering these coronal holes as tracers of the differential rotation we show that the mid-latitude corona rotates more rigidly than the photosphere, but still exhibits significant differential rotation, with an equatorial rate of 13.30 ± 0.04° day−1, and at 45° latitude a rate of 12.57 ± 0.13° day−1. These results are comparable, within errors, to the Sime (1986) results which have an equatorial rate of approximately 13.2 ± 0.2° day−1 and a rate of approximately 12.9 ± 0.3° day−1 at 45° latitude. Title: Preface Authors: Harrison, Richard Bibcode: 1995CIBu..134....8H Altcode: No abstract at ADS Title: Mars Microrover navigation: performance evaluation and enhancement. Authors: Matthies, L.; Gat, E.; Harrison, R.; Wilcox, B.; Volpe, R.; Litwin, T. Bibcode: 1995AuRob...2..291M Altcode: The Mars Pathfinder spacecraft will carry a rover to explore the immediate vicinity of the lander. To assess the capabilities of the rover, as well as to set priorities for future rover research, it is essential to evaluate the performance of its autonomous navigation system as a function of terrain characteristics. The authors have constructed a new Microrover testbed. In this paper, the authors outline current plans for Mars exploration over the next decade, summarize the design of the lander and rover for the 1996 Pathfinder mission, and introduce a decomposition of rover navigation into four major functions: goal designation, rover localization, hazard detection and path selection. They then describe the Pathfinder approach to each function, present results to date of evaluating the performance of each function and outline their approach to enhancing performance for future missions. The results show key limitations in the quality of rover localization, the speed of hazard detection and the ability of behaviour control algorithms for path selection to negotiate the rock frequencies likely to be encountered on Mars. The facilities, methodologies and, to some extent, the specific performance results presented in this paper provide valuable examples for efforts to evaluate robotic vehicle performance in other applications. Title: Preface Authors: Harrison, Richard Bibcode: 1995CIBu..133...59H Altcode: No abstract at ADS Title: Preface Authors: Harrison, Richard Bibcode: 1995CIBu..132....2H Altcode: No abstract at ADS Title: The Inter Agency Consultative Group campaign to study coronal mass ejection onsets Authors: Harrison, R. A. Bibcode: 1994ESASP.373..355H Altcode: 1994soho....3..355H No abstract at ADS Title: Book Review: Infrared solar physics / Kluwer, 1993 Authors: Harrison, R. A. Bibcode: 1994Obs...114..189H Altcode: 1994Obs...114..189R No abstract at ADS Title: A statistical study of the coronal mass ejection phenomenon Authors: Harrison, R. A. Bibcode: 1994AdSpR..14d..23H Altcode: 1994AdSpR..14...23H The coronal mass ejection (CME) phenomenon represents a major component of the evolution of the solar corona, yet the mechanisms leading to such events remain something of a mystery. To understand the onset phase of these ejecta, many studies have focused on the relationship between CMEs and other, apparently related activity. A typical CME occurs on a very large spatial scale and involves the expulsion of up to 1012kg of matter, and the release of up to 1025J from the coronal magnetic field. A solar flare is an explosive event at the base of the atmosphere involving the release of up to 1025J of energy. Since there is an apparent association between these two phenomena and the time-scale for flares is comparable to that of the acceleration phase of the mass ejections, the questions arise as to what precise relationship exists between the two and what does this indicate about the physics of each. Many earlier studies of this kind were compromised by unfortunate assumptions, poor data coverage or instrumental limitations. This study attempts to identify purely formal correlations between parameters relating to flare and mass ejection observations through the period 1986-1987. In spite of a strong association between flares and CME onsets, we find that no single type of flare shows a preferred association with mass ejections, and the relative locations and timing of the two phenomena show no systematic ordering. Title: On the potential of interplanetary scintillation for predicting geomagnetic activity Authors: Hapgood, Mike; Harrison, Richard Bibcode: 1994GeoRL..21..637H Altcode: A survey of IPS, geomagnetic and inter-planetary medium data has been used to interpret the weak correlation between IPS data and geomagnetic activity. Our results indicate that: (i) we can use IPS data to predict the maximum possible level of geomagnetic activity, given the state of the solar wind; but (ii) to predict the actual level of activity we also require an estimate the coupling between the solar wind and the magnetosphere. This is the first time that the potential (and the limitations) of IPS for predicting geomagnetic activity have been demonstrated quantitatively in a comprehensive survey. Title: The study of the solar wind using interplanetary scintillation observations from the MRAO, Cambridge, array. Authors: Moore, V.; Lucek, E. A.; Sime, D. G.; Harrison, R. A. Bibcode: 1994JBIS...47..164M Altcode: The daily monitoring of short time intensity fluctuations of astronomical radio sources by an array at the Mullard Radio Astronomy Observatory (MRAO), Cambridge, provides one of the few remote sensing techniques for studying the large scale structure of the near-Earth heliosphere. After an introduction to the interplanetary scintillation (IPS) technique the authors review the overall character of the IPS results for 1991. As the corona is the source of the solar wind the authors indicate how large scale changes in the solar corona in 1991, from a near maximum to a more minimum like structure, were reflected in the IPS data. They also show, by way of a case study for two discrete events, how the MRAO IPS data may be used to investigate the solar sources and subsequent geomagnetic response to specific interplanetary plasma features. Title: A characterization of discrete solar wind events detected by interplanetary scintillation mapping Authors: Moore, V.; Harrison, R. A. Bibcode: 1994JGR....99...27M Altcode: We examine the large-scale solar wind density and velocity characteristics which are associated with interplanetary disturbances detected by interplanetary scintillation (IPS) mapping. Our aim here is to characterize these remotely sensed events in order to provide a better foundation on which to consider both the origin of such phenomena and their influence on the near-Earth environment. We select those events from a list published by Hewish and Bravo (1986) that appear to be Earth crossing and consider the average density and velocity in the solar wind at the time. We find density (and often velocity) enhancements in association with the majority of these IPS events, though the changes are modest. Postevent conditions commonly show a slight velocity increase and density decrease with respect to preevent conditions. Title: Foreword Authors: Harrison, Richard Bibcode: 1994CIBu..130....2H Altcode: No abstract at ADS Title: A Daily Interplanetary Scintillation Activity Index and its Relation to Solar and Geomagnetic Activity Authors: Harrison, R. A.; Hapgood, M. A. Bibcode: 1994step.conf..269H