Author name code: bettonvil ADS astronomy entries on 2022-09-14 author:"Bettonvil, Felix C.M." ------------------------------------------------------------------------ Title: Locating dust and molecules in the inner circumstellar environment of R~Sculptoris with MATISSE Authors: Drevon, Julien; Millour, Florentin; Cruzalèbes, Pierre; Paladini, Claudia; Hron, Josef; Meilland, A.; Allouche, F.; Hofmann, K. -H.; Lagarde, S.; Lopez, B.; Matter, A.; Petrov, R.; Robbe-Dubois, S.; Schertl, D.; Wittkowski, M.; Zins, G.; Ábrahám, P.; Antonelli, P.; Beckmann, U.; Berio, P.; Bettonvil, F.; Glindemann, A.; Graser, U.; Heininger, M.; Henning, Thomas; Isbell, Jacob W.; Jaffe, Walter; Labadie, Lucas; Leinert, Christoph; Lehmitz, Michael; Morel, Sébastien; Meisenheimer, Klaus; Soulain, Anthony; Varga, Josef; Weigelt, Gerd; Woillez, Julien; Augereau, Jean-Charles; van Boekel, Roy; Burtscher, Leonard; Danchi, William; Dominik, Carsten; Gamez-Rosas, Violetta; Hocdé, Vincent; Hogerheijde, M.; Klarmann, Lucia; Kokoulina, Elena; Leftley, James; Stee, Ph.; Vakili, Farrokh; Waters, Rens; Wolf, Sebastian; Yoffe, Gideon Bibcode: 2022arXiv220810845D Altcode: AGB stars are one of the main sources of dust production in the Galaxy. However, it is not clear what this process looks like and where the dust is condensing in the circumstellar environment. By characterizing the location of the dust and the molecules in the close environment of an AGB star, we aim to achieve a better understanding the history of the dust formation process. We observed the carbon star R Scl with the VLTI-MATISSE instrument in L- and N-bands. The high angular resolution of the VLTI observations, combined with a large uv-plane coverage allowed us to use image reconstruction methods. To constrain the dust and molecules' location, we used two different methods: MIRA image reconstruction and the 1D code RHAPSODY. We found evidence of C2H2 and HCN molecules between 1 and 3.4 Rstar which is much closer to the star than the location of the dust (between 3.8 and 17.0 Rstar). We also estimated a mass-loss rate of 1.2+-0.4x10-6 Msun per yr. In the meantime, we confirmed the previously published characteristics of a thin dust shell, composed of amorphous carbon (amC) and silicon carbide (SiC). However, no clear SiC feature has been detected in the MATISSE visibilities. This might be caused by molecular absorption that can affect the shape of the SiC band at 11.3 micron. The appearance of the molecular shells is in good agreement with predictions from dynamical atmosphere models. For the first time, we co-located dust and molecules in the environment of an AGB star. We confirm that the molecules are located closer to the star than the dust. The MIRA images unveil the presence of a clumpy environment in the fuzzy emission region beyond 4.0 Rstar. Furthermore, with the available dynamic range and angular resolution, we did not detect the presence of a binary companion. Additional observations combining MATISSE and SAM-VISIR instrument should enable this detection in future studies. Title: The dusty heart of Circinus. I. Imaging the circumnuclear dust in N-band Authors: Isbell, J. W.; Meisenheimer, K.; Pott, J. -U.; Stalevski, M.; Tristram, K. R. W.; Sanchez-Bermudez, J.; Hofmann, K. -H.; Gámez Rosas, V.; Jaffe, W.; Burtscher, L.; Leftley, J.; Petrov, R.; Lopez, B.; Henning, T.; Weigelt, G.; Allouche, F.; Berio, P.; Bettonvil, F.; Cruzalebes, P.; Dominik, C.; Heininger, M.; Hogerheijde, M.; Lagarde, S.; Lehmitz, M.; Matter, A.; Meilland, A.; Millour, F.; Robbe-Dubois, S.; Schertl, D.; van Boekel, R.; Varga, J.; Woillez, J. Bibcode: 2022A&A...663A..35I Altcode: 2022arXiv220501575I Context. Active galactic nuclei play a key role in the evolution of galaxies, but their inner workings and physical connection to the host are poorly understood due to a lack of angular resolution. Infrared interferometry makes it possible to resolve the circumnuclear dust in the nearby Seyfert 2 galaxy, the Circinus Galaxy. Previous observations have revealed complex structures and polar dust emission but interpretation was limited to simple models. The new Multi AperTure mid-Infrared Spectro-Scopic Experiment (MATISSE) makes it possible to image these structures for the first time.
Aims: We aim to precisely map the morphology and temperature of the dust surrounding the supermassive black hole through interferometric imaging.
Methods: We observed the Circinus Galaxy with MATISSE at the Very Large Telescope Interferometer (VLTI), producing 150 correlated flux spectra and 100 closure phase spectra. The novel inclusion of closure phases makes interferometric imaging possible for the first time. We reconstructed images in the N-band at ∼10 mas resolution. We fit blackbody functions with dust extinction to several aperture-extracted fluxes from the images to produce a temperature distribution of central dusty structures.
Results: We find significant substructure in the circumnuclear dust: central unresolved flux of ∼0.5 Jy, a thin disk 1.9 pc in diameter oriented along ∼45°, and a ∼4 × 1.5 pc polar emission extending orthogonal to the disk. The polar emission exhibits patchiness, which we attribute to clumpy dust. Flux enhancements to the east and west of the disk are seen for the first time. We distinguish the temperature profiles of the disk and of the polar emission: the disk shows a steep temperature gradient indicative of denser material; the polar profile is flatter, indicating clumpiness and/or lower dust density. The unresolved flux is fitted with a high temperature, ∼370 K. The polar dust remains warm (∼200 K) out to 1.5 pc from the disk. We attribute approximately 60% of the 12 μm flux to the polar dust, 10% to the disk, and 6% is unresolved; the remaining flux was resolved out. The recovered morphology and temperature distribution resembles modeling of accretion disks with radiation-driven winds at large scales, but we placed new constraints on the subparsec dust.
Conclusions: The spatially resolved subparsec features imaged here place new constraints on the physical modeling of circumnuclear dust in active galaxies; we show strong evidence that the polar emission consists of dust clumps or filaments. The dynamics of the structures and their role in the Unified Model remain to be explored.

This work makes use of ESO Programmes 099.B-0484(A), 0104.B-0064(A), 0104.B-0127(A), 106.214U.002, and 105.205M.001.

The images in Fig. 3 are available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/663/A35 Title: VizieR Online Data Catalog: Circinus galaxy N-band VLTI/MATISSE images (Isbell+, 2022) Authors: Isbell, J. W.; Meisenheimer, K.; Pott, J. -U.; Stalevski, M.; Tristram, K. R. W.; Sanchez-Bermudez, J.; Hofmann, K. -H.; Gamez Rosas, V.; Jaffe, W.; Burtscher, L.; Leftley, J.; Petrov, R.; Lopez, B.; Henning, T.; Weigelt, G.; Allouche, F.; Berio, P.; Bettonvil, F.; Cruzalebes, P.; Dominik, C.; Heininger, M.; Hogerheijde, M.; Lagarde, S.; Lehmitz, M.; Matter, A.; Meilland, A.; Millour, F.; Robbe-Dubois, S.; Schertl, D.; van Boekel, R.; Varga, J.; Woillez, J. Bibcode: 2022yCat..36630035I Altcode: Observations of the active galactic nucleus (AGN), Circinus, with VLTI/MATISSE resulted in the reconstruction of images at seven independent wavelength channels in the N-band. These images show the circumnuclear dust and provide new details on constraints on the structure commonly known as the AGN torus. The images were reconstructed from 150 correlated flux and 100 closure phase measurements obtained in March 2020, February 2021, and June 2021. The images were reconstructed at 8.5, 8.9, 9.7, 10.5, 11.3, 12.0, and 12.7 micrometers. The images are given in Fig. 3 of the paper.

(2 data files). Title: MATISSE, the VLTI mid-infrared imaging spectro-interferometer Authors: Lopez, B.; Lagarde, S.; Petrov, R. G.; Jaffe, W.; Antonelli, P.; Allouche, F.; Berio, P.; Matter, A.; Meilland, A.; Millour, F.; Robbe-Dubois, S.; Henning, Th.; Weigelt, G.; Glindemann, A.; Agocs, T.; Bailet, Ch.; Beckmann, U.; Bettonvil, F.; van Boekel, R.; Bourget, P.; Bresson, Y.; Bristow, P.; Cruzalèbes, P.; Eldswijk, E.; Fanteï Caujolle, Y.; González Herrera, J. C.; Graser, U.; Guajardo, P.; Heininger, M.; Hofmann, K. -H.; Kroes, G.; Laun, W.; Lehmitz, M.; Leinert, C.; Meisenheimer, K.; Morel, S.; Neumann, U.; Paladini, C.; Percheron, I.; Riquelme, M.; Schoeller, M.; Stee, Ph.; Venema, L.; Woillez, J.; Zins, G.; Ábrahám, P.; Abadie, S.; Abuter, R.; Accardo, M.; Adler, T.; Alonso, J.; Augereau, J. -C.; Böhm, A.; Bazin, G.; Beltran, J.; Bensberg, A.; Boland, W.; Brast, R.; Burtscher, L.; Castillo, R.; Chelli, A.; Cid, C.; Clausse, J. -M.; Connot, C.; Conzelmann, R. D.; Danchi, W. -C.; Delbo, M.; Drevon, J.; Dominik, C.; van Duin, A.; Ebert, M.; Eisenhauer, F.; Flament, S.; Frahm, R.; Gámez Rosas, V.; Gabasch, A.; Gallenne, A.; Garces, E.; Girard, P.; Glazenborg, A.; Gonté, F. Y. J.; Guitton, F.; de Haan, M.; Hanenburg, H.; Haubois, X.; Hocdé, V.; Hogerheijde, M.; ter Horst, R.; Hron, J.; Hummel, C. A.; Hubin, N.; Huerta, R.; Idserda, J.; Isbell, J. W.; Ives, D.; Jakob, G.; Jaskó, A.; Jochum, L.; Klarmann, L.; Klein, R.; Kragt, J.; Kuindersma, S.; Kokoulina, E.; Labadie, L.; Lacour, S.; Leftley, J.; Le Poole, R.; Lizon, J. -L.; Lopez, M.; Lykou, F.; Mérand, A.; Marcotto, A.; Mauclert, N.; Maurer, T.; Mehrgan, L. H.; Meisner, J.; Meixner, K.; Mellein, M.; Menut, J. L.; Mohr, L.; Mosoni, L.; Navarro, R.; Nußbaum, E.; Pallanca, L.; Pantin, E.; Pasquini, L.; Phan Duc, T.; Pott, J. -U.; Pozna, E.; Richichi, A.; Ridinger, A.; Rigal, F.; Rivinius, Th.; Roelfsema, R.; Rohloff, R. -R.; Rousseau, S.; Salabert, D.; Schertl, D.; Schuhler, N.; Schuil, M.; Shabun, K.; Soulain, A.; Stephan, C.; Toledo, P.; Tristram, K.; Tromp, N.; Vakili, F.; Varga, J.; Vinther, J.; Waters, L. B. F. M.; Wittkowski, M.; Wolf, S.; Wrhel, F.; Yoffe, G. Bibcode: 2022A&A...659A.192L Altcode: 2021arXiv211015556L Context. Optical interferometry is at a key development stage. The Very Large Telescope Interferometer (VLTI) has established a stable, robust infrastructure for long-baseline interferometry that is usable by general astronomical observers. The present second-generation instruments offer a wide wavelength coverage and improved performance. Their sensitivity and measurement accuracy lead to data and images of high reliability.
Aims: We have developed the Multi AperTure mid-Infrared SpectroScopic Experiment (MATISSE) to access, for the first time, high resolution imaging in a wide spectral domain. Many front-line topics are explored with this new equipment, including: stellar activity and mass loss; planet formation and evolution in the gas and dust disks around young stars; and environment interaction and accretion processes around super massive black holes in active galactic nuclei.
Methods: The instrument is a spectro-interferometric imager in the transmission windows called L, M, and N, from 2.8 to 13.0 microns, combining four optical beams from the VLTI's unit or auxiliary telescopes. Its concept, related observing procedure, data reduction, and calibration approach, is the product of 30 years of instrumental research and has benefitted from the expertise developed in the frame of the VLTI's first generation instruments. The instrument utilises a multi-axial beam combination that delivers spectrally dispersed fringes. The signal provides the following quantities at several spectral resolutions: photometric flux, coherent fluxes, visibilities, closure phases, wavelength differential visibilities and phases, and aperture-synthesis imaging.
Results: This article provides an overview of the physical principle of the instrument and its functionalities. The motivation of the choice of the instrumental concept and the characteristics of the delivered signal are detailed with a description of the observing modes and of their performance limit. MATISSE offers four spectral resolutions in L&M bands, namely 30, 500, 1000 and 3400, and 30 and 220 in the N band, and it provides an angular resolution down to 3 mas for the shortest wavelengths. The MATISSE stand-alone sensitivity limits are 60 mJy in L and 300 mJy in N. The paper gives details of the sensitivity limits for the different measurables and their related precision criteria, considering telescope configurations and spectral resolutions. We also discuss the gain provided with the GRA4MAT fringe tracker. An ensemble of data and reconstructed images illustrate the first acquired key observations.