Altcode: No abstract at ADS Title: International solar terrestrial energy programme and the UK participation Authors: Lester, M.; Coates, A. J.; Harrison, R. A.; Rees, D.; Roederer, J. G.; Rycroft, M. J.; Saunders, M. A. Bibcode: 1993SGeo...14..555L Altcode: The Solar Terrestrial Energy Programme (STEP) aims to improve our general understanding of how mass, energy and momentum are transferred between the various regions that form the Solar Terrestrial environment. STEP began in 1990 and will continue until 1997, during which time a number of major new spacecraft and ground-based projects will become operational. Six Working Groups form the basis of STEP, covering topics such as the Sun as a source of energy and disturbance, energy and mass transfer through the interplanetary medium and the magnetosphere-ionosphere system, ionosphere-thermosphere coupling and response to energy and momentum inputs, middle atmosphere responses to forcing from above and below, solar variability effects in the human environment, and informatics. A Royal Astronomical Society Geophysics Discussion meeting took place in March 1992 to draw to the attention of UK scientists the diverse nature of STEP and the opportunities offered by STEP. This paper consists of individual sections prepared by the speakers at the meeting and which cover most of the STEP Working Group topics. The main aims of each section are to provide a “benchmark” for the present status of the research area and to look ahead to the possible contributions that UK scientists can make during STEP. Title: An active solar prominence in 1.3 MM radiation Authors: Harrison, R. A.; Carter, M. K.; Clark, T. A.; Lindsey, C.; Jefferies, J. T.; Sime, D. G.; Watt, G.; Roellig, T. L.; Becklin, E. E.; Naylor, D. A.; Tompkins, G. J.; Braun, D. Bibcode: 1993A&A...274L...9H Altcode: We present new millimetre-wavelength observations of an active solar prominence. Observations made over a two-day period with the James Clerk Maxwell Telescope on Manna Kea, Hawaii, give a unique view in 1.3 mm radiation of the spectacular prominence that appeared on the west solar limb in the total solar eclipse of 11 July 1991. Title: Book Review: The sun: a laboratory for astrophysics / Kluwer, 1992 Authors: Harrison, R. A. Bibcode: 1993Obs...113...87H Altcode: 1993Obs...113...87S No abstract at ADS Title: The SOHO interdisciplinary science matrix. Authors: Harrison, Richard A.; Schultz, G. Bibcode: 1992ESASP.348..397H Altcode: 1992cscl.work..397H To pursue the goals of SOHO, we are required to compare and analyse data-sets from very different experiments. Such interdisciplinary studies require careful planning, prior to the observations, and involve complex analysis procedures. In recognition of this, the SOHO Coronal and Particle Working Group has initiated a study to provide an overview of the nature of such activities. The first results of this study are presented here. Title: The coronal diagnostic spectrometer for the Solar and Heliospheric Observatory. Authors: Harrison, Richard A.; Sawyer, Eric C. Bibcode: 1992ESASP.348...17H Altcode: 1992cscl.work...17H The Coronal Diagnostic Spectrometer is designed to probe the solar atmosphere through the analysis of spectral emission lines in the extreme ultraviolet wavelength range 150 - 800 Å. By observing the absolute and relative intensities of selected lines, and line profiles, one may derive temperature, density, flow and abundance information for the plasmas in the solar atmosphere. Simultaneous coverage of large wavelength bands combined with spatial and temporal resolutions of a few arc sec and down to 1 sec will provide a unique tool for pursuing the goals of SOHO. Title: Measurement of the Height of the Solar CO Layer During the 11 July 1991 Eclipse Authors: Clark, T. A.; Naylor, D. A.; Tompkins, G. J.; Lindsey, C. A.; Becklin, E. E.; Jefferies, J. T.; Harrison, R. A.; Roellig, T. L.; Carter, M.; Braun, D. C.; Watt, G. Bibcode: 1992AAS...181.8108C Altcode: 1992BAAS...24.1253C No abstract at ADS Title: Coronal mass ejecta and flares: a statistical study. Authors: Harrison, R. A.; Sime, D. G. Bibcode: 1992ESASP.346..289H Altcode: 1992ssts.rept..289H A typical solar coronal mass ejection (CME) occurs on a very large spatial scale and involves the expulsion of up to 1012kg, and the release of up to 1025J from the coronal magnetic field. A solar flare is an explosive event at the base of the atmosphere involving the release of up to 1025J of energy. Since there is an observed association between these two phenomena and the time-scale for flares is comparable to that of the acceleration phase of the mass ejections, the questions arise as to what precise relationship exists between the two and what does this indicate about the physics of each. This study attempts to identify purely formal correlations between parameters relating to flare and mass ejection observations through the period 1986-7. In spite of a strong association between flares and CME onsets, no single type of flare shows preferred association with mass ejections and the relative locations and timing of the two phenomena show no systematic ordering. Title: Detecting and tracking changes in solar wind conditions using interplanetary scintillation. Authors: Harrison, Richard A.; Hapgood, M. A.; Sime, D. G. Bibcode: 1992ESASP.346..207H Altcode: 1992ssts.rept..207H Using the recently refurbished 81.5 MHz radio telescope at Cambridge the authors are able to monitor the scintillation of ≡1000 radio sources to identify regions of excessive scintillation due to the passage of enhanced density fluctuations in the interplanetary medium. Analysis of whole sky scintillation maps to reveal individual events has met with modest success. However, the maps are adversely affected by noise and can be difficult to interpret. As a result the cause of such disturbances, perhaps in the form of mass ejection from the Sun, and their effects are difficult to determine. For comparisons to geomagnetic activity and for prediction of such activity, the use of a single index to describe regions within the map promises to avoid many of the difficulties presented by visual inspection. The use of such a global descriptor is also more appropriate for comparison with geomagnetic indices. We have developed such a scintillation activity index. Title: An interplanetary scintillation activity index. Authors: Harrison, R. A.; Hapgood, M. A.; Moore, V.; Lucek, E. A. Bibcode: 1992AnGeo..10..519H Altcode: 1992AnG....10..519H Using interplanetary scintillation (IPS) data obtained from the Cambridge 81.5 MHz array, the authors have developed an activity index in which they identify (i) discrete structures, most likely relating to transient density enhancements, and (ii) periodic activity, relating to co-rotating interplanetary structure. They find significant, yet weak correlations between the index and geomagnetic activity. Their results suggest that the persuit of such an index could result in a valuable tool for the prediction of geomagnetic events and highlight several potential future developments. Title: Extreme-infrared brightness profile of the solar chromosphere obtained during the total eclipse of 1991 Authors: Lindsey, C.; Jefferies, J. T.; Clark, T. A.; Harrison, R. A.; Carter, M. K.; Watt, G.; Becklin, E. E.; Roellig, T. L.; Braun, D. C.; Naylor, D. A. Bibcode: 1992Natur.358..308L