Conclusions: The instrument has been in operation at Cerro Paranal, ESO, Chile, since 2018, and has been open for science use by the international community since April 2019. The first scientific results are being published now. Title: The extended atmosphere and circumstellar environment of the cool evolved star VX Sagittarii as seen by MATISSE Authors: Chiavassa, A.; Kravchenko, K.; Montargès, M.; Millour, F.; Matter, A.; Freytag, B.; Wittkowski, M.; Hocdé, V.; Cruzalèbes, P.; Allouche, F.; Lopez, B.; Lagarde, S.; Petrov, R. G.; Meilland, A.; Robbe-Dubois, S.; Hofmann, K. -H.; Weigelt, G.; Berio, P.; Bendjoya, P.; Bettonvil, F.; Domiciano de Souza, A.; Heininger, M.; Henning, Th.; Isbell, J. W.; Jaffe, W.; Labadie, L.; Lehmitz, M.; Meisenheimer, K.; Soulain, A.; Varga, J.; Augereau, J. -C.; van Boekel, R.; Burtscher, L.; Danchi, W. C.; Dominik, C.; Drevon, J.; Gámez Rosas, V.; Hogerheijde, M. R.; Hron, J.; Klarmann, L.; Kokoulina, E.; Lagadec, E.; Leftley, J.; Mosoni, L.; Nardetto, N.; Paladini, C.; Pantin, E.; Schertl, D.; Stee, P.; Szabados, L.; Waters, R.; Wolf, S.; Yoffe, G. Bibcode: 2022A&A...658A.185C Altcode: 2021arXiv211210695C Context. VX Sgr is a cool, evolved, and luminous red star whose stellar parameters are difficult to determine, which affects its classification.
Aims: We aim to spatially resolve the photospheric extent as well as the circumstellar environment.
Methods: We used interferometric observations obtained with the MATISSE instrument in the L (3-4 μm), M (4.5-5 μm), and N (8-13 μm) bands. We reconstructed monochromatic images using the MIRA software. We used 3D radiation-hydrodynamics simulations carried out with CO5BOLD and a uniform disc model to estimate the apparent diameter and interpret the stellar surface structures. Moreover, we employed the radiative transfer codes OPTIM3D and RADMC3D to compute the spectral energy distribution for the L, M, and N bands, respectively.
Results: MATISSE observations unveil, for the first time, the morphology of VX Sgr across the L, M, and N bands. The reconstructed images show a complex morphology with brighter areas whose characteristics depend on the wavelength probed. We measured the angular diameter as a function of the wavelength and showed that the photospheric extent in the L and M bands depends on the opacity through the atmosphere. In addition to this, we also concluded that the observed photospheric inhomogeneities can be interpreted as convection-related surface structures. The comparison in the N band yielded a qualitative agreement between the N-band spectrum and simple dust radiative transfer simulations. However, it is not possible to firmly conclude on the interpretation of the current data because of the difficulty in constraing the model parameters using the limited accuracy of our absolute flux calibration.
Conclusions: MATISSE observations and the derived reconstructed images unveil the appearance of VX Sgr's stellar surface and circumstellar environment across a very large spectral domain for the first time.

Based on the observations made with VLTI-ESO Paranal, Chile under the programme IDs 0103.D-0153(D, E, G). The data are available at oidb.jmmc.fr Title: VLTI-MATISSE L- and N-band aperture-synthesis imaging of the unclassified B[e] star FS Canis Majoris Authors: Hofmann, K. -H.; Bensberg, A.; Schertl, D.; Weigelt, G.; Wolf, S.; Meilland, A.; Millour, F.; Waters, L. B. F. M.; Kraus, S.; Ohnaka, K.; Lopez, B.; Petrov, R. G.; Lagarde, S.; Berio, Ph.; Allouche, F.; Robbe-Dubois, S.; Jaffe, W.; Henning, Th.; Paladini, C.; Schöller, M.; Mérand, A.; Glindemann, A.; Beckmann, U.; Heininger, M.; Bettonvil, F.; Zins, G.; Woillez, J.; Bristow, P.; Stee, P.; Vakili, F.; van Boekel, R.; Hogerheijde, M. R.; Dominik, C.; Augereau, J. -C.; Matter, A.; Hron, J.; Pantin, E.; Rivinius, Th.; de Wit, W. -J.; Varga, J.; Klarmann, L.; Meisenheimer, K.; Gámez Rosas, V.; Burtscher, L.; Leftley, J.; Isbell, J. W.; Yoffe, G.; Kokoulina, E.; Danchi, W. C.; Cruzalèbes, P.; Domiciano de Souza, A.; Drevon, J.; Hocdé, V.; Kreplin, A.; Labadie, L.; Connot, C.; Nußbaum, E.; Lehmitz, M.; Antonelli, P.; Graser, U.; Leinert, C. Bibcode: 2022A&A...658A..81H Altcode: 2021arXiv211112458H Context. FS Canis Majoris (FS CMa, HD 45677) is an unclassified B[e] star surrounded by an inclined dust disk. The evolutionary stage of FS CMa is still debated. Perpendicular to the circumstellar disk, a bipolar outflow was detected. Infrared aperture-synthesis imaging provides us with a unique opportunity to study the disk structure.
Aims: Our aim is to study the intensity distribution of the disk of FS CMa in the mid-infrared L and N bands.
Methods: We performed aperture-synthesis imaging of FS CMa with the MATISSE instrument (Multi AperTure mid-Infrared SpectroScopic Experiment) in the low spectral resolution mode to obtain images in the L and N bands. We computed radiative transfer models that reproduce the L- and N-band intensity distributions of the resolved disks.
Results: We present L- and N-band aperture-synthesis images of FS CMa reconstructed in the wavelength bands of 3.4-3.8 and 8.6-9.0 μm. In the L-band image, the inner rim region of an inclined circumstellar disk and the central object can be seen with a spatial resolution of 2.7 milliarcsec (mas). An inner disk cavity with an angular diameter of ~6 × 12 mas is resolved. The L-band disk consists of a bright northwestern (NW) disk region and a much fainter southeastern (SE) region. The images suggest that we are looking at the bright inner wall of the NW disk rim, which is on the far side of the disk. In the N band, only the bright NW disk region is seen. In addition to deriving the inclination and the inner disk radius, fitting the reconstructed brightness distributions via radiative transfer modelling allows one to constrain the innermost disk structure, in particular the shape of theinner disk rim.

Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere within the commissioning of the VLTI-MATISSE instrument (ID 60.A-9257(E)). Title: Thermal imaging of dust hiding the black hole in NGC 1068 Authors: Gámez Rosas, Violeta; Isbell, Jacob W.; Jaffe, Walter; Petrov, Romain G.; Leftley, James H.; Hofmann, Karl-Heinz; Millour, Florentin; Burtscher, Leonard; Meisenheimer, Klaus; Meilland, Anthony; Waters, Laurens B. F. M.; Lopez, Bruno; Lagarde, Stéphane; Weigelt, Gerd; Berio, Philippe; Allouche, Fatme; Robbe-Dubois, Sylvie; Cruzalèbes, Pierre; Bettonvil, Felix; Henning, Thomas; Augereau, Jean-Charles; Antonelli, Pierre; Beckmann, Udo; van Boekel, Roy; Bendjoya, Philippe; Danchi, William C.; Dominik, Carsten; Drevon, Julien; Gallimore, Jack F.; Graser, Uwe; Heininger, Matthias; Hocdé, Vincent; Hogerheijde, Michiel; Hron, Josef; Impellizzeri, Caterina M. V.; Klarmann, Lucia; Kokoulina, Elena; Labadie, Lucas; Lehmitz, Michael; Matter, Alexis; Paladini, Claudia; Pantin, Eric; Pott, Jörg-Uwe; Schertl, Dieter; Soulain, Anthony; Stee, Philippe; Tristram, Konrad; Varga, Jozsef; Woillez, Julien; Wolf, Sebastian; Yoffe, Gideon; Zins, Gerard Bibcode: 2022Natur.602..403G Altcode: 2021arXiv211213694G In the widely accepted `unified model'1 solution of the classification puzzle of active galactic nuclei, the orientation of a dusty accretion torus around the central black hole dominates their appearance. In `type-1' systems, the bright nucleus is visible at the centre of a face-on torus. In `type-2' systems the thick, nearly edge-on torus hides the central engine. Later studies suggested evolutionary effects2 and added dusty clumps and polar winds3 but left the basic picture intact. However, recent high-resolution images4 of the archetypal type-2 galaxy NGC 10685,6, suggested a more radical revision. The images displayed a ring-like emission feature that was proposed to be hot dust surrounding the black hole at the radius where the radiation from the central engine evaporates the dust. That ring is too thin and too far tilted from edge-on to hide the central engine, and ad hoc foreground extinction is needed to explain the type-2 classification. These images quickly generated reinterpretations of the dichotomy between types 1 and 27,8. Here we present new multi-band mid-infrared images of NGC 1068 that detail the dust temperature distribution and reaffirm the original model. Combined with radio data (J.F.G. and C.M.V.I., manuscript in preparation), our maps locate the central engine that is below the previously reported ring and obscured by a thick, nearly edge-on disk, as predicted by the unified model. We also identify emission from polar flows and absorbing dust that is mineralogically distinct from that towards the Milky Way centre. Title: Simultaneous broadband radio and optical emission of meteor trains imaged by LOFAR / AARTFAAC and CAMS Authors: Dijkema, Tammo Jan; Bassa, Cees; Kuiack, Mark; Jenniskens, Peter; Johannink, Carl; Bettonvil, Felix; Wijers, Ralph; Fallows, Richard Bibcode: 2021JIMO...49..137D Altcode: 2021arXiv211109742D We report on simultaneous 30 - 60 MHz LOFAR / AARTFAAC12 radio observations and CAMS low-light video observations of +4 to -10 magnitude meteors at the peak of the Perseid meteor shower on August 12/13, 2020. 204 meteor trains were imaged in both the radio and optical domain. Aside from scattered artificial radio sources, we identify broadband radio emission from many persistent trains, one of which lingered for up to 6 minutes. Unexpectedly, fewer broadband radio meteor trains were recorded when the experiment was repeated during the 2020 Geminids and 2021 Quadrantids. Intrinsic broadband radio emission was reported earlier by the Long Wavelength Array, but for much brighter meteors and observed with lower spatial resolution. The new results offer insight into the unknown radio emission mechanism. Title: First MATISSE L-band observations of HD 179218. Is the inner 10 au region rich in carbon dust particles? Authors: Kokoulina, E.; Matter, A.; Lopez, B.; Pantin, E.; Ysard, N.; Weigelt, G.; Habart, E.; Varga, J.; Jones, A.; Meilland, A.; Dartois, E.; Klarmann, L.; Augereau, J. -C.; van Boekel, R.; Hogerheijde, M.; Yoffe, G.; Waters, L. B. F. M.; Dominik, C.; Jaffe, W.; Millour, F.; Henning, Th.; Hofmann, K. -H.; Schertl, D.; Lagarde, S.; Petrov, R. G.; Antonelli, P.; Allouche, F.; Berio, P.; Robbe-Dubois, S.; Ábraham, P.; Beckmann, U.; Bensberg, A.; Bettonvil, F.; Bristow, P.; Cruzalèbes, P.; Danchi, W. C.; Dannhoff, M.; Graser, U.; Heininger, M.; Labadie, L.; Lehmitz, M.; Leinert, C.; Meisenheimer, K.; Paladini, C.; Percheron, I.; Stee, Ph.; Woillez, J.; Wolf, S.; Zins, G.; Delbo, M.; Drevon, J.; Duprat, J.; Gámez Rosas, V.; Hocdé, V.; Hron, J.; Hummel, C. A.; Isbell, J. W.; Leftley, J.; Soulain, A.; Vakili, F.; Wittkowski, M. Bibcode: 2021A&A...652A..61K Altcode: 2021arXiv210612947K Context. Carbon is one of the most abundant components in the Universe. While silicates have been the main focus of solid phase studies in protoplanetary discs (PPDs), little is known about the solid carbon content especially in the planet-forming regions (~0.1-10 au). Fortunately, several refractory carbonaceous species present C-H bonds (such as hydrogenated nano-diamond and amorphous carbon as well as polycyclic aromatic hydrocarbons), which generate infrared (IR) features that can be used to trace the solid carbon reservoirs. The new mid-IR instrument MATISSE, installed at the Very Large Telescope Interferometer (VLTI), can spatially resolve the inner regions (~1-10 au) of PPDs and locate, down to the au-scale, the emission coming from carbon grains.
Aims: Our aim is to provide a consistent view on the radial structure, down to the au-scale, as well as basic physical properties and the nature of the material responsible for the IR continuum emission in the inner disk region around HD 179218.
Methods: We implemented a temperature-gradient model to interpret the disk IR continuum emission, based on a multiwavelength dataset comprising a broadband spectral energy distribution and VLTI H-, L-, and N-bands interferometric data obtained in low spectral resolution. Then, we added a ring-like component, representing the carbonaceous L-band features-emitting region, to assess its detectability in future higher spectral resolution observations employing mid-IR interferometry.
Results: Our temperature-gradient model can consistently reproduce our dataset. We confirmed a spatially extended inner 10 au emission in H- and L-bands, with a homogeneously high temperature (~1700 K), which we associate with the presence of stochastically heated nano-grains. On the other hand, the N-band emitting region presents a ring-like geometry that starts at about 10 au with a temperature of 400 K. Moreover, the existing low resolution MATISSE data exclude the presence of aromatic carbon grains (i.e., producing the 3.3 μm feature) in close proximity tothe star (≲1 au). Future medium spectral resolution MATISSE data will confirm their presence at larger distances.
Conclusions: Our best-fit model demonstrates the presence of two separated dust populations: nano-grains that dominate the near- to mid-IR emission in the inner 10 au region and larger grains that dominate the emission outward. The presence of such nano-grains in the highly irradiated inner 10 au region of HD 179218 requires a replenishment process. Considering the expected lifetime of carbon nano-grains from The Heterogeneous dust Evolution Model for Interstellar Solids (THEMIS model), the estimated disk accretion inflow of HD 179218 could significantly contribute to feed the inner 10 au region in nano-grains.Moreover, we also expect a local regeneration of those nano-grains by the photo-fragmentation of larger aggregates.

Based on observations collected at the European Southern Observatory, Chile (ESO ID: 0103.D-0069). Title: VLTI-MATISSE chromatic aperture-synthesis imaging of η Carinae's stellar wind across the Brα line. Periastron passage observations in February 2020 Authors: Weigelt, G.; Hofmann, K. -H.; Schertl, D.; Lopez, B.; Petrov, R. G.; Lagarde, S.; Berio, Ph.; Jaffe, W.; Henning, Th.; Millour, F.; Meilland, A.; Allouche, F.; Robbe-Dubois, S.; Matter, A.; Cruzalèbes, P.; Hillier, D. J.; Russell, C. M. P.; Madura, T.; Gull, T. R.; Corcoran, M. F.; Damineli, A.; Moffat, A. F. J.; Morris, P. W.; Richardson, N. D.; Paladini, C.; Schöller, M.; Mérand, A.; Glindemann, A.; Beckmann, U.; Heininger, M.; Bettonvil, F.; Zins, G.; Woillez, J.; Bristow, P.; Sanchez-Bermudez, J.; Ohnaka, K.; Kraus, S.; Mehner, A.; Wittkowski, M.; Hummel, C. A.; Stee, P.; Vakili, F.; Hartman, H.; Navarete, F.; Hamaguchi, K.; Espinoza-Galeas, D. A.; Stevens, I. R.; van Boekel, R.; Wolf, S.; Hogerheijde, M. R.; Dominik, C.; Augereau, J. -C.; Pantin, E.; Waters, L. B. F. M.; Meisenheimer, K.; Varga, J.; Klarmann, L.; Gámez Rosas, V.; Burtscher, L.; Leftley, J.; Isbell, J. W.; Hocdé, V.; Yoffe, G.; Kokoulina, E.; Hron, J.; Groh, J.; Kreplin, A.; Rivinius, Th.; de Wit, W. -J.; Danchi, W. -C.; Domiciano de Souza, A.; Drevon, J.; Labadie, L.; Connot, C.; Nußbaum, E.; Lehmitz, M.; Antonelli, P.; Graser, U.; Leinert, C. Bibcode: 2021A&A...652A.140W Altcode: Context. Eta Carinae is a highly eccentric, massive binary system (semimajor axis ~15.5 au) with powerful stellar winds and a phase-dependent wind-wind collision (WWC) zone. The primary star, η Car A, is a luminous blue variable (LBV); the secondary, η Car B, is a Wolf-Rayet or O star with a faster but less dense wind. Aperture-synthesis imaging allows us to study the mass loss from the enigmatic LBV η Car. Understanding LBVs is a crucial step toward improving our knowledge about massive stars and their evolution.
Aims: Our aim is to study the intensity distribution and kinematics of η Car's WWC zone.
Methods: Using the VLTI-MATISSE mid-infrared interferometry instrument, we perform Brα imaging of η Car's distorted wind.
Results: We present the first VLTI-MATISSE aperture-synthesis images of η Car A's stellar windin several spectral channels distributed across the Brα 4.052 μm line (spectral resolving power R ~ 960). Our observations were performed close to periastron passage in February 2020 (orbital phase ~ 14.0022). The reconstructed iso-velocity images show the dependence of the primary stellar wind on wavelength or line-of-sight (LOS) velocity with a spatial resolution of 6 mas (~14 au). The radius of the faintest outer wind regions is ~26 mas (~60 au). At several negative LOS velocities, the primary stellar wind is less extended to the northwest than in other directions. This asymmetry is most likely caused by the WWC. Therefore, we see both the velocity field of the undisturbed primary wind and the WWC cavity. In continuum spectral channels, the primary star wind is more compact than in line channels. A fit of the observed continuum visibilities with the visibilities of a stellar wind CMFGEN model (CMFGEN is an atmosphere code developed to model the spectra of a variety of objects) provides a full width at half maximum fit diameter of the primary stellar wind of 2.84 ± 0.06 mas (6.54 ± 0.14 au). We comparethe derived intensity distributions with the CMFGEN stellar wind model and hydrodynamic WWC models.

Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere under ESO program 0104.D-0015A, 0104.D-0015B, 0104.D-0015C, 0106.D-0309(A), 0106.D-0309(B), and 0106.D-0309(C). Title: Mid-infrared circumstellar emission of the long-period Cepheid ℓ Carinae resolved with VLTI/MATISSE Authors: Hocdé, V.; Nardetto, N.; Matter, A.; Lagadec, E.; Mérand, A.; Cruzalèbes, P.; Meilland, A.; Millour, F.; Lopez, B.; Berio, P.; Weigelt, G.; Petrov, R.; Isbell, J. W.; Jaffe, W.; Kervella, P.; Glindemann, A.; Schöller, M.; Allouche, F.; Gallenne, A.; Domiciano de Souza, A.; Niccolini, G.; Kokoulina, E.; Varga, J.; Lagarde, S.; Augereau, J. -C.; van Boekel, R.; Bristow, P.; Henning, Th.; Hofmann, K. -H.; Zins, G.; Danchi, W. -C.; Delbo, M.; Dominik, C.; Gámez Rosas, V.; Klarmann, L.; Hron, J.; Hogerheijde, M. R.; Meisenheimer, K.; Pantin, E.; Paladini, C.; Robbe-Dubois, S.; Schertl, D.; Stee, P.; Waters, R.; Lehmitz, M.; Bettonvil, F.; Heininger, M.; Bristow, P.; Woillez, J.; Wolf, S.; Yoffe, G.; Szabados, L.; Chiavassa, A.; Borgniet, S.; Breuval, L.; Javanmardi, B.; Ábrahám, P.; Abadie, S.; Abuter, R.; Accardo, M.; Adler, T.; Agócs, T.; Alonso, J.; Antonelli, P.; Böhm, A.; Bailet, C.; Bazin, G.; Beckmann, U.; Beltran, J.; Boland, W.; Bourget, P.; Brast, R.; Bresson, Y.; Burtscher, L.; Buter, R.; Castillo, R.; Chelli, A.; Cid, C.; Clausse, J. -M.; Connot, C.; Conzelmann, R. D.; De Haan, M.; Ebert, M.; Elswijk, E.; Fantei, Y.; Frahm, R.; Gámez Rosas, V.; Gabasch, A.; Garces, E.; Girard, P.; Glazenborg, A.; Gonté, F. Y. J.; González Herrera, J. C.; Graser, U.; Guajardo, P.; Guitton, F.; Hanenburg, H.; Haubois, X.; Hubin, N.; Huerta, R.; Idserda, J.; Ives, D.; Jakob, G.; Jaskó, A.; Jochum, L.; Klein, R.; Kragt, J.; Kroes, G.; Kuindersma, S.; Labadie, L.; Laun, W.; Le Poole, R.; Leinert, C.; Lizon, J. -L.; Lopez, M.; Marcotto, A.; Mauclert, N.; Maurer, T.; Mehrgan, L. H.; Meisner, J.; Meixner, K.; Mellein, M.; Mohr, L.; Morel, S.; Mosoni, L.; Navarro, R.; Neumann, U.; Nußbaum, E.; Pallanca, L.; Pasquini, L.; Percheron, I.; Phan Duc, T.; Pott, J. -U.; Pozna, E.; Ridinger, A.; Rigal, F.; Riquelme, M.; Rivinius, Th.; Roelfsema, R.; Rohloff, R. -R.; Rousseau, S.; Schuhler, N.; Schuil, M.; Shabun, K.; Soulain, A.; Stephan, C.; ter Horst, R.; Tromp, N.; Vakili, F.; van Duin, A.; Venema, L. B.; Vinther, J.; Wittkowski, M.; Wrhel, F. Bibcode: 2021A&A...651A..92H Altcode: 2021arXiv210317014H Context. The nature of circumstellar envelopes (CSEs) around Cepheids is a matter of ongoing debate. The physical origin of their infrared (IR) excess could be shown to either be made up of a shell of ionized gas, a dust envelope, or a combination of both.
Aims: This study is aimed at constraining the geometry and the IR excess of the environment of the bright long-period Cepheid ℓ Car (P = 35.5 days) at mid-IR wavelengths in order to understand its physical nature.
Methods: We first used photometric observations in various bands (from the visible domain to the infrared) and Spitzer Space Telescope spectroscopy to constrain the IR excess of ℓ Car. Then we analyzed the VLTI/MATISSE measurements at a specific phase of observation in order to determine the flux contribution as well as the size and shape of the environment of the star in the L band. Finally, we tested the hypothesis of a shell of ionized gas in order to model the IR excess.
Results: We report the first detection in the L band of a centro-symmetric extended emission around ℓ Car, of about 1.7 R in full width at half maximum, producing an excess of about 7.0% in this band.This latter value is used to calibrate the IR excess found when comparing the photometric observations in various bands and quasi-static atmosphere models. In the N band, there is no clear evidence for dust emission from VLTI/MATISSE correlated flux and Spitzer data. On the other side, the modeled shell of ionized gas implies a more compact CSE (1.13 ± 0.02 R) that is also fainter (IR excess of 1% in the L band).
Conclusions: We provide new evidence supporting a compact CSE for ℓ Car and we demonstrate the capabilities of VLTI/MATISSE for determining common properties of CSEs. While the compact CSE of ℓ Car is likely to be of a gaseous nature, the tested model of a shell of ionized gas is not able to simultaneously reproduce the IR excess and the interferometric observations. Further Galactic Cepheid observations with VLTI/MATISSE are necessary for determining the properties of CSEs, which may also depend on both the pulsation period and the evolutionary state of the stars.

Based on observations made with ESO telescopes at Paranal observatory under program ID 0104.D-0554(A). Title: Trajectory and orbit of the unique carbonaceous meteorite Flensburg Authors: Borovička, Jiří; Bettonvil, Felix; Baumgarten, Gerd; Strunk, Jörg; Hankey, Mike; Spurný, Pavel; Heinlein, Dieter Bibcode: 2021M&PS...56..425B Altcode: 2021arXiv210102177B The C1 ungrouped carbonaceous chondrite Flensburg fell in Germany on September 12, 2019, in the daytime. We determined the atmospheric trajectory, velocity, and heliocentric orbit using one dedicated AllSky6 meteor camera and three casual video records of the bolide. It was found that the meteorite originated in the vicinity of the 5:2 resonance with Jupiter at heliocentric distance of 2.82 AU. When combined with the bolide energy reported by the United States government sensors (USGS), the preatmospheric diameter of the meteoroid was estimated to be 2-3 m and the mass to be 10,000-20,000 kg. The meteoroid fragmented heavily in the atmosphere at heights of 46-37 km, under dynamic pressures of 0.7-2 MPa. The recovery of just one meteorite suggests that only a very small part of the original mass reached the ground. The bolide velocity vector was compared with that reported by the USGS. There is good agreement in the radiant but the velocity value has been underestimated by the USGS by almost 1 km s−1. Title: The asymmetric inner disk of the Herbig Ae star HD 163296 in the eyes of VLTI/MATISSE: evidence for a vortex? Authors: Varga, J.; Hogerheijde, M.; van Boekel, R.; Klarmann, L.; Petrov, R.; Waters, L. B. F. M.; Lagarde, S.; Pantin, E.; Berio, Ph.; Weigelt, G.; Robbe-Dubois, S.; Lopez, B.; Millour, F.; Augereau, J. -C.; Meheut, H.; Meilland, A.; Henning, Th.; Jaffe, W.; Bettonvil, F.; Bristow, P.; Hofmann, K. -H.; Matter, A.; Zins, G.; Wolf, S.; Allouche, F.; Donnan, F.; Schertl, D.; Dominik, C.; Heininger, M.; Lehmitz, M.; Cruzalèbes, P.; Glindemann, A.; Meisenheimer, K.; Paladini, C.; Schöller, M.; Woillez, J.; Venema, L.; Kokoulina, E.; Yoffe, G.; Ábrahám, P.; Abadie, S.; Abuter, R.; Accardo, M.; Adler, T.; Agócs, T.; Antonelli, P.; Böhm, A.; Bailet, C.; Bazin, G.; Beckmann, U.; Beltran, J.; Boland, W.; Bourget, P.; Brast, R.; Bresson, Y.; Burtscher, L.; Castillo, R.; Chelli, A.; Cid, C.; Clausse, J. -M.; Connot, C.; Conzelmann, R. D.; Danchi, W. -C.; De Haan, M.; Delbo, M.; Ebert, M.; Elswijk, E.; Fantei, Y.; Frahm, R.; Gámez Rosas, V.; Gabasch, A.; Gallenne, A.; Garces, E.; Girard, P.; Gonté, F. Y. J.; González Herrera, J. C.; Graser, U.; Guajardo, P.; Guitton, F.; Haubois, X.; Hron, J.; Hubin, N.; Huerta, R.; Isbell, J. W.; Ives, D.; Jakob, G.; Jaskó, A.; Jochum, L.; Klein, R.; Kragt, J.; Kroes, G.; Kuindersma, S.; Labadie, L.; Laun, W.; Le Poole, R.; Leinert, C.; Lizon, J. -L.; Lopez, M.; Mérand, A.; Marcotto, A.; Mauclert, N.; Maurer, T.; Mehrgan, L. H.; Meisner, J.; Meixner, K.; Mellein, M.; Mohr, L.; Morel, S.; Mosoni, L.; Navarro, R.; Neumann, U.; Nußbaum, E.; Pallanca, L.; Pasquini, L.; Percheron, I.; Pott, J. -U.; Pozna, E.; Ridinger, A.; Rigal, F.; Riquelme, M.; Rivinius, Th.; Roelfsema, R.; Rohloff, R. -R.; Rousseau, S.; Schuhler, N.; Schuil, M.; Soulain, A.; Stee, P.; Stephan, C.; ter Horst, R.; Tromp, N.; Vakili, F.; van Duin, A.; Vinther, J.; Wittkowski, M.; Wrhel, F. Bibcode: 2021A&A...647A..56V Altcode: 2020arXiv201205697V Context. A complex environment exists in the inner few astronomical units of planet-forming disks. High-angular-resolution observations play a key role in our understanding of the disk structure and the dynamical processes at work.
Aims: In this study we aim to characterize the mid-infrared brightness distribution of the inner disk of the young intermediate-mass star HD 163296 from early VLTI/MATISSE observations taken in the L- and N-bands. We put special emphasis on the detection of potential disk asymmetries.
Methods: We use simple geometric models to fit the interferometric visibilities and closure phases. Our models include a smoothed ring, a flat disk with an inner cavity, and a 2D Gaussian. The models can account for disk inclination and for azimuthal asymmetries as well. We also perform numerical hydrodynamical simulations of the inner edge of the disk.
Results: Our modeling reveals a significant brightness asymmetry in the L-band disk emission. The brightness maximum of the asymmetry is located at the NW part of the disk image, nearly at the position angle of the semimajor axis. The surface brightness ratio in the azimuthal variation is 3.5 ± 0.2. Comparing our result on the location of the asymmetry with other interferometric measurements, we confirm that the morphology of the r < 0.3 au disk region is time-variable. We propose that this asymmetric structure, located in or near the inner rim of the dusty disk, orbits the star. To find the physical origin of the asymmetry, we tested a hypothesis where a vortex is created by Rossby wave instability, and we find that a unique large-scale vortex may be compatible with our data. The half-light radius of the L-band-emitting region is 0.33 ±0.01 au, the inclination is 52°-7°+5°, and the position angle is 143° ± 3°. Our models predict that a non-negligible fraction of the L-band disk emission originates inside the dust sublimation radius for μm-sized grains. Refractory grains or large (≳10 μm-sized) grains could be the origin of this emission. N-band observations may also support a lack of small silicate grains in the innermost disk (r ≲ 0.6 au), in agreement with our findings from L-band data.

Based on observations made with ESO Telescopes at the La Silla Paranal Observatory under program IDs 0103.D-0294 and 0103.D-0153. Title: METIS: The Mid-infrared ELT Imager and Spectrograph Authors: Brandl, B.; Bettonvil, F.; van Boekel, R.; Glauser, A.; Quanz, S.; Absil, O.; Amorim, A.; Feldt, M.; Glasse, A.; Güdel, M.; Ho, P.; Labadie, L.; Meyer, M.; Pantin, E.; van Winckel, H.; METIS Consortium Bibcode: 2021Msngr.182...22B Altcode: 2021arXiv210311208B The Mid-infrared ELT Imager and Spectrograph (METIS) will provide the Extremely Large Telescope (ELT) with a unique window to the thermal- and mid-infrared (3-13 µm). Its single-conjugate adaptive optics (SCAO) system will enable high contrast imaging and integral field unit (IFU) spectroscopy (R ~ 100 000) at the diffraction limit of the ELT. This article describes the science drivers, conceptual design, observing modes, and expected performance of METIS. Title: FRIPON: a worldwide network to track incoming meteoroids Authors: Colas, F.; Zanda, B.; Bouley, S.; Jeanne, S.; Malgoyre, A.; Birlan, M.; Blanpain, C.; Gattacceca, J.; Jorda, L.; Lecubin, J.; Marmo, C.; Rault, J. L.; Vaubaillon, J.; Vernazza, P.; Yohia, C.; Gardiol, D.; Nedelcu, A.; Poppe, B.; Rowe, J.; Forcier, M.; Koschny, D.; Trigo-Rodriguez, J. M.; Lamy, H.; Behrend, R.; Ferrière, L.; Barghini, D.; Buzzoni, A.; Carbognani, A.; Di Carlo, M.; Di Martino, M.; Knapic, C.; Londero, E.; Pratesi, G.; Rasetti, S.; Riva, W.; Stirpe, G. M.; Valsecchi, G. B.; Volpicelli, C. A.; Zorba, S.; Coward, D.; Drolshagen, E.; Drolshagen, G.; Hernandez, O.; Jehin, E.; Jobin, M.; King, A.; Nitschelm, C.; Ott, T.; Sanchez-Lavega, A.; Toni, A.; Abraham, P.; Affaticati, F.; Albani, M.; Andreis, A.; Andrieu, T.; Anghel, S.; Antaluca, E.; Antier, K.; Appéré, T.; Armand, A.; Ascione, G.; Audureau, Y.; Auxepaules, G.; Avoscan, T.; Baba Aissa, D.; Bacci, P.; Bǎdescu, O.; Baldini, R.; Baldo, R.; Balestrero, A.; Baratoux, D.; Barbotin, E.; Bardy, M.; Basso, S.; Bautista, O.; Bayle, L. D.; Beck, P.; Bellitto, R.; Belluso, R.; Benna, C.; Benammi, M.; Beneteau, E.; Benkhaldoun, Z.; Bergamini, P.; Bernardi, F.; Bertaina, M. E.; Bessin, P.; Betti, L.; Bettonvil, F.; Bihel, D.; Birnbaum, C.; Blagoi, O.; Blouri, E.; Boacă, I.; Boatǎ, R.; Bobiet, B.; Bonino, R.; Boros, K.; Bouchet, E.; Borgeot, V.; Bouchez, E.; Boust, D.; Boudon, V.; Bouman, T.; Bourget, P.; Brandenburg, S.; Bramond, Ph.; Braun, E.; Bussi, A.; Cacault, P.; Caillier, B.; Calegaro, A.; Camargo, J.; Caminade, S.; Campana, A. P. C.; Campbell-Burns, P.; Canal-Domingo, R.; Carell, O.; Carreau, S.; Cascone, E.; Cattaneo, C.; Cauhape, P.; Cavier, P.; Celestin, S.; Cellino, A.; Champenois, M.; Chennaoui Aoudjehane, H.; Chevrier, S.; Cholvy, P.; Chomier, L.; Christou, A.; Cricchio, D.; Coadou, P.; Cocaign, J. Y.; Cochard, F.; Cointin, S.; Colombi, E.; Colque Saavedra, J. P.; Corp, L.; Costa, M.; Costard, F.; Cottier, M.; Cournoyer, P.; Coustal, E.; Cremonese, G.; Cristea, O.; Cuzon, J. C.; D'Agostino, G.; Daiffallah, K.; Dǎnescu, C.; Dardon, A.; Dasse, T.; Davadan, C.; Debs, V.; Defaix, J. P.; Deleflie, F.; D'Elia, M.; De Luca, P.; De Maria, P.; Deverchère, P.; Devillepoix, H.; Dias, A.; Di Dato, A.; Di Luca, R.; Dominici, F. M.; Drouard, A.; Dumont, J. L.; Dupouy, P.; Duvignac, L.; Egal, A.; Erasmus, N.; Esseiva, N.; Ebel, A.; Eisengarten, B.; Federici, F.; Feral, S.; Ferrant, G.; Ferreol, E.; Finitzer, P.; Foucault, A.; Francois, P.; Frîncu, M.; Froger, J. L.; Gaborit, F.; Gagliarducci, V.; Galard, J.; Gardavot, A.; Garmier, M.; Garnung, M.; Gautier, B.; Gendre, B.; Gerard, D.; Gerardi, A.; Godet, J. P.; Grandchamps, A.; Grouiez, B.; Groult, S.; Guidetti, D.; Giuli, G.; Hello, Y.; Henry, X.; Herbreteau, G.; Herpin, M.; Hewins, P.; Hillairet, J. J.; Horak, J.; Hueso, R.; Huet, E.; Huet, S.; Hyaumé, F.; Interrante, G.; Isselin, Y.; Jeangeorges, Y.; Janeux, P.; Jeanneret, P.; Jobse, K.; Jouin, S.; Jouvard, J. M.; Joy, K.; Julien, J. F.; Kacerek, R.; Kaire, M.; Kempf, M.; Koschny, D.; Krier, C.; Kwon, M. K.; Lacassagne, L.; Lachat, D.; Lagain, A.; Laisné, E.; Lanchares, V.; Laskar, J.; Lazzarin, M.; Leblanc, M.; Lebreton, J. P.; Lecomte, J.; Le Dû, P.; Lelong, F.; Lera, S.; Leoni, J. F.; Le-Pichon, A.; Le-Poupon, P.; Leroy, A.; Leto, G.; Levansuu, A.; Lewin, E.; Lienard, A.; Licchelli, D.; Locatelli, H.; Loehle, S.; Loizeau, D.; Luciani, L.; Maignan, M.; Manca, F.; Mancuso, S.; Mandon, E.; Mangold, N.; Mannucci, F.; Maquet, L.; Marant, D.; Marchal, Y.; Marin, J. L.; Martin-Brisset, J. C.; Martin, D.; Mathieu, D.; Maury, A.; Mespoulet, N.; Meyer, F.; Meyer, J. Y.; Meza, E.; Moggi Cecchi, V.; Moiroud, J. J.; Millan, M.; Montesarchio, M.; Misiano, A.; Molinari, E.; Molau, S.; Monari, J.; Monflier, B.; Monkos, A.; Montemaggi, M.; Monti, G.; Moreau, R.; Morin, J.; Mourgues, R.; Mousis, O.; Nablanc, C.; Nastasi, A.; Niacşu, L.; Notez, P.; Ory, M.; Pace, E.; Paganelli, M. A.; Pagola, A.; Pajuelo, M.; Palacián, J. F.; Pallier, G.; Paraschiv, P.; Pardini, R.; Pavone, M.; Pavy, G.; Payen, G.; Pegoraro, A.; Peña-Asensio, E.; Perez, L.; Pérez-Hoyos, S.; Perlerin, V.; Peyrot, A.; Peth, F.; Pic, V.; Pietronave, S.; Pilger, C.; Piquel, M.; Pisanu, T.; Poppe, M.; Portois, L.; Prezeau, J. F.; Pugno, N.; Quantin, C.; Quitté, G.; Rambaux, N.; Ravier, E.; Repetti, U.; Ribas, S.; Richard, C.; Richard, D.; Rigoni, M.; Rivet, J. P.; Rizzi, N.; Rochain, S.; Rojas, J. F.; Romeo, M.; Rotaru, M.; Rotger, M.; Rougier, P.; Rousselot, P.; Rousset, J.; Rousseu, D.; Rubiera, O.; Rudawska, R.; Rudelle, J.; Ruguet, J. P.; Russo, P.; Sales, S.; Sauzereau, O.; Salvati, F.; Schieffer, M.; Schreiner, D.; Scribano, Y.; Selvestrel, D.; Serra, R.; Shengold, L.; Shuttleworth, A.; Smareglia, R.; Sohy, S.; Soldi, M.; Stanga, R.; Steinhausser, A.; Strafella, F.; Sylla Mbaye, S.; Smedley, A. R. D.; Tagger, M.; Tanga, P.; Taricco, C.; Teng, J. P.; Tercu, J. O.; Thizy, O.; Thomas, J. P.; Tombelli, M.; Trangosi, R.; Tregon, B.; Trivero, P.; Tukkers, A.; Turcu, V.; Umbriaco, G.; Unda-Sanzana, E.; Vairetti, R.; Valenzuela, M.; Valente, G.; Varennes, G.; Vauclair, S.; Vergne, J.; Verlinden, M.; Vidal-Alaiz, M.; Vieira-Martins, R.; Viel, A.; Vîntdevarǎ, D. C.; Vinogradoff, V.; Volpini, P.; Wendling, M.; Wilhelm, P.; Wohlgemuth, K.; Yanguas, P.; Zagarella, R.; Zollo, A. Bibcode: 2020A&A...644A..53C Altcode: 2020arXiv201200616C Context. Until recently, camera networks designed for monitoring fireballs worldwide were not fully automated, implying that in case of a meteorite fall, the recovery campaign was rarely immediate. This was an important limiting factor as the most fragile - hence precious - meteorites must be recovered rapidly to avoid their alteration.