Altcode: THE solar chromosphere is a thin layer of gas that is several thousand degrees hotter than the underlying photosphere, and responsible for most of the Sun's ultraviolet emission. The mechanism by which it is heated to temperatures exceeding 10,000 K is not understood. Millimetre and submillimetre radiometry can be used to obtain the chromospheric temperature profile, but the diffraction-limited resolution for the largest telescopes is at best 17 arcsec, or ~12,500 km at the Sun's distance. This is greater than the thickness of the quiet chromosphere itself. The total eclipse of July 1991, which passed over the Mauna Kea Observatory in Hawaii, provided a rare opportunity to make limb occultation observations with a large submillimetrewavelength telescope, the 15-m James Clerk Maxwell Telescope, and in this way we obtained a temperature profile in 1.3-mm radiation with ~300 km resolution at the Sun. Our observations indicate that spicules (magnetically entrained funnels of gas) reach a temperature of 8,000 K at 3,000-4,000 km above the photosphere, a temperature lower than those of many spicule models. Title: Hα Activity and Global X-Ray Luminosity Flaring on the Sun Authors: Pearce, G.; Harrison, R. A.; Bromage, B. J. I.; Pickering, A. G. M. Bibcode: 1992sers.conf..440P Altcode: No abstract at ADS Title: High resolution observations of solar ejecta. Authors: Harrison, Richard A. Bibcode: 1992ESASP.344...91H Altcode: 1992spai.rept...91H In the solar atmosphere, the ejection of matter occurs on a variety of spatial scales. Indeed, it is useful to regard the phenomenon within the framework of a spectrum. At one extreme one finds the huge, discrete events known as coronal mass ejecta, involving spatial scales of over one hundred thousand km and timescales of up to tens of minutes. At the other extreme one is concerned with the microscopic processes which accumulate to become the apparently continuous solar wind, involving spatial scales of, perhaps, much less than 1000 km and timescales of seconds. In the intermediate portions of the spectrum one finds the high velocity events which have been identified in the transition zone and, probably, in the corona with spatial scales of 1000 km or more and timescales of order tens of seconds. One also finds surge and spray activity as chromospheric matter is expelled high into the corona, with spatial scales ranging from one thousand to tens of thousands of km and timescales often of order minutes. The larger scale phenomena, such as the surges, sprays and coronal mass ejecta, often display intricate fine scale features and, no doubt, as the spatial resolution improves one will identify structure within the finer scale ejection phenomena. The author explores the need for understanding these ejection events, the need for high resolution observation of them and will discuss the use of SIMURIS in making such observations. Title: Book Review: Opening the frontiers in solar research / Pergamon, 1991 Authors: Machado, M. E.; Mattig, W.; Simon, G. W.; Harrison, R. A. Bibcode: 1992Obs...112...70F Altcode: No abstract at ADS Title: Design Rationale of the Solar Ultraviolet Network / Sun Authors: Dame, L.; Acton, L.; Bruner, M. E.; Connes, P.; Cornwell, T. J.; Curdt, W.; Foing, B. H.; Hammer, R.; Harrison, R.; Heyvaerts, J.; Karabin, M.; Marsch, E.; Martic, M.; Mattic, W.; Muller, R.; Patchett, B.; Roca-Cortes, T.; Rutten, R. J.; Schmidt, W.; Title, A. M.; Tondello, G.; Vial, J. C.; Visser, H. Bibcode: 1992ESOC...39..995D Altcode: 1992hrii.conf..995D No abstract at ADS Title: Preface Authors: Harrison, R. A.; Argent, C. R. Bibcode: 1992CIBu..125....3H Altcode: No abstract at ADS Title: The relationship between global X-ray luminosity and flaring on the sun Authors: Pearce, G.; Harrison, R. A.; Bromage, B. J. I.; Pickering, A. G. M. Bibcode: 1992A&A...253..601P Altcode: The relationship between solar global flaring activity and X-ray luminosity is investigated as part of a solar-stellar investigation. In keeping with previous suggestions, it is found that the rate of flaring on the sun is closely related to X-ray luminosity with a positive correlation. This is in contrast to relationships found on dMe stars, and can be interpreted in terms of flare activity both on a microscopic and macroscopic scale varying sympathetically, rather than macroscopic flare energy storage subduing smaller scale energy release. The microscopic activity has significance for outstanding problems such as coronal heating. Title: Cylindrical fabric-confined soil structures Authors: Harrison, Richard A. Bibcode: 1992ecos.proc..123H Altcode: 1992ecos....1..123H A cylindrical fabric-soil structural concept for implementation on the moon and Mars which provides many advantages is proposed. The most efficient use of fabric is to fashion it into cylindrical tubes, creating cylindrical fabric-confined soil structures. The length, diameter, and curvature of the tubes will depend on the intended application. The cylindrical hoop forces provide radial confinement while end caps provide axial confinement. One of the ends is designed to allow passage of the soil into the fabric tube before sealing. Transportation requirements are reduced due to the low mass and volume of the fabric. Construction requirements are reduced due to the self-erection capability via the pneumatic exoskeleton. Maintenance requirements are reduced due to the passive nature of the concept. The structure's natural ductility is well suited for any seismic activity. Title: Coronal Mass Ejection Authors: Harrison, Richard A. Bibcode: 1991RSPTA.336..401H Altcode: We summarize the observational aspects of the transient solar coronal features known as coronal mass ejections. Recognizing the importance of understanding this form of solar activity, particularly in the light of relations to flare and prominence activity, and geomagnetic effects, we consider the spectrum of models which have been used to describe these events and assess their viability. We find most models to be unphysical and all represent a gross over simplification of solar conditions. In conclusion we set up a cartoon model which best fits the observations and which we feel should be further developed. Title: Book Review: Dynamics of quiescent prominences / Springer, 1991 Authors: Harrison, R. A. Bibcode: 1991Obs...111..198H Altcode: No abstract at ADS Title: Solar plasma energisation: basic concepts. Authors: Harrison, Richard A. Bibcode: 1991AnGeo...9..170H Altcode: 1991AnG.....9..170H The author describes the basic properties of the solar atmosphere and outlines the mechanisms which may operate to produce the solar wind, to heat the corona and to drive the transient events which we observe, such as flares and coronal mass ejections. The aim of this review is to provide a useful perspective for the solar physicist as well as an introduction for those not familiar with the Sun. Title: European Geophysical Society, Symposium on Acceleration and Heating Processes in Solar System Plasmas, Copenhagen, Denmark, Apr. 23-27, 1990, Proceedings Authors: Harrison, Richard A.; Saunders, Mark Bibcode: 1991AnGeo...9.....H Altcode: The present symposium on acceleration and heating processes in solar system plasmas discusses magnetic reconnection (solar flares, coronal mass ejections, coronal heating, the earth's dayside magnetopause, and