Aims: The Fireball Recovery and InterPlanetary Observation Network (FRIPON) scientific project was designed to overcome this limitation. This network comprises a fully automated camera and radio network deployed over a significant fraction of western Europe and a small fraction of Canada. As of today, it consists of 150 cameras and 25 European radio receivers and covers an area of about 1.5 × 106 km2.
Methods: The FRIPON network, fully operational since 2018, has been monitoring meteoroid entries since 2016, thereby allowing the characterization of their dynamical and physical properties. In addition, the level of automation of the network makes it possible to trigger a meteorite recovery campaign only a few hours after it reaches the surface of the Earth. Recovery campaigns are only organized for meteorites with final masses estimated of at least 500 g, which is about one event per year in France. No recovery campaign is organized in the case of smaller final masses on the order of 50 to 100 g, which happens about three times a year; instead, the information is delivered to the local media so that it can reach the inhabitants living in the vicinity of the fall.
Results: Nearly 4000 meteoroids have been detected so far and characterized by FRIPON. The distribution of their orbits appears to be bimodal, with a cometary population and a main belt population. Sporadic meteors amount to about 55% of all meteors. A first estimate of the absolute meteoroid flux (mag < -5; meteoroid size ≥~1 cm) amounts to 1250/yr/106 km2. This value is compatible with previous estimates. Finally, the first meteorite was recovered in Italy (Cavezzo, January 2020) thanks to the PRISMA network, a component of the FRIPON science project. Title: Ge immersed grating manufacturing and optical verification for the METIS high-resolution spectrograph Authors: Agócs, Tibor; Elswijk, Eddy; Zaalberg, Daan; Peterzon, Jan Rinze; Tromp, Niels; Lloro, Ivan; Lynn, Jeffrey; Navarro, Ramon; Sukegawa, Takashi; Okura, Yukinobu; Todd, Stephen; Glasse, Alistair; Parr-Burman, Philip; Brandl, Bernhard; Bettonvil, Felix Bibcode: 2020SPIE11451E..1GA Altcode: We present the manufacturing and optical verification of the germanium immersed grating for the L/M band high resolution spectrograph (LMS). The LMS is one of the science subsystems of the Mid-infrared ELT Imager and Spectrograph, METIS. The immersed grating has very demanding requirement specifications: <100 nm RMS transmitted Wave Front Error (WFE) after double pass, and >70% peak throughput in all orders within the 2.9-5.3 μm wavelength range over the pupil. The grating has a period of 18.2 μm, a sawtooth groove profile with 89.6 degrees apex angle and a grating area of 150mm x 60mm. The germanium immersed grating was produced by Canon's high precision mechanical cutting technology. We present the interferometric tests that were performed in order to verify WFE and two different measurements (based on cascade laser and Fourier Transform Spectrometer, respectively) for throughput verification. Title: In memoriam: Hugo van Woerden (1926 - 2020) Authors: Bettonvil, Felix Bibcode: 2020JIMO...48..163B Altcode: On September 4, 2020, Prof. Dr. Hugo van Woerden passed away at the age of 94 after a short illness. Hugo was both an amateur and famous professional astronomer. In 1946, he was one of the founders of the Meteor Section of the Royal Netherlands Association for Meteorology and Astronomy (KNVWS Werkgroep Meteoren), and invented the use of star fields to determine the observer's limiting magnitude. Van Woerden was professor in radio astronomy, made famous by his work at the Kapteyn Institute in Groningen and among the first practicing radio astronomy in the Netherlands, and carried out important research with the Dwingeloo and Westerbork radio telescopes. Title: Warm calibration unit of the mid-infrared E-ELT instrument METIS: overview and current status of the project Authors: Rutowska, Monika; Sharma, Tarun; Wiest, Michael; Graf, Sabine; Straubmeier, Christian; Rost, Steffen; Labadie, Lucas; Eckart, Andreas; Burtscher, Leonard; Agócs, Tibor; Lesman, Dirk; Stuik, Remko; Glauser, Adrian; Brandl, Bernhard; Bettonvil, Felix Bibcode: 2020SPIE11447E..2TR Altcode: The warm calibration unit (WCU) is one subsystem of the future METIS instrument on the European Extremely Large Telescope (E-ELT). Operating at daytime temperature, the WCU is mounted above the main cryostat of METIS and will be employed as calibration reference for science observations, as well as for verification and alignment purposes during the AIT phase. The WCU is designed and constructed at the University of Cologne, partner in the METIS consortium. The WCU, together with the full METIS instrument, went recently through a successful preliminary design review (PDR) phase at ESO and is entering now the Phase C of the project. In this paper, we present the current status of the WCU and summarize the mostly mechanical and optical engineering work. We adopted a hexapod unit to interface with the METIS cryostat and a CFRP-based optical bench to optimally cope with alignment flexure. We develop the case for fiber-fed laser sources feeding the integrating sphere for spectral calibration of the LM-Spectrograph of METIS. We detail the activity foreseen for Phase C including the optical tolerances analysis, the eigenfrequency and earthquake analysis and a preparation of the sub-system MAIT work, finishing the paper with a short overview of the WCU future plans. Title: Another Daylight Fireball over The Netherlands: The event of 2020 August 25 Authors: Bettonvil, Felix Bibcode: 2020JIMO...48..185B Altcode: In recent years, we notice that more daylight fireballs are reported. This initiated the development and installation of a dedicated daylight all sky camera, aiming at capturing such events with good quality. On the 25th of August 2020, yet another daylight fireball appeared, around sunset, which was captured by the daylight camera. 240 fireball reports were received. We report on the results and analysis. Title: In memoriam Hugo van Woerden (1926 - 2020) Authors: Bettonvil, Felix Bibcode: 2020eMetN...5..362B Altcode: On September 4, 2020, Prof. Dr. Hugo van Woerden, after a short illness, passed away at the age of 94. Hugo was both amateur and famous professional astronomer, and one of the founders of the Meteor Section of the Royal Dutch Association for Astronomy and Meteorology (KNVWS Werkgroep Meteoren), in 1946, and inventor of the use of star fields to determine the observer's limiting magnitude. Hugo van Woerden was professor in radio astronomy at the Kapteyn Institute in Groningen and among the first practicing radio astronomy in the Netherlands, and carried out important research with the Dwingeloo and Westerbork radio telescopes. Title: Detection of polarization neutral points in observations of the combined corona and sky during the 21 August 2017 total solar eclipse Authors: Snik, Frans; Bos, Steven P.; Brackenhoff, Stefanie A.; Doelman, David S.; Por, Emiel H.; Bettonvil, Felix; Rodenhuis, Michiel; Vorobiev, Dmitry; Eshelman, Laura M.; Shaw, Joseph A. Bibcode: 2020ApOpt..59F..71S Altcode: 2020arXiv200712482S We report the results of polarimetric observations of the total solar eclipse of 21 August 2017 from Rexburg, Idaho (USA). We use three synchronized DSLR cameras with polarization filters oriented at 0°, 60°, and 120° to provide high-dynamic-range RGB polarization images of the corona and surrounding sky. We measure tangential coronal polarization and vertical sky polarization, both as expected. These observations provide detailed detections of polarization neutral points above and below the eclipsed Sun where the coronal polarization is canceled by the sky polarization. We name these special polarization neutral points after Minnaert and Van de Hulst. Title: Conference summary Authors: Bettonvil, Felix Bibcode: 2020pimo.conf..158B Altcode: Without doubt we can say that the 2019 IMC in Bollmansruh was once again a great success. During the four days a plethora of topics was presented, covering the wide scope of meteor science well. Instrumental development, software tools, observational results, analysis, modelling as well as public awareness was discussed, on an exciting conference location and in a great atmosphere with participants of all ages, both amateur and professional. Great achievements have been in the realization of very large camera networks, the availability of handy software tools and cross fertilization between disciplines and areas of interest. Meteor science is clearly broadening, making it very exciting. Title: Daytime fireball capturing Authors: Bettonvil, Felix Bibcode: 2020pimo.conf..135B Altcode: Traditionally, fireball patrol cameras are constructed to capture fireballs during night time. Fireballs nonetheless – and in particular meteorite dropping ones – do not only appear at night time: there a various examples of great fireballs that did appear at twilight or even daytime. In an attempt to have also daytime coverage I will present some recent test work on a panoramic surveillance cam. Title: Status of the mid-IR ELT imager and spectrograph (METIS) Authors: Brandl, Bernhard R.; Absil, Olivier; Agócs, Tibor; Baccichet, Nicola; Bertram, Thomas; Bettonvil, Felix; van Boekel, Roy; Burtscher, Leonard; van Dishoeck, Ewine; Feldt, Markus; Garcia, Paulo J. V.; Glasse, Alistair; Glauser, Adrian; Güdel, Manuel; Haupt, Christoph; Kenworthy, Matthew A.; Labadie, Lucas; Laun, Werner; Lesman, Dirk; Pantin, Eric; Quanz, Sascha P.; Snellen, Ignas; Siebenmorgen, Ralf; van Winckel, Hans Bibcode: 2018SPIE10702E..1UB Altcode: The Mid-Infrared ELT Imager and Spectrograph (METIS) is one of three first light instruments on the ELT. It will provide high-contrast imaging and medium resolution, slit-spectroscopy from 3 - 19um, as well as high resolution (R 100,000) integral field spectroscopy from 2.9-5.3µm. All modes observe at the diffraction limit of the ELT, by means of adaptive optics, yielding angular resolutions of a few tens of milliarcseconds. The range of METIS science is broad, from Solar System objects to active galactic nuclei (AGN). We will present an update on the main science drivers for METIS: circum-stellar disks and exoplanets. The METIS project is now in full steam, approaching its preliminary design review (PDR) in 2018. In this paper we will present the current status of its optical, mechanical and thermal design as well as operational aspects. We will also discuss the challenges of building an instrument for the ELT, and the required technologies. Title: The calibration unit of the mid-infrared E-ELT instrument METIS Authors: Baccichet, Nicola; Labadie, Lucas; Rost, Steffen; Straubmeier, Christian; Wiest, Michael; Burtscher, Leonard; Agócs, Tibor; Jellema, Willem; Roelfsema, Ronald; van Boekel, Roy; Glauser, Adrian; Brandl, Bernhard; Bettonvil, Felix; Lynn, Jeff; Eckart, Andreas Bibcode: 2018SPIE10702E..91B Altcode: We present the preliminary design of the calibration unit of the future E-ELT instrument METIS. This independent subunit is mounted externally to the main cryostat of METIS and will function both as calibration reference for science observations, as well as verification and alignment tool during the AIT phase. In this paper, we focus on describing its preliminary layout and foreseen functionalities, based on the performance requirements defined at system level and the constraints imposed by warm IR background. We discuss the advantage of employing an integrating sphere as common radiation emitter, leading to a novel and versatile design, where the source's spatio-spectral properties can be varied with high fidelity and repeatability. By combining only few tuneable sources and mechanisms we show how a large instrument such as METIS can be calibrated and tested, without the need of a complex cold calibration unit. Title: The warm calibration unit of METIS: optical design and principle of operation Authors: Straubmeier, Christian; Baccichet, Nicola; Labadie, Lucas; Rost, Steffen; Wiest, Michael; Eckart, Andreas; Brandl, Bernhard; Agócs, Tibor; Roelfsema, Ronald; Lynn, Jeffrey; Bettonvil, Felix Bibcode: 2018SPIE10702E..8PS Altcode: METIS, a mid-infrared imager and spectrograph for the wavelength range 2.9-19μm (astronomical L-, M-, N- and Q-band), will be one of the first three science instruments at the European Extremely Large Telescope (E-ELT). It will provide diffraction limited imaging, coronagraphy, high resolution integral field spectroscopy and low and medium resolution slit spectroscopy. Within the international METIS consortium, the 1st Institute of Physics of the University of Cologne in Germany is responsible for the design, manufacturing, integration and qualification of the Warm Calibration Unit (WCU) of the instrument. The WCU will be a self-contained unit operating at ambient temperature outside of the voluminous METIS dewar, feeding a variety of optical calibration and alignment signals into the optical path of METIS. The functionalities of the WCU will be used for routine daily daytime calibrations after astronomical observing nights and verification of the internal alignment of METIS during assembly, integration and verification (AIV). In this contribution we present the preliminary optical design and principle of operation of the WCU in its current state of the preliminary design phase of METIS. Title: The installation and ongoing commissioning of the MATISSE mid-infrared interferometer at the ESO Very Large Telescope Observatory Authors: Lopez, B.; Lagarde, S.; Matter, A.; Agocs, T.; Allouche, F.; Antonelli, P.; Augereau, J. -C.; Bailet, C.; Berio, P.; Bettonvil, F.; Beckmann, U.; van Boekel, R.; Bresson, Y.; Bristow, P.; Cruzalebes, P.; Delbo, M.; Dominik, C.; Elswijk, E.; Fantei, Y.; Glindemann, A.; Heininger, M.; Hofmann, K. -H.; Hogerheijde, M.; Hron, J.; Jaffe, W.; Kroes, G.; Laun, W.; Lehmitz, M.; Meilland, A.; Meisenheimer, K.; Millour, F.; Morel, S.; Neumann, U.; Pantin, E.; Petrov, R. G.; Robbe-Dubois, S.; Schertl, D.; Schoeller, M.; Wolf, S.; Zins, G.; Henning, T.; Stee, Ph.; Weigelt, G. Bibcode: 2018SPIE10701E..0ZL Altcode: MATISSE is the second-generation mid-infrared spectrograph and imager for the Very Large Telescope Interferometer (VLTI) at Paranal. This new interferometric instrument will allow significant advances in various fundamental research fields: studying the planet-forming region of disks around young stellar objects, understanding the surface structures and mass loss phenomena affecting evolved stars, and probing the environments of black holes in active galactic nuclei. As a first breakthrough, MATISSE will enlarge the spectral domain of current optical interferometers by offering the L and M bands in addition to the N band. This will open a wide wavelength domain, ranging from 2.8 to 13 μm, exploring angular scales as small as 3 mas (L band) / 10 mas (N band). As a second breakthrough, MATISSE will allow mid-infrared imaging - closure-phase aperture-synthesis imaging - with the four Unit Telescopes (UT) or Auxiliary Telescopes (AT) of the VLTI. Moreover, MATISSE will offer a spectral resolution range from R 30 to R 5000. Here, we remind the concept, the instrumental design, and the main features of MATISSE. We also describe the last months of preparation, the status of the instrument, which was shipped to Cerro Paranal on the site of the ESO Very Large Telescope in October 2017, and the expected schedule for the opening to the community. The instrument is currently in its Commissioning phase. A complementary dedicated article details the Commissioning results, which include the first performance estimates on sky. Title: The MATISSE photometric slider: achieving sub-micrometer reproducibility under cryogenic conditions Authors: Bettonvil, Felix C. M.; Kroes, G.; Elswijk, E.; de Haan, M.; ter Horst, R.; Kragt, J.; Navarro, R.; Schuil, M.; Tromp, T. Bibcode: 2018SPIE10706E..1AB Altcode: MATISSE is the mid-infrared interferometric spectrograph and imager for ESO's Very Large Telescope Interferometer (VLTI). A core mechanism inside the Cold Optical bench is the photometric slider, that enables the choice of observation with or without photometric beams which is achieved by sliding in 4 mirrors or 4 beam splitters into the four telescope beams. To achieve the stringent requirements on beam precision -which asks for mounting pad differences of order of 1 micrometer- all optical components were mounted on a single body and one lapped surface. Test results on the final instrument showed behavior significantly outside specification suggesting contact point height differences up to 6 micrometer. Also repeatability was non-compliant. We will present the cause analysis, the suspected culprit, unsuspected side effects and the implementation of the final solution which lead to a photometric slider well within specification. Title: MATISSE: performance in laboratory, results of AIV in Paranal, and first results on sky Authors: Robbe-Dubois, S.; Lagarde, S.; Antonelli, P.; Lopez, B.; Allouche, F.; Bailet, C.; Berio, Ph.; Bresson, Y.; Clausse, J. -M.; Cruzalèbes, P.; Fantei-Caujolle, Y.; Marcotto, A.; Matter, A.; Meilland, A.; Millour, F.; Morel, S.; Petrov, R. G.; Rousseau, S.; Soulain, A.; Zins, G.; Lehmitz, M.; Laun, W.; Adler, T.; Klein, R.; Maurer, T.; Bettonvil, F.; Eldswick, E.; Beckmann, U.; Heininger, M.; Bristow, P.; Glindemann, A.; Hubin, N.; Jochum, L.; Rivinus, Th.; Schoeller, M.; Beltran, J.; Bourget, P.; Gallenne, A.; Guerlet, Th.; Haubois, X.; Ives, D.; Jakob, G.; Meister, A.; Riquelme, M.; Schuhler, N.; Stephan, C.; Toledo, P.; Tristam, K.; Woillez, J.; Neumann, U.; Chelli, A.; Guitton, F.; Meisenheimer, K.; Pichon, B.; Spang, A.; Varga, J.; Henning, Th.; Jaffe, W.; Pasquini, L.; Stee, Ph.; Weigelt, G. Bibcode: 2018SPIE10701E..0HR Altcode: MATISSE (Multi AperTure mid-Infrared SpectroScopic Experiment) is the spectro-interferometer for the VLTI of the European Southern Observatory (ESO), operating in the L-, M- and N- spectral bands, and combining up to four beams from the unit or the auxiliary telescopes (UTs or ATs). MATISSE will offer new breakthroughs in the study of circumstellar environments by allowing the mapping of the material distribution, the gas and essentially the dust. The instrument consists in a warm optical system (WOP) accepting four beams from the VLTI and relaying them after a spectral splitting to cold optical benches (COB) located in two separate cryostats, one in L-M- band, and one in N-band. The test plan of the complete instrument has been conducted at the Observatoire de la Côte d'Azur in order to confirm the compliance of the performance with the high-level requirements. MATISSE has successfully passed the Preliminary Acceptance in Europe the 12th September 2017. Following this result, ESO gave approval for the instrument to be shipped to Paranal. The Alignment, Integration and Verification phase was conducted until end of February 2018, at the end of which first observations on sky have been performed to test the operations with the VLTI and to obtain first stellar light. The two first runs of the commissioning followed, respectively in March and in May 2018. It has the goal to optimize the MATISSE-VLTI communication, the acquisition procedures and the interface parameters. The observations were performed on bright L-M- and N- stars, with four ATs located on short baselines and UTs. The limit magnitudes will be deduced. This paper reports on the performance of the instrument measured in laboratory (results of test plan in Nice and AIV in Paranal) in terms of spectral coverage, dispersion laws and spectral resolutions, and transfer function analysis: instrumental contrast, visibility accuracy, accuracy of the differential phase, of the closure-phase and of the differential visibility. It also provides results of the first tests on sky and the planning of the on-going commissioning. Title: The Mid-IR ELT Imager and Spectrograph (METIS) and its Science Goals in the Context of AKARI Authors: Brandl, Bernhard R.; Quanz, Sascha; Snellen, Ignas; van Dishoeck, Ewine; Pontoppidan, Klaus; Le Floch, Emeric; Bettonvil, Felix; van Boekel, Roy; Glauser, Adrian; Hurtado, Norma Bibcode: 2018cwla.conf...41B Altcode: The Mid-infrared ELT Imager and Spectrograph (METIS) is one the first three scientific instruments on ESO's Extremely Large Telescope (ELT). At the time of anticipated first light in 2025, METIS will provide diffraction limited imaging, coronagraphy and medium resolution slit spectroscopy in the 3-19 micrometers range, as well as high resolution (R approximately equals to 100, 000) integral field spectroscopy from 2.9-5.3 micrometers. The unique combination of these observing capabilities with an angular resolution of 0.020 sec, and the sensitivity provided by a 40m aperture, make METIS a very powerful tool to study the infrared sky - from objects in our Solar system, the Galactic center, brown dwarfs, evolved stars, and massive stellar clusters to active galactic nuclei (AGN), local starbursts, transient events, and luminous infrared galaxies at intermediate redshifts. Its main scientific focus, however, will be on the study of proto-planetary disks and exoplanets. In this paper, we describe the instrument concept and performance. We discuss the scientific performance of METIS with respect to AKARI, and elaborate on the relevance of the AKARI archive with respect to the METIS observing program. Title: Meteorite detection with airborne support—a study case Authors: Zender, Joe; Rudawska, Regina; Koschny, Detlef; Drolshagen, Gerhard; Netjes, Gert-Jan; Bosch, Mirko; Bijl, Rik; Crevecoeur, Rob; Bettonvil, Felix Bibcode: 2018pimo.conf..145Z Altcode: The search for meteorites is a cumbersome and tough activity. After having instrumental evidence, i.e., the detection of fireballs in one of the existing fireball networks and the computation of the potential landing site area, a group of enthousiasts often spends days in the search for meteorites. This study analyses if the use of airborne cameras can support the meteorite search. A set of 11 test meteorites was distributed on two different kind of surface areas: a grass field and a harvested wheat field. A high-resolution camera mounted on a drone acquired images at 60 meters altitude. The images were post-processed to identify the meteorites. The algorithm detected at least half of the meteorites. Title: Preliminary optical design for the common fore optics of METIS Authors: Agócs, Tibor; Brandl, Bernhard R.; Jager, Rieks; Bettonvil, Felix; Aitink-Kroes, Gabby; Venema, Lars; Kenworthy, Matthew; Absil, Olivier; Bertram, Thomas Bibcode: 2016SPIE.9908E..9QA Altcode: METIS is the Mid-infrared E-ELT Imager and Spectrograph, which will provide outstanding observing capabilities, focusing on high angular and spectral resolution. It consists of two diffraction-limited imagers operating in the LM and NQ bands respectively and an IFU fed diffraction-limited high-resolution (R=100,000) LM band spectrograph. These science subsystems are preceded by the common fore optics (CFO), which provides the following essential functionalities: calibration, chopping, image de-rotation, thermal background and stray light reduction. We show the evolution of the CFO optical design from the conceptual design to the preliminary optical design, detail the optimization steps and discuss the necessary trade-offs. Title: MATISSE: alignment, integration, and test phase first results Authors: Allouche, F.; Robbe-Dubois, S.; Lagarde, S.; Cruzalèbes, P.; Antonelli, P.; Bresson, Y.; Fantei-Caujolle, Y.; Marcotto, A.; Morel, S.; Beckmann, U.; Bettonvil, F.; Berio, Ph.; Heininger, M.; Lehmitz, M.; Agocs, T.; Brast, R.; Elswijk, E.; Ives, D.; Meixner, K.; Laun, W.; Mellein, M.; Neumann, U.; Bailet, C.; Clausse, J. -M.; Matter, A.; Meilland, A.; Millour, F.; Petrov, R. G.; Accardo, M.; Bristow, P.; Frahm, R.; Glindemann, A.; Gonzáles Herrera, J. -C.; Lizon, J. -L.; Schöller, M.; Graser, U.; Jaffe, W.; Lopez, B. Bibcode: 2016SPIE.9907E..0CA Altcode: MATISSE (Multi AperTure mid-Infrared SpectroScopic Experiment) is the spectro-interferometer for the VLTI of the European Southern Observatory, operating in near and mid-infrared, and combining up to four beams from the unit or the auxiliary telescopes. MATISSE will offer new breakthroughs in the study of circumstellar environments by allowing the multispectral mapping of the material distribution, the gas and essentially the dust. The instrument consists in a warm optical system (WOP) accepting four optical beams and relaying them after a dichroic splitting (for the L and M- and N- spectral bands) to cold optical benches (COB) located in two separate cryostats. The Observatoire de la Côte d'Azur is in charge of the WOP providing the spectral band separation, optical path equalization and modulation, pupil positioning, beam anamorphosis, beam commutation, and calibration. NOVA-ASTRON is in charge of the COB providing the functions of beam selection, reduction of thermal background emission, spatial filtering, pupil transfer, photometry and interferometry splitting, additional beam anamorphosis, spectral filtering, polarization selection, image dispersion, and image combination. The Max Planck Institut für Radio Astronomie is in charge of the operation and performance validation of the two detectors, a HAWAII-2RG from Teledyne for the L- and M- bands and a Raytheon AQUARIUS for the N-band. Both detectors are provided by ESO. The Max Planck Institut für Astronomie is in charge of the electronics and the cryostats for which the requirements on space limitations and vibration stability resulted on very specific and stringent decisions on the design. The integration and test of the COB: the two cryogenic systems, including the cold benches and the detectors, have been conducted at MPIA in parallel with the integration of the WOP at OCA. At the end of 2014, the complete instrument was integrated at OCA. Following this integration, a period of interface and alignment between the COB and the WOP took place resulting in the first interference fringes in the L-band during summer 2015 and the first interference fringes in the N-ban in March 2016. After a period of optimization of both the instrument reliability and the environmental working conditions, the test plan is presently being conducted in order to evaluate the complete performance of the instrument and its compliance with the high-level requirements. The present paper gives the first results of the alignment, integration and test phase of the MATISSE instrument. Title: An overview of the mid-infrared spectro-interferometer MATISSE: science, concept, and current status Authors: Matter, A.; Lopez, B.; Antonelli, P.; Lehmitz, M.; Bettonvil, F.; Beckmann, U.; Lagarde, S.; Jaffe, W.; Petrov, R.; Berio, P.; Millour, F.; Robbe-Dubois, S.; Glindemann, A.; Bristow, P.; Schoeller, M.; Lanz, T.; Henning, T.; Weigelt, G.; Heininger, M.; Morel, S.; Cruzalebes, P.; Meisenheimer, K.; Hofferbert, R.; Wolf, S.; Bresson, Y.; Agocs, T.; Allouche, F.; Augereau, J. -C.; Avila, G.; Bailet, C.; Behrend, J.; van Belle, G.; Berger, J. -P.; van Boekel, R.; Bourget, P.; Brast, R.; Clausse, J. -M.; Connot, C.; Conzelmann, R.; Csepany, G.; Danchi, W. C.; Delbo, M.; Dominik, C.; van Duin, A.; Elswijk, E.; Fantei, Y.; Finger, G.; Gabasch, A.; Gonté, F.; Graser, U.; Guitton, F.; Guniat, S.; De Haan, M.; Haguenauer, P.; Hanenburg, H.; Hofmann, K. -H.; Hogerheijde, M.; ter Horst, R.; Hron, J.; Hummel, C.; Isderda, J.; Ives, D.; Jakob, G.; Jasko, A.; Jolley, P.; Kiraly, S.; Kragt, J.; Kroener, T.; Kroes, G.; Kuindersma, S.; Labadie, L.; Laun, W.; Leinert, C.; Lizon, J. -L.; Lucuix, C.; Marcotto, A.; Martinache, F.; Martinot-Lagarde, G.; Mauclert, N.; Mehrgan, L.; Meilland, A.; Mellein, M.; Menardi, S.; Merand, A.; Neumann, U.; Nussbaum, E.; Ottogalli, S.; Palsa, R.; Panduro, J.; Pantin, E.; Percheron, I.; Phan Duc, T.; Pott, J. -U.; Pozna, E.; Roelfsema, R.; Rupprecht, G.; Schertl, D.; Schmidt, C.; Schuil, M.; Spang, A.; Stegmeier, J.; Tromp, N.; Vakili, F.; Vannier, M.; Wagner, K.; Venema, L.; Woillez, J. Bibcode: 2016SPIE.9907E..0AM Altcode: 2016arXiv160802350M MATISSE is the second-generation mid-infrared spectrograph and imager for the Very Large Telescope Interferometer (VLTI) at Paranal. This new interferometric instrument will allow significant advances by opening new avenues in various fundamental research fields: studying the planet-forming region of disks around young stellar objects, understanding the surface structures and mass loss phenomena affecting evolved stars, and probing the environments of black holes in active galactic nuclei. As a first breakthrough, MATISSE will enlarge the spectral domain of current optical interferometers by offering the L and M bands in addition to the N band. This will open a wide wavelength domain, ranging from 2.8 to 13 μm, exploring angular scales as small as 3 mas (L band) / 10 mas (N band). As a second breakthrough, MATISSE will allow mid-infrared imaging - closure-phase aperture-synthesis imaging - with up to four Unit Telescopes (UT) or Auxiliary Telescopes (AT) of the VLTI. Moreover, MATISSE will offer a spectral resolution range from R ∼ 30 to R ∼ 5000. Here, we present one of the main science objectives, the study of protoplanetary disks, that has driven the instrument design and motivated several VLTI upgrades (GRA4MAT and NAOMI). We introduce the physical concept of MATISSE including a description of the signal on the detectors and an evaluation of the expected performances. We also discuss the current status of the MATISSE instrument, which is entering its testing phase, and the foreseen schedule for the next two years that will lead to the first light at Paranal. Title: Status of the mid-infrared E-ELT imager and spectrograph METIS Authors: Brandl, Bernhard R.; Agócs, Tibor; Aitink-Kroes, Gabby; Bertram, Thomas; Bettonvil, Felix; van Boekel, Roy; Boulade, Olivier; Feldt, Markus; Glasse, Alistair; Glauser, Adrian; Güdel, Manuel; Hurtado, Norma; Jager, Rieks; Kenworthy, Matthew A.; Mach, Michael; Meisner, Jeff; Meyer, Michael; Pantin, Eric; Quanz, Sascha; Schmid, Hans Martin; Stuik, Remko; Veninga, Auke; Waelkens, Christoffel Bibcode: 2016SPIE.9908E..20B Altcode: METIS is one the first three instruments on the E-ELT. Apart from diffraction limited imaging, METIS will provide coronagraphy and medium resolution slit spectroscopy over the 3 - 19μm range, as well as high resolution (R 100,000) integral field spectroscopy from 2.9 - 5.3μm, including a mode with extended instantaneous wavelength coverage. The unique combination of these observing capabilities, makes METIS the ideal instrument for the study of circumstellar disks and exoplanets, among many other science areas. In this paper we provide an update of the relevant science drivers, the METIS observing modes, the status of the simulator and the data analysis. We discuss the preliminary design of the optical system, which is driven by the need to calibrate observations at thermal IR wavelengths on a six-mirror ELT. We present the expected adaptive optics performance and the measures taken to enable high contrast imaging. We describe the opto-mechanical system, the location of METIS on the Nasmyth instrument platform, and conclude with an update on critical subsystem components, such as the immersed grating and the focal plane detectors. In summary, the work on METIS has taken off well and is on track for first light in 2025. Title: MeerLICHT and BlackGEM: custom-built telescopes to detect faint optical transients Authors: Bloemen, Steven; Groot, Paul; Woudt, Patrick; Klein Wolt, Marc; McBride, Vanessa; Nelemans, Gijs; Körding, Elmar; Pretorius, Margaretha L.; Roelfsema, Ronald; Bettonvil, Felix; Balster, Harry; Bakker, Roy; Dolron, Peter; van Elteren, Arjen; Elswijk, Eddy; Engels, Arno; Fender, Rob; Fokker, Marc; de Haan, Menno; Hagoort, Klaas; de Hoog, Jasper; ter Horst, Rik; van der Kevie, Giel; Kozłowski, Stanisław; Kragt, Jan; Lech, Grzegorz; Le Poole, Rudolf; Lesman, Dirk; Morren, Johan; Navarro, Ramon; Paalberends, Willem-Jelle; Paterson, Kerry; Pawłaszek, Rafal; Pessemier, Wim; Raskin, Gert; Rutten, Harrie; Scheers, Bart; Schuil, Menno; Sybilski, Piotr W. Bibcode: 2016SPIE.9906E..64B Altcode: We present the MeerLICHT and BlackGEM telescopes, which are wide-field optical telescopes that are currently being built to study transient phenomena, gravitational wave counterparts and variable stars. The telescopes have 65 cm primary mirrors and a 2.7 square degree field-of-view. The MeerLICHT and BlackGEM projects have different science goals, but will use identical telescopes. The first telescope, MeerLICHT, will be commissioned at Sutherland (South Africa) in the first quarter of 2017. It will co-point with MeerKAT to collect optical data commensurate with the radio observations. After careful analysis of MeerLICHT's performance, three telescopes of the same type will be commissioned in La Silla (Chile) in 2018 to form phase I of the BlackGEM array. BlackGEM aims at detecting and characterizing optical counterparts of gravitational wave events detected by Advanced LIGO and Virgo. In this contribution we present an overview of the science goals, the design and the status of the two projects. Title: FAME: freeform active mirror experiment Authors: Aitink-Kroes, Gabby; Agócs, Tibor; Miller, Chris; Black, Martin; Farkas, Szigfrid; Lemared, Sabri; Bettonvil, Felix; Montgomery, David; Marcos, Michel; Jaskó, Attila; van Duffelen, Farian; Challita, Zalpha; Fok, Sandy; Kiaeerad, Fatemeh; Hugot, Emmanuel; Schnetler, Hermine; Venema, Lars Bibcode: 2016SPIE.9912E..1IA Altcode: FAME is a four-year project and part of the OPTICON/FP7 program that is aimed at providing a breakthrough component for future compact, wide field, high resolution imagers or spectrographs, based on both Freeform technology, and the flexibility and versatility of active systems. Due to the opening of a new parameter space in optical design, Freeform Optics are a revolution in imaging systems for a broad range of applications from high tech cameras to astronomy, via earth observation systems, drones and defense. Freeform mirrors are defined by a non-rotational symmetry of the surface shape, and the fact that the surface shape cannot be simply described by conicoids extensions, or off-axis conicoids. An extreme freeform surface is a significantly challenging optical surface, especially for UV/VIS/NIR diffraction limited instruments. The aim of the FAME effort is to use an extreme freeform mirror with standard optics in order to propose an integrated system solution for use in future instruments. The work done so far concentrated on identification of compact, fast, widefield optical designs working in the visible, with diffraction limited performance; optimization of the number of required actuators and their layout; the design of an active array to manipulate the face sheet, as well as the actuator design. In this paper we present the status of the demonstrator development, with focus on the different building blocks: an extreme freeform thin face sheet, the active array, a highly controllable thermal actuator array, and the metrology and control system. Title: Development and final design of FAME active array Authors: Farkas, Szigfrid; Agócs, Tibor; Aitink-Kroes, Gabby; Bettonvil, Felix; Black, Martin; Hugot, Emmanuel; Jaskó, Attila; Miller, Chris; Schnetler, Hermine; van Duffelen, Farian; Venema, Lars Bibcode: 2016SPIE.9912E..09F Altcode: FAME (Freeform Active Mirror Experiment - part of the FP7 OPTICON/FP7 development programme) intends to demonstrate the huge potential of active mirrors and freeform optical surfaces. Freeform active surfaces can help to address the new challenges of next generation astronomical instruments, which are bigger, more complex and have tighter specifications than their predecessors. The FAME design consists of a pre-formed, deformable thin mirror sheet with an active support system. The thin face sheet provides a close to final surface shape with very high surface quality. The active array provides the support, and through actuation, the control to achieve final surface shape accuracy. In this paper the development path, trade-offs and demonstrator design of the FAME active array is presented. The key step in the development process of the active array is the design of the mechanical structure and especially the optimization of the actuation node positions, where the actuator force is transmitted to the thin mirror sheet. This is crucial for the final performance of the mirror where the aim is to achieve an accurate surface shape, with low residual (high order) errors using the minimum number of actuators. These activities are based on the coupling of optical and mechanical engineering, using analytical and numerical methods, which results in an active array with optimized node positions and surface shape. Title: The BlackGEM array in search of black hole mergers: integrated performance modelling Authors: Roelfsema, Ronald; Klein Wolt, Marc; Bloemen, Steven; Groot, Paul; Bettonvil, Felix; Balster, Harry; Dolron, Peter; van Elteren, Arjen; Engels, Arno; de Haan, Menno; ter Horst, Rik; Kragt, Jan; Navarro, Ramon; Nelemans, Gijs; Paalberends, Willem Jelle; Pal, Sari; Raskin, Gert; Rutten, Harrie; Scheers, Bart; Schuil, Menno; Sybilski, Piotr Bibcode: 2016SPIE10012E..06R Altcode: The Radboud University Nijmegen in collaboration with the NOVA Optical Infrared Instrumentation group at ASTRON is currently leading the development and realization of the BlackGEM observing facility. The BlackGEM science team aims to be the first to catch the optical counterpart of a gravitational wave event. The BlackGEM project will put an array of three medium-sized optical telescopes at the La Silla site of the European Southern Observatory in Chile. It is uniquely equipped to achieve a combination of wide-field and high sensitivity through its array-like approach. Each BlackGEM unit telescope is a modified Dall-Kirkham-type telescope consisting of a 65cm primary mirror, a 21cm spherical secondary mirror and a triplet corrector lens. The spatial resolution on the sky will be 0.56 asec/pixel and the total field-of-view per telescope is 2.7 square degrees. The main requirement is to achieve a 5-sigma sensitivity of 23rd magnitude within a 5-minute exposure under 15 m/s wind gust conditions. This demands a very stable optical system with tight control of all the error contributions. This has been realized with a spreadsheet based integrated instrument model. The model contains all relevant telescope instrument parameters and environmental conditions. The spreadsheet is partly used for performance calculations and partly used to combine and integrate the output from several other sources. The spreadsheet model calculates the overall performance based on an Exposure Time Calculator using the Noise Equivalent Area metric (NEA). The NEA is further budgeted over 7 main High Level Requirements. The spreadsheet model is coupled to 1) a ZEMAX telescope optical model 2) a telescope FEM analysis to predict the optomechanical response under various gravity, temperature and wind load conditions, 3) a Matlab Simulink thermal model to predict the transient temperature behaviour of the most important telescope elements and 4) a Matlab Simulink control model to predict the performance of the active M2 mirror. All outputs are collected in a system performance budget that readily shows the compliance with the main High Level Requirements. Title: Foreword Authors: Bettonvil, F. Bibcode: 2016pimo.conf....6B Altcode: No abstract at ADS Title: Accurate Geminid velocities with CHIPOlAtA Authors: Bettonvil, F. Bibcode: 2016pimo.conf...31B Altcode: For several years, the high-resolution photographic camera CHIPOlAtA has been used to acquire precise orbits for Geminid and Perseid meteor shower members. In this paper I analyze the first set of data obtained during the Geminids 