substorms). Attention is given to shocks (coronal mass ejections, interplanetary and planetary shocks), parallel electric fields (auroral acceleration), and wave heating (wave particle interactions). Topics addressed include cometary plasma energization, acceleration and heating of space plasmas, wave activity in the solar atmosphere, the solar wind mass flux problem, and auroral energization processes. Title: Book Review: Solar astrophysics / Wiley Interscience, 1990 Authors: Harrison, R. A. Bibcode: 1991Obs...111...45H Altcode: 1991Obs...111...45F No abstract at ADS Title: The Detection of Wave Activity in the Solar Corona Using Ultraviolet Spectra Authors: McClements, K. G.; Harrison, R. A.; Alexander, D. Bibcode: 1991SoPh..131...41M Altcode: The SUMER and CDS instruments on the Solar and Heliopheric Observatory spacecraft (SOHO), due to be launched in 1995, may enable us to identify the dominant mechanism responsible for solar coronal heating. In this paper we examine, in particular, the possibility that Alfvén or acoustic waves, propagating through the corona and heating the ambient plasma, could be detected through the measurement of ultra-violet line widths. The contribution of wave broadening to the total line width depends on the orientation of the magnetic field with respect to the line of sight. CDS may be used to identify the magnetic field geometry in a particular region. The spatial resolution provided by SUMER, superior to that of previous instruments, should then make it possible to discriminate between different broadening mechanisms. In the case of lines produced by heavy ions in the low corona, we find that the line width produced by an Alfvén wave flux sufficiently high to heat the active corona corresponds to a Doppler temperature of up to twenty times the kinetic temperature. Title: Coronal transients and their relation to solar flares Authors: Harrison, R. A. Bibcode: 1991AdSpR..11a..25H Altcode: 1991AdSpR..11...25H Our understanding of the relationship between coronal transient events and flare activity is severely restricted by a complex web of preconception, mythology and misinterpretation. In principle, for some time we have had access to the observations needed to develop a good knowledge of coronal activity at the time of flaring. However, this has required the combination of rather incompatible data-sets - a stumbling block for many. In this paper, we attempt to clear some of the dead-wood and simply ask the question: what happens in the low corona at about the time of a coronal mass ejection? There is no attempt to provide a thorough review of the literature; we simply re-examine several large data-sets and draw conclusions. We supplement this analysis with comments on related phenomena which have been the target of some controversy, e.g long duration X-ray events, flare precursors and X-ray arches, in an effort to gain a better perspective. Title: Preface Authors: Harrison, R. A. Bibcode: 1991CIBu..121....1H Altcode: No abstract at ADS Title: Coronal mass ejection. Authors: Harrison, R. A. Bibcode: 1991psf..conf..401H Altcode: The author summarizes the observational aspects of the transient solar coronal features known as coronal mass ejections. Recognizing the importance of understanding this form of solar activity, particularly in the light of relations to flare and prominence activity, and geomagnetic effects, he considers the spectrum of models which have been used to describe these events and assess their viability. The author finds most models to be unphysical and all represent a gross over simplification of solar conditions. In conclusion he sets up a cartoon model which best fits the observations and which should be further developed. Title: Pamela Rothwell Martelli 1926-1991 Authors: Harrison, R. Bibcode: 1991CIBu..121....6H Altcode: No abstract at ADS Title: The surge events of June 28 and October 30, 1980 Authors: Harrison, R. A.; Sime, D. G.; Pearce, G. Bibcode: 1990A&A...238..347H Altcode: Similarities between two surge events, observed using the High Altitude Observatory's Prominence Monitor on Mauna Loa, Hawaii and the Hard X-ray Imaging Spectrometer on NASA's Solar Maximum Mission, are discussed. In both events, a soft X-ray burst occurs adjacent to a large quiescent prominence structure. After the onset of the burst, a surge occurs in loop structures adjacent to the burst side and on the side remote from the prominence. It is observed that, even though the surge is removed physically from the burst side, it appears to be related to the burst activity. It is suggested that the burst activity and H-alpha ejecta are different manifestations of a single event involving a large-scale structure. These results are not consistent with those obtained using previous models of such events. Title: Fine-scale structure on the Sun Authors: Harrison, R. A. Bibcode: 1990Obs...110...84H Altcode: No abstract at ADS Title: The coronal diagnostic spectrometer - a solar EUV experiment for the SOHO mission. Authors: Patchett, B. E.; Harrison, R. A.; Sawyer, E. C. Bibcode: 1990JBIS...43..181P Altcode: The scientific background of the Solar and Heliospheric Observatory (SOHO) mission, a joint operation of NASA and ESA planned for 1995, is given, and the main goals of the mission are defined. Two out of three fundamental problems addressed, such as the existence and heating of the solar corona, and causes and locations of the solar-wind stream acceleration, will be examined by the major SOHO instrument, the coronal diagnostic spectrometer (CDS). The CDS is designed to obtain the intensity ratios of selected diagnostic line-pairs in the EUV, at spatial and temporal resolutions appropriate to the fine scale features of the solar atmosphere. Its design is a hybrid instrument, with an astigmatic grazing incidence spectrometer to access the important coronal line below 300 A and a stigmatic normal incidence spectrometer to view the lines larger than 300 A. Title: The Source Regions of Solar Coronal Mass Ejections Authors: Harrison, Richard A. Bibcode: 1990SoPh..126..185H Altcode: Knowledge of the origin of the solar coronal mass ejection (CME) may be crucial to our understanding of several active solar phenomena, such as flares, as well as to the structure and stability of the corona and the prediction of interplanetary disturbances. In recent years, two camps of opinion have emerged, based on the belief that CMEs either commonly originate from structures intimately linked to active regions or they originate from coronal hole regions. This present study investigates the locations of 95 CME events observed during 1984-1986 relative to coronal hole and active region features. We find no evidence to support the coronal hole hypothesis and many indications that active regions are indeed associated with the source regions of CMEs. Title: Sympathetic flaring Authors: Pearce, G.; Harrison, R. A. Bibcode: 1990A&A...228..513P Altcode: An examination of the relationship between the flaring of 15 active region pairs and their physical separations is found to support the existence of sympathetic flare activity on the sun. In general, active region pairs separated by less than 35 heliographic degrees show a significant departure from random coincident flare activity. These regions represent one extreme of a spectrum which suggests that there is an inverse correlation between the pair separation and the degree of coincident flare activity. Title: The launch of solar coronal mass ejections: Results from the coronal mass ejection onset program Authors: Harrison, R. A.; Hildner, E.; Hundhausen, A. J.; Sime, D. G.; Simnett, G. M. Bibcode: 1990JGR....95..917H Altcode: We describe a set of solar coronal mass ejection (CME) events where coincident data sets from both X ray and white light instruments have been made available through deliberate planning. Using these we have been able to put tight limits on possible descriptions of the typical sequence of events, and these we relate to interpretations of models involving flares and CMEs. Our findings confirm recent suggestions that CME onsets precede any related flare activity and that the associated flaring commonly lies to one side of the CME span. The CME launch appears to be associated with minor X ray (flare precursor) activity. Although this scenario has been previously discussed (see Harrison, 1986, and references therein), the abundance of flare and CME models which are not compatible with this picture demands that confirmation be sought using programs such as this. Title: Book Review: The physics of solar flares. / CUP, 1988 Authors: Harrison, R. Bibcode: 1989Obs...109..107H Altcode: 1989Obs...109..107T No abstract at ADS Title: The launch of coronal mass ejections: White light and x ray observations in the low corona Authors: Harrison, R. A.; Sime, D. G. Bibcode: 1989JGR....94.2333H Altcode: As part of an ongoing program to determine the processes which lead to the launch of solar coronal mass ejections (CMEs) we present a thorough examination of periods where there are observations from the hard X ray imaging spectrometer on the Solar Maximum Mission which are complementary to observations made by the MkIII K-coronameter on Hawaii. At the time of the observations no attempt was made to produce compatible data sets so the analysis is hampered by unfortunate timing and pointing. Nevertheless, with the analysis of six events we are able to draw some useful conclusions which agree with the findings of our previous work but dispute the scenarios presented by most theoretical models of the CME launch and the CME/flare relationship. To summarize briefly our results: (1) None of the CME launches occur in coincidence with a flare onset, (2) flares which do occur in the vicinity of a CME launch site occur both after the CME onset and in one foot of the CME structure, (3) there is weak X ray activity also associated with the footpoints of the CME structures and these indicate the presence of large coronal structures which underlie the CME structures, (4) there are X ray enhancements after all of the CME onsets; in some cases these are bright enough to be classed as flares, and in others they are lesser brightenings which we refer to as subflares. Title: A statistical analysis of the soft X-ray profiles of solar flares. Authors: Pearce, G.; Harrison, R. A. Bibcode: 1989sasf.confP.161P Altcode: 1989IAUCo.104P.161P; 1988sasf.conf..161P The authors undertake a statistical analysis of the soft X-ray (3.5 - 5.5 keV) profiles of solar flares as observed with the Hard X-ray Imaging Spectrometer on the SMM. The durations, maximum intensities and intensity profiles of the flares are examined. The properties of the "typical" solar flare are discussed. Title: Comments on coronal mass ejection onset studies Authors: Harrison, R. A.; Sime, D. G. Bibcode: 1989A&A...208..274H Altcode: The relationship between solar Coronal Mass Ejections (CMEs) and other solar activity, such as flares and prominences, is not yet clear. Recent analyses have highlighted the complexity of the initial stages of the CME, and this has demanded a reexamination of past studies where clear relationships were claimed. A number of studies are shown where preconceived ideas have damaged the interpretation of the data. The message is one of caution, for both reader and researcher, to recognize bias in CME analyses. Title: Coronal mass ejections and coronal structures. Authors: Hildner, E.; Bassi, J.; Bougeret, J. L.; Duncan, R. A.; Gary, D. E.; Gergely, T. E.; Harrison, R. A.; Howard, R. A.; Illing, R. M. E.; Jackson, B. V.; Kahler, S. W.; Kopp, K.; Low, B. C.; Lantos, P.; Phillips, K. J. H.; Poletto, G.; Sheeley, N. R., Jr.; Stewart, R. T.; Svestka, Z.; Waggett, P. W.; Wu, S. T. Bibcode: 1989epos.conf..493H Altcode: The work of this team was concerned with modelling of post-flare arches, the reconnection theory of flares, the slow variation of coronal structure, and the coronal and interplanetary detection, evolution, and consequences of mass ejections. Title: Preflare activity. Authors: Priest, E. R.; Gaizauskas, V.; Hagyard, M. J.; Schmahl, E. J.; Webb, D. F.; Cargill, P.; Forbes, T. G.; Hood, A. W.; Steinolfson, R. S.; Chapman, G. A.; Deloach, A. C.; Gary, G. A.; Jones, H. P.; Karpen, J. T.; Martres, M. -J.; Porter, J. G.; Schmieder, B.; Smith, J. B., Jr.; Toomre, J.; Woodgate, B.; Waggett, P.; Bentley, R.; Hurford, G.; Schadee, A.; Schrijver, J.; Harrison, R.; Martens, P. Bibcode: 1989epos.conf....1P Altcode: Contents: 1. Introduction. 2. Magnetohydrodynamic instability. 3. Preflare magnetic and velocity fields. 4. Coronal manifestations of preflare activity. Title: Largescale Magnetic Field Phenomena Authors: Harrison, R. A.; Bentley, R. D.; Brosius, J.; Dwivedi, B. N.; Jardine, M.; Klimchuk, J. A.; Kundu, M. R.; Pearce, G.; Saba, J.; Sakurai, T.; Schmahl, E. J.; Schmelz, J.; Sime, D. G.; Steele, C. D. C.; Sun, M. T.; Tappin, S. J.; Waljeski, K.; Wang, A. H.; Wu, S. T. Bibcode: 1989tnti.conf....1H Altcode: No abstract at ADS Title: The solar-stellar connection: the relationship between flaring rates, flare power and quiescent X-ray background. Authors: Harrison, R. A.; Pearce, G.; Skumanich, A. Bibcode: 1989sasf.confP..13H Altcode: 1988sasf.conf...13H; 1989IAUCo.104P..13H The aim of this study is to extend the dMe analysis to the sun, to explore relationships between the flaring-rate, flare power-loss and quiescent X-ray luminosity for different solar active regions. Title: CDS: The Coronal Diagnostic Spectrometer Authors: Patchett, B. E.; Harrison, R. A.; Sawyer, E. C.; Aschenbach, B.; Culhane, J. L.; Doschek, G. A.; Gabriel, A. H.; Huber, M. C. E.; Jordan, C.; Kjeldseth-Moe, O. Bibcode: 1988sohi.rept...39P Altcode: The prime objective of the Coronal Diagnostic Spectrometer (CDS) is to obtain intensity ratios of selected extreme-ultraviolet line pairs, with spatial and temporal scales appropriate to the fine-scale features of the solar atmosphere. This will be done simultaneously across a large portion of the solar atmosphere. From this, density and temperature information will be derived which coupled with a modest capability for the detection of flows will be used to study the energy and mass balance of the atmosphere. Understanding the heating of the solar corona and the acceleration of the solar wind are the ultimate goals of this research. Title: A statistical analysis of the soft X-ray profiles of solar flares Authors: Pearce, G.; Harrison, R. A. Bibcode: 1988A&A...206..121P Altcode: The authors undertake a statistical analysis of the soft X-ray (3.5 - 5.5 keV) profiles of solar flares as observed with the Hard X-ray Imaging Spectrometer on the Solar Maximum Mission. Data are presented for 59 flares. The durations, maximum intensities and intensity profiles of the flares are examined. The properties of the "typical" solar flare are discussed. The distributions of the measured parameters with respect to one another reveal some interesting results. In common with past studies, it is concluded that there is no evidence to suggest that more than one type of event is being viewed, despite a desire evident in the literature to place events into distinct groups. It is also concluded that commonly held views about the relationships between flare duration and intensity, profile asymmetries and intensity etc., are in error. Title: Active Region Coronal Loops: Structure and Variability Authors: Haisch, Bernhard M.; Strong, Keith T.; Harrison, Richard A.; Gary, G. A. Bibcode: 1988ApJS...68..371H Altcode: X-ray images of a pair of active region loops are studied which show significant, short time-scale variability in the line fluxes of O VIII, Ne IX, and Mg XI and in the 3.5-11.5 keV soft X-ray bands. Vector magnetograms and high-resolution UV images were used to model the three-dimensional characteristics of the loops. X-ray light curves were generated spanning four consecutive orbits for both loops individually, and light curves of the loop tops and brightest points were also generated. The largest variations involve flux changes of up to several hundred percent on time scales of 10 minutes. No significant H-alpha flare activity is reported, and loop temperatures remain in the four to six million K range. The decay phases of the light curves indicate radiative cooling, inhibition of conduction, and some type of 'continued heating' due to ongoing, underlying activity at the microflare level. Title: The Solar-Stellar Connection: The Relationship between Flaring Rates, Flare Power, and Quiescent X-Ray Background Authors: Harrison, Richard A.; Pearce, Gillian; Skumanich, Andrew Bibcode: 1988ApJ...332.1058H Altcode: The flaring rates, flare powers, and quiescent X-ray luminosities of dMe (red dwarf) stars are compared with those of solar active regions. In dMe stars, these properties are found to be closely related, and this may have a significant influence on the understanding of the flare process and coronal heating. For example, a correlation between flare rate and quiescent X-ray luminosity suggests that both may be driven by similar processes on a differing scale. It is a natural extension of this work to investigate similar relationships for the sun. The results are mixed. The relationships between the various parameters are certainly not as clear for the sun as for the dMe stars. Some solar properties appear to vary in a manner similar to the dMe analysis, and some contradict the dMe case. The implications of this are discussed. Title: X-ray emission associated with solar prominences, sprays and surges Authors: Harrison, R. A.; Rompolt, B.; Garczynska, I. Bibcode: 1988SoPh..116...61H Altcode: Using Hα observations made at the Astronomical Observatory of Wroclaw University, and 3.5-5.5 keV X-ray data from the Hard X-ray Imaging Spectrometer on board the Solar Maximum Mission, sites of solar X-ray emission are identified which are associated with active Hα features, such as prominences, sprays and surges. The X-ray emission is found to be highly localized within the active (Hα) structures. For example, in the prominences examined, 3.5-5.5 keV X-rays were found only in compact sites near the feet of the prominences. Models predicting that, during the active phase of these structures, the energy release should be evenly distributed along the structure are clearly brought into question. It is argued that these X-ray sites are indicative of the cause of the expulsion and transport of chromospheric material. Models which satisfy these observations are discussed. Title: A glimpse at the complexity and role of solar coronal mass ejections, through the analysis of one event. Authors: Harrison, R. A. Bibcode: 1988hmas.conf...81H Altcode: The Mk III K-Coronameter on Mauna Loa (Hawaii) operates with a fundamentally different approach to the traditional coronagraph and has been able to observe coronal mass ejections (CMEs) down to ≡0.2 Rsun above the solar limb. A recent inspection of the Mk III K-Coronameter data revealed a particularly well viewed event on August 8, 1980. The author describes this event in detail, as a way of illustrating the complexity of the CME problem and to highlight the role of the CME in solar activity. Title: Solar soft X-ray pulsations Authors: Harrison, R. A. Bibcode: 1987A&A...182..337H Altcode: Using data from the Hard X-ray Imaging Spectrometer on the Solar Maximum Mission, soft X-ray (3.5 - 5.5 keV) pulsations are identified, which originate from a compact active region which lies at one footpoint of a large coronal loop. It is believed that this is the first report of soft X-ray pulsations from the non-flaring sun. The pulsations were of period 24 min and were detected for six hours. The periodicity is thought to be produced by a standing wave or a travelling wave "packet" which exists within the loop. The candidates for the wave are fast or Alfvén MHD modes of Alfvénic surface waves. Title: Interplanetary Effects of Coronal Mass Ejections Authors: Hildner, E.; Bassi, J.; Bougeret, J. L.; Duncan, R. A.; Gary, D. E.; Gergely, T. E.; Harrison, R. A.; Howard, R. A.; Illing, R. M. E.; Jackson, B. V.; Kahler, S. W.; Kopp, K.; Low, B. C.; Lantos, P.; Phillips, K. J. H.; Poletto, G.; Sheeley, N. R., Jr.; Steward, R. T.; Svestka, Z.; Waggett, P. W.; Wu, S. T. Bibcode: 1986epos.conf.6.52H Altcode: 1986epos.confF..52H No abstract at ADS Title: Initiations of Coronal Mass Ejections Authors: Hildner, E.; Bassi, J.; Bougeret, J. L.; Duncan, R. A.; Gary, D. E.; Gergely, T. E.; Harrison, R. A.; Howard, R. A.; Illing, R. M. E.; Jackson, B. V.; Kahler, S. W.; Kopp, K.; Low, B. C.; Lantos, P.; Phillips, K. J. H.; Poletto, G.; Sheeley, N. R., Jr.; Steward, R. T.; Svestka, Z.; Waggett, P. W.; Wu, S. T. Bibcode: 1986epos.conf.6.27H Altcode: 1986epos.confF..27H No abstract at ADS Title: Coronal manifestations of preflare activity Authors: Schmahl, E. J.; Webb, D. F.; Woodgate, B.; Waggett, P.; Bentley, R.; Hurford, G.; Schadee, A.; Schrijver, J.; Harrison, R.; Martens, P. Bibcode: 1986epos.conf.1.48S Altcode: 1986epos.confA..48S A variety of coronal manifestations of precursors or preheating for flares are discussed. Researchers found that almost everyone with a telescope sees something before flares. Whether an all-encompassing scenario will ever be developed is not at all clear at present. The clearest example of preflare activity appears to be activated filaments and their manifestations, which presumably are signatures of a changing magnetic field. But researchers have seen two similar eruptions, one without any evidence of emerging flux (Kundu et al., 1985) and the other with colliding poles (Simon et al., 1984). While the reconnection of flux is generally agreed to be required to energize a flare, the emergence of flux from below (at least on short timescales and in compact regions) does not appear to be a necessary condition. In some cases the cancelling of magnetic flux (Martin, 1984) by horizontal motions instead may provide the trigger (Priest, 1985) Researchers found similarities and some differences between these and previous observations. The similarities, besides the frequent involvement of filaments, include compact, multiple precursors which can occur both at and near (not at) the flare site, and the association between coronal sources and activity lower in the atmosphere (i.e., transition zone and chromosphere). Title: The Slowly Varying Corona Near Solar Activity Maximum Authors: Hildner, E.; Bassi, J.; Bougeret, J. L.; Duncan, R. A.; Gary, D. E.; Gergely, T. E.; Harrison, R. A.; Howard, R. A.; Illing, R. M. E.; Jackson, B. V.; Kahler, S. W.; Kopp, K.; Low, B. C.; Lantos, P.; Phillips, K. J. H.; Poletto, G.; Sheeley, N. R., Jr.; Steward, R. T.; Svestka, Z.; Waggett, P. W.; Wu, S. T. Bibcode: 1986epos.conf.6.57H Altcode: 1986epos.confF..57H No abstract at ADS Title: Modelling of Coronal Mass Ejections and POST Flare Arches Authors: Hildner, E.; Bassi, J.; Bougeret, J. L.; Duncan, R. A.; Gary, D. E.; Gergely, T. E.; Harrison, R. A.; Howard, R. A.; Illing, R. M. E.; Jackson, B. V.; Kahler, S. W.; Kopp, K.; Low, B. C.; Lantos, P.; Phillips, K. J. H.; Poletto, G.; Sheeley, N. R., Jr.; Steward, R. T.; Svestka, Z.; Waggett, P. W.; Wu, S. T. Bibcode: 1986epos.conf6.366H Altcode: 1986epos.confF.366H No abstract at ADS Title: Coronal mass ejections and coronal structures Authors: Hildner, E.; Bassi, J.; Bougeret, J. L.; Duncan, R. A.; Gary, D. E.; Gergely, T. E.; Harrison, R. A.; Howard, R. A.; Illing, R. M. E.; Jackson, B. V. Bibcode: 1986epos.conf..6.1H Altcode: 1986epos.confF...1H Research on coronal mass ejections (CMF) took a variety of forms, both observational and theoretical. On the observational side there were: case studies of individual events, in which it was attempted to provide the most complete descriptions possible, using correlative observations in diverse wavelengths; statistical studies of the properties CMEs and their associated activity; observations which may tell us about the initiation of mass ejections; interplanetary observations of associated shocks and energetic particles even observations of CMEs traversing interplanetary space; and the beautiful synoptic charts which show to what degree mass ejections affect the background corona and how rapidly (if at all) the corona recovers its pre-disturbance form. These efforts are described in capsule form with an emphasis on presenting pictures, graphs, and tables so that the reader can form a personal appreciation of the work and its results. Title: Spectral Line Profiles of Fe XXI 1354.1 Angstrom from the Solar Maximum Mission Authors: Mason, H. E.; Shine, R. A.; Gurman, J. B.; Harrison, R. A. Bibcode: 1986ApJ...309..435M Altcode: Observations of the Fe XXI 1354.1 A line were obtained for several flares using the SMM-UVSP instrument with varying spectral and spatial resolution. Of special interest are spectral line profiles from the footpoints of flare loops taken during the impulsive phase. These data show blueshifted Fe XXI profiles coincident and cospatial with the impulsive brightening of chromospheric material. The present analysis supports the hypothesis that the blueshifted component of the high temperature emission is an integral part of the flare, possibly associated with chromospheric evaporation. Title: Solar coronal mass ejections and flares Authors: Harrison, R. A. Bibcode: 1986A&A...162..283H Altcode: Recent work has indicated that a solar coronal mass ejection begins to rise during a weak, soft X-ray burst which often precedes a flare by several tens of minutes. Using data from the Coronagraph/Polarimeter and the Hard X-ray Imaging Spectrometer, both on board the Solar Maximum Mission, it is shown that the burst originates from a coronal arch which has a very close spatial relationship to the loop-like features of the coronal mass ejection. The data suggest, in fact, that the ejection arises directly from a destabilization or lack of equilibrium reached by the arch. For the three examples discussed, with both X-ray and coronagraph observations, a subsequent flare occurs in one foot of the arch indicating a flare-ejection asymmetry. This asymmetry is common in examples of flare associated coronal mass ejections that can be found in the literature. The data suggest a picture which is inconsistent with most models of the mass ejection phenomenon. Title: Preflare activity. Authors: Priest, E. R.; Gaizauskas, V.; Hagyard, M. J.; Schmahl, E. J.; Webb, D. F.; Cargill, P.; Forbes, T. G.; Hood, A. W.; Steinolfson, R. S.; Chapman, G. A.; Deloach, A. C.; Gary, G. A.; Jones, H. P.; Karpen, J. T.; Martres, M. -J.; Porter, J. G.; Schmieder, B.; Smith, J. B., Jr.; Toomre, J.; Woodgate, B.; Waggett, P.; Bentley, R.; Hurford, G.; Schadee, A.; Schrijver, J.; Harrison, R.; Martens, P. Bibcode: 1986NASCP2439....1P Altcode: Contents: 1. Introduction: the preflare state - a review of previous results. 2. Magnetohydrodynamic instability: magnetic reconnection, nonlinear tearing, nonlinear reconnection experiments, emerging flux and moving satellite sunspots, main phase reconnection in two-ribbon flares, magnetic instability responsible for filament eruption in two-ribbon flares. 3. Preflare magnetic and velocity fields: general morphology of the preflare magnetic field, magnetic field shear, electric currents in the preflare active region, characterization of the preflare velocity field, emerging flux. 4. Coronal manifestations of preflare activity: defining the preflare regime, specific illustrative events, comparison of preflare X-rays and ultraviolet, preflare microwave intensity and polarization changes, non-thermal precursors, precursors of coronal mass ejections, short-lived and long-lived HXIS sources as possible precursors. Title: Coronal mass ejections and coronal structures. Authors: Hildner, E.; Bassi, J.; Bougeret, J. L.; Duncan, R. A.; Gary, D. E.; Gergely, T. E.; Harrison, R. A.; Howard, R. A.; Illing, R. M. E.; Jackson, B. V.; Kahler, S. W.; Kopp, K.; Low, B. C.; Lantos, P.; Phillips, K. J. H.; Poletto, G.; Sheeley, N. R., Jr.; Stewart, R. T.; Svestka, Z.; Waggett, P. W.; Wu, S. T. Bibcode: 1986NASCP2439....6H Altcode: Contents: 1. Introduction. 2. Observations. 3. Initiation of coronal mass ejections - observations. 4. Modelling of coronal mass ejections and post-flare arches. 5. Interplanetary effects of coronal mass ejections. 6. The slowly varying corona near solar activity maximum. 7. Summary. Title: The Onset of Coronal Mass Ejections Authors: Simnett, G. M.; Harrison, R. A. Bibcode: 1985SoPh...99..291S Altcode: This study addresses the onset of coronal mass ejections. From examination of sensitive X-ray images from the Solar Maximum Mission around the projected onset time of coronal mass ejections we identify two important new features: (1) there is usually a weak, soft X-ray enhancement 15-30 min prior to the linearly extrapolated chromospheric departure time of the ejection; (2) this activity is generally from two widely separated (≥ 105 km) parts of the Sun. Possible physical mechanisms for these phenomena are examined and it is concluded that a plausible explanation is that the initial energy release is converted first into kinetic energy of suprathermal protons, 102-103 keV. The protons are trapped in a large magnetic loop which later breaks open as the mass ejection; Coulomb losses are the destabilizing agent but the mass ejection is probably magnetically driven. Protons that escape into the loss cone will impact the loop footpoints to heat the upper chromospheric material to a sufficiently high temperature to generate the weak soft X-ray emission. There will also be an Hα signature, and this is observed in a number of events. There is in general no radio emission or hard X-ray emission accompanying the soft X-ray precursor. When the coronal mass ejection is followed by a flare, then this is generally from a point close to, but not identical to, one of the points with the earlier soft X-ray enhancement. Title: The X-Ray Signature of Solar Coronal Mass Ejections Authors: Harrison, R. A.; Waggett, P. W.; Bentley, R. D.; Phillips, K. J. H.; Bruner, M.; Dryer, M.; Simnett, G. M. Bibcode: 1985SoPh...97..387H Altcode: The coronal response to six solar X-ray flares has been investigated. At a time coincident with the projected onset of the white-light coronal mass ejection associated with each flare, there is a small, discrete soft X-ray enhancement. These enhancements (precursors) precede by typically ∼20 m the impulsive phase of the solar flare which is dominant by the time the coronal mass ejection has reached an altitude above 0.5 R. We identify motions of hot X-ray emitting plasma, during the precursors, which may well be a signature of the mass ejection onsets. Further investigations have also revealed a second class of X-ray coronal transient, during the main phase of the flare. These appear to be associated with magnetic reconnection above post-flare loop systems. Title: White Light and X-ray Studies of the Coronal Mass Ejection Onset Phase Authors: Harrison, R. A. Bibcode: 1985BAAS...17..636H Altcode: No abstract at ADS Title: The X-ray signature of solar coronal mass ejections. Authors: Harrison, R. A.; Waggett, P. W.; Bentley, R. D.; Phillips, K. J. H.; Bruner, M.; Dryer, M.; Simnett, G. M. Bibcode: 1985RALR...84.....H Altcode: The coronal response to six solar X-ray flares has been investigated. At a time coincident with the projected onset of the white-light coronal mass ejection with each flare, there is a small, discrete soft X-ray enhancement. These enhancements (precursors) precede by typically ≡20 m the impulsive phase of the solar flare which is dominant by the time the coronal mass ejection has reached an altitude above 0.5 R_sun;. The authors identify motions of hot X-ray emitting plasma, during the precursors, which may well be a signature of the mass ejection onsets. Further investigations have also revealed a second class of X-ray coronal transients, during the main phase of the flare. These appear to be associated with magnetic reconnection above post-flare loop systems. Title: A study of the morphology of solar flares as observed by the hard X-ray imaging spectrometer. Authors: Harrison, R. A.; Simnett, G. M. Bibcode: 1984ESASP.220..281H Altcode: 1984ESPM....4..281H The authors have conducted an analysis of solar flares in the 3.5 - 30 keV energy region. They show that the majority of flares appear to conform to the following scenario: in 3.5 - 30 keV X-rays, the impulsive burst defines a system of low lying coronal magnetic loops. The soft X-ray (<10 keV) flare subsequently expands into a larger, well resolved loop system and frequently an even larger overlying structure is involved with footpoints separated by several hundred thousand km. Title: Do all flares occur within a hierarchy of magnetic loops? Authors: Harrison, R. A.; Simnett, G. M. Bibcode: 1984AdSpR...4g.199H Altcode: 1984AdSpR...4..199H X-ray events observed by the Hard X-ray Imaging Spectrometer on the Solar Maximum Mission frequently indicate the following scenario for solar flares: The initial energy release occurs in a compact magnetic loop and during the impulsive phase may spread rapidly to involve a larger structure. In later phases the soft X-ray emission is from a much larger structure encompassing these initial features and, overlying them all is a huge loop with footpoints separated by up to several hundred thousand km. In the light of these observations, we believe a flare model involving a single magnetic loop is rarely, if ever appropriate. Title: Hard X-Ray Studies of the Large Coronal Feature on June 29, 1980 Authors: Harrison, R. A.; Simnett, G. M.; Hoyng, P.; Lafleur, H.; van Beek, H. F. Bibcode: 1984sii..conf..287H Altcode: No abstract at ADS Title: Advanced regenerative environmental control and life support systems: Air and water regeneration Authors: Simnett, G. M.; Harrison, R. A. Bibcode: 1984AdSpR...4g.279S Altcode: 1984AdSpR...4..279S Extended manned space missions will require regenerative life support techniques. Past U.S. manned missions used nonregenerative expendables, except for a molecular sieve-based carbon dioxide removal system aboard Skylab. The resupply penalties associated with expendables becomes prohibitive as crew size and mission duration increase. The U.S. Space Station, scheduled to be operational in the 1990's, is based on a crew of four to sixteen and a resupply period of 90 days or greater. It will be the first major spacecraft to employ regenerable techniques for life support. The paper uses the requirements for the Space Station to address these techniques. Title: Evidence for Extensive Magnetic Structures Between Two Active Regions from Studies of Flares on June 24, 1980 Authors: Simnett, G. M.; Harrison, R. A.; Hoyng, P.; van Beek, H. F. Bibcode: 1984sii..conf..273S Altcode: No abstract at ADS Title: The structure and evolution of a solar flare as observed in 3.5 30 keV X-rays Authors: Harrison, R. A.; Simnett, G. M.; Hoyng, P.; Lafleur, H.; van Beek, H. F. Bibcode: 1983SoPh...84..237H Altcode: On July 5, 1980 the Hard X-Ray Imaging Spectrometer on board the Solar Maximum Mission observed a complex flare event starting at 22 : 32 UT from AR 2559 (Hale 16955), then at N 28 W 29, which developed finally into a 2-ribbon flare. In this paper we compare the X-ray images with Hα photographs taken at the Big Bear Solar Observatory and identify the site of the most energetic flare phenomena. During the early phases of the event the hard X-rays (>16 keV) came from a compact source located near one of the two bright Hα kernels; we believe the latter are at the footpoints of a compact magnetic loop. The kernel identified with the X-ray source is immediately adjacent to one of the principal sunspots and in fact appears to `rotate' around the sunspot over 90° in the early phase of the flare. Two intense X-ray bursts occur at the site of the rotating kernel, and following each burst the loop fills with hot, X-ray emitting plasma. If the first burst is interpreted as bremsstrahlung from a beam of electrons impinging on a collisionally dominated medium, the energy in such electrons, >16 keV, is ∼ 5 × 1030 erg. The altitude of the looptop is 7-10 × 103 km. The temperature structure of the flare is extremely non-homogeneous, and the highest temperatures are found in the top of the loop. Title: Multifarious Spatial Structure in a Compact Hard X-Ray Flare Authors: Harrison, R. A.; Vanbeek, H. F.; Hoyng, P.; Lafleur, H.; Simnett, G. M. Bibcode: 1980BAAS...12..911H Altcode: No abstract at ADS Title: A Study of the Impulsive Flares and Homologous Flares From AR2372 From April 6-13, Using Hard X-Ray Images Authors: Simnett, G. M.; Machado, M.; Harrison, R. A.; Hoyng, P.; Lafleur, H.; Svestka, Z.; Vanbeek, H. F. Bibcode: 1980BAAS...12S.899S Altcode: No abstract at ADS