2014. Title: Program of the 35th International Meteor Conference, Egmond , 2 - 5 June, 2016 Authors: Bettonvil, F. Bibcode: 2016pimo.conf...13B Altcode: No abstract at ADS Title: High resolution orbits of Perseids and Geminids with CHIPOlAtA Authors: Bettonvil, F. Bibcode: 2015pimo.conf...78B Altcode: This paper focuses on the first results of the high-resolution camera project CHIPOlAtA that aims at measuring velocity with high accuracy, based on a setup with a fast liquid crystal optical chopper. So far three campaigns were carried out during the Perseid and Geminid maxima. The preliminary results, data reduction, a sensitivity analysis and the development of a data reduction pipeline are discussed. Title: HHEBBES! All sky camera system: status update Authors: Bettonvil, F. Bibcode: 2015pimo.conf..138B Altcode: A status update is given of the HHEBBES! All sky camera system. HHEBBES!, an automatic camera for capturing bright meteor trails, is based on a DSLR camera and a Liquid Crystal chopper for measuring the angular velocity. Purpose of the system is to a) recover meteorites; b) identify origin/parental bodies. In 2015, two new cameras were rolled out: BINGO! -alike HHEBBES! also in The Netherlands-, and POgLED, in Serbia. BINGO! is a first camera equipped with a longer focal length fisheye lens, to further increase the accuracy. Several minor improvements have been done and the data reduction pipeline was used for processing two prominent Dutch fireballs. Title: De fraaie vuurbol van 19 oktober 2014 Authors: Miskotte, Koen; Langbroek, Marco; Bettonvil, Felix; Johannink, Carl Bibcode: 2014eRad...10...59M Altcode: Overview of all available observations and analyzes of the fireball of October 19, 2014. Title: An Overview of the MATISSE Instrument — Science, Concept and Current Status Authors: Lopez, B.; Lagarde, S.; Jaffe, W.; Petrov, R.; Schöller, M.; Antonelli, P.; Beckmann, U.; Berio, P.; Bettonvil, F.; Glindemann, A.; Gonzalez, J. -C.; Graser, U.; Hofmann, K. -H.; Millour, F.; Robbe-Dubois, S.; Venema, L.; Wolf, S.; Henning, T.; Lanz, T.; Weigelt, G.; Agocs, T.; Bailet, C.; Bresson, Y.; Bristow, P.; Dugué, M.; Heininger, M.; Kroes, G.; Laun, W.; Lehmitz, M.; Neumann, U.; Augereau, J. -C.; Avila, G.; Behrend, J.; van Belle, G.; Berger, J. -P.; van Boekel, R.; Bonhomme, S.; Bourget, P.; Brast, R.; Clausse, J. -M.; Connot, C.; Conzelmann, R.; Cruzalèbes, P.; Csepany, G.; Danchi, W.; Delbo, M.; Delplancke, F.; Dominik, C.; van Duin, A.; Elswijk, E.; Fantei, Y.; Finger, G.; Gabasch, A.; Gay, J.; Girard, P.; Girault, V.; Gitton, P.; Glazenborg, A.; Gonté, F.; Guitton, F.; Guniat, S.; De Haan, M.; Haguenauer, P.; Hanenburg, H.; Hogerheijde, M.; ter Horst, R.; Hron, J.; Hugues, Y.; Hummel, C.; Idserda, J.; Ives, D.; Jakob, G.; Jasko, A.; Jolley, P.; Kiraly, S.; Köhler, R.; Kragt, J.; Kroener, T.; Kuindersma, S.; Labadie, L.; Leinert, C.; Le Poole, R.; Lizon, J. -L.; Lucuix, C.; Marcotto, A.; Martinache, F.; Martinot-Lagarde, G.; Mathar, R.; Matter, A.; Mauclert, N.; Mehrgan, L.; Meilland, A.; Meisenheimer, K.; Meisner, J.; Mellein, M.; Menardi, S.; Menut, J. -L.; Merand, A.; Morel, S.; Mosoni, L.; Navarro, R.; Nussbaum, E.; Ottogalli, S.; Palsa, R.; Panduro, J.; Pantin, E.; Parra, T.; Percheron, I.; Duc, T. P.; Pott, J. -U.; Pozna, E.; Przygodda, F.; Rabbia, Y.; Richichi, A.; Rigal, F.; Roelfsema, R.; Rupprecht, G.; Schertl, D.; Schmidt, C.; Schuhler, N.; Schuil, M.; Spang, A.; Stegmeier, J.; Thiam, L.; Tromp, N.; Vakili, F.; Vannier, M.; Wagner, K.; Woillez, J. Bibcode: 2014Msngr.157....5L Altcode: MATISSE, a second generation Very Large Telescope Interferometer (VLTI) instrument, is a combined imager and spectrograph for interferometry in the 3-5 μm region (L- and M-bands) and the 8-13 μm window (N-band). MATISSE builds on the experience gained with the VLTI's first generation instruments. It employs multi-axial beam combination while also providing wavelength differential visibility and phase, and closure-phase aperture-synthesis imaging at a range of spectral resolutions. MATISSE is designed for a broad range of science goals, and its potential for studies of the discs around young stars and active galactic nuclei are highlighted. The instrument concept and operating modes are described; construction is in progress towards installation at the VLTI in 2016. Title: Complexity in the MATISSE cold optics: a risk or a tool? Authors: Tromp, Niels; Bettonvil, Felix; Aitink-Kroes, Gabby; Agócs, Tibor; Navarro, Ramón Bibcode: 2014SPIE.9150E..1DT Altcode: MATISSE (Multi AperTure mid-Infrared SpectroScopic Experiment) will be a mid-infrared spectro-interferometer combining the beams of up to four telescopes of the European Southern Observatory Very Large Telescope Interferometer (ESO VLTI), providing phase closure and image reconstruction. MATISSE will produce interferometric spectra in the LM and N band (2.8 to 13 micron). Building the cryogenic interferometer section of an instrument like MATISSE is inherently complex. During the preliminary design phase it became clear that this inherent complexity should not be seen as a hurdle but rather a tool; to keep project risks low it is vital to first comprehend the complexity and second to distribute these complexities to areas of expertise, i.e. fields of low risk. With this approach one prevents the typical reaction of either steering away from complexity or digging narrow and deep to find only a local solution. Complexity can be used to achieve the project goals with a reduced overall project risk. For example two alternative options: either a complex single structure with limited interfaces or an assembly of many simpler parts with, in total, much more interfaces. Although simpler in approach, the latter would be a burden on the overall tolerance chain, assembly procedures, logistics & overall cost, culminating in a higher overall risk to the project; the unintended shift of complexity and risk to a later project phase. In addition, this fragmentation would reduce the overall grip on the project and would make it more difficult to identify showstoppers early on. And solving these becomes exponentially more difficult in later project stages. The integral multidisciplinary approach, earlier discussed in "MATISSE cold optics opto-mechanical design" Proc. SPIE 7734, 77341S (2010), enables optimal distribution of complexity and lowering of overall project risk. This current proceeding presents the way in which the high level of opto-mechanical complexity and risks were distributed and dealt with during the MATISSE Cold Optics Bench instrument development. Title: Remote and automatic small-scale observatories: experience with an all-sky fireball patrol camera Authors: Bettonvil, Felix C. M. Bibcode: 2014SPIE.9147E..3UB Altcode: This paper describes the design of a remote, automatic all-sky camera for capturing bright meteor trails based on a DSLR camera combined with Liquid Crystal shutter technology for angular velocity measurement. Design, performance and first results are discussed, as well the up scaling towards a large autonomous network for accurate fireball orbit determination and meteorite recovery. Title: MATISSE status report and science forecast Authors: Lopez, B.; Lagarde, S.; Jaffe, W.; Petrov, R.; Schöller, M.; Antonelli, P.; Beckman, U.; Bério, Ph.; Bettonvil, F.; Graser, U.; Millour, F.; Robbe-Dubois, S.; Venema, L.; Wolf, S.; Bristow, P.; Glindemann, A.; Gonzalez, J. -C.; Lanz, Th.; Henning, T.; Weigelt, G.; Agócs, T.; Augereau, J. -C.; Ávila, G.; Bailet, C.; Behrend, J.; Berger, J. -P.; von Boekel, Roy; Bonhomme, S.; Bourget, P.; Brast, R.; Bresson, Y.; Clausse, J. M.; Chesneau, O.; Csépány, G.; Connot, C.; Crida, A.; Danchi, W. C.; Delbo, M.; Delplancke, F.; Dominik, C.; Dugué, M.; Elswijk, E.; Fanteï, Y.; Finger, G.; Gabasch, A.; Girard, P.; Girault, V.; Gitton, P.; Glazenborg, A.; Gonté, F.; Guitton, F.; Guniat, S.; De Haan, M.; Haguenauer, P.; Hanenburg, H.; Heininger, M.; Hofmann, K. -H.; Hogerheijde, M.; ter Horst, R.; Hron, J.; Hughes, Y.; Ives, D.; Jakob, G.; Jaskó, A.; Jolley, P.; Kragt, J.; Köhler, R.; Kroener, T.; Kroes, G.; Labadie, L.; Laun, W.; Lehmitz, M.; Leinert, Ch.; Lizon, J. L.; Lucuix, Ch.; Marcotto, A.; Martinache, F.; Matter, A.; Martinot-Lagarde, G.; Mauclert, N.; Mehrgan, L.; Meilland, A.; Mellein, M.; Ménardi, S.; Menut, J. L.; Meisenheimer, K.; Morel, S.; Mosoni, L.; Navarro, R.; Neumann, U.; Nussbaum, E.; Ottogalli, S.; Palsa, R.; Panduro, J.; Pantin, E.; Percheron, I.; Duc, T. Phan; Pott, J. -U.; Pozna, Eszter; Przygodda, F.; Richichi, A.; Rigal, F.; Rupprecht, G.; Schertl, D.; Stegmeier, J.; Thiam, L.; Tromp, N.; Vannier, M.; Vakili, F.; van Belle, G.; Wagner, K.; Woillez, J. Bibcode: 2014SPIE.9146E..0ML Altcode: MATISSE is the mid-infrared spectrograph and imager for the Very Large Telescope Interferometer (VLTI) at Paranal. This second generation interferometry instrument will open new avenues in the exploration of our Universe. Mid-infrared interferometry with MATISSE will allow significant advances in various fundamental research fields: studies of disks around young stellar objects where planets form and evolve, surface structures and mass loss of stars in late evolutionary stages, and the environments of black holes in active galactic nuclei. MATISSE is a unique instrument. As a first breakthrough it will enlarge the spectral domain used by optical interferometry by offering the L & M bands in addition to the N band, opening a wide wavelength domain, ranging from 2.8 to 13 μm on angular scales of 3 mas (L/M band) / 10 mas (N band). As a second breakthrough, it will allow mid-infrared imaging - closure-phase aperture-synthesis imaging - with up to four Unit Telescopes (UT) or Auxiliary Telescopes (AT) of the VLTI. MATISSE will offer various ranges of spectral resolution between R~30 to ~5000. In this article, we present some of the main science objectives that have driven the instrument design. We introduce the physical concept of MATISSE including a description of the signal on the detectors and an evaluation of the expected performance and discuss the project status. The operations concept will be detailed in a more specific future article, illustrating the observing templates operating the instrument, the data reduction and analysis, and the image reconstruction software. Title: MASCARA: opto-mechanical design and integration Authors: Spronck, Julien F. P.; Lesage, Anna-Léa.; Stuik, Remko; Bettonvil, Felix; Snellen, Ignas A. G. Bibcode: 2014SPIE.9147E..56S Altcode: MASCARA, the Multi-site All-Sky CAmeRA, consists of several fully-automated stations. Its goal is to find exoplanets transiting the brightest stars, in the mV = 4 to 8 magnitude range. Each station contains five wide- angle cameras monitoring the near-entire sky at each location. The five cameras are located in a temperature- controlled enclosure and look at the sky through five windows. A housing with a moving roof protects MASCARA from the environment. Here, we present the opto-mechanical design of the first MASCARA station. Title: Realization and performance of cryogenic selection mechanisms Authors: Aitink-Kroes, Gabby; Bettonvil, Felix; Kragt, Jan; Elswijk, Eddy; Tromp, Niels Bibcode: 2014SPIE.9151E..0FA Altcode: Within Infra-Red large wavelength bandwidth instruments the use of mechanisms for selection of observation modes, filters, dispersing elements, pinholes or slits is inevitable. The cryogenic operating environment poses several challenges to these cryogenic mechanisms; like differential thermal shrinkage, physical property change of materials, limited use of lubrication, high feature density, limited space etc. MATISSE the mid-infrared interferometric spectrograph and imager for ESO's VLT interferometer (VLTI) at Paranal in Chile coherently combines the light from 4 telescopes. Within the Cold Optics Bench (COB) of MATISSE two concepts of selection mechanisms can be distinguished based on the same design principles: linear selection mechanisms (sliders) and rotating selection mechanisms (wheels).Both sliders and wheels are used at a temperature of 38 Kelvin. The selection mechanisms have to provide high accuracy and repeatability. The sliders/wheels have integrated tracks that run on small, accurately located, spring loaded precision bearings. Special indents are used for selection of the slider/wheel position. For maximum accuracy/repeatability the guiding/selection system is separated from the actuation in this case a cryogenic actuator inside the cryostat. The paper discusses the detailed design of the mechanisms and the final realization for the MATISSE COB. Limited lifetime and performance tests determine accuracy, warm and cold and the reliability/wear during life of the instrument. The test results and further improvements to the mechanisms are discussed. Title: Manufacturing, integration, and test results of the MATISSE cold optics bench Authors: Bettonvil, Felix C. M.; Kroes, G.; Agoćs, T.; van Duin, A.; Elswijk, E.; de Haan, M.; ter Horst, R.; Kragt, J.; Kuindersma, J.; Navarro, R.; Roelfsema, R.; Schuil, M.; Tromp, T.; Venema, L.; van Kessel, F.; Jaskó, A. Bibcode: 2014SPIE.9147E..7QB Altcode: MATISSE is the second-generation mid-infrared interferometric spectrograph and imager for ESO's Very Large Telescope Interferometer (VLTI). NOVA-ASTRON is responsible for the Cold Optics Bench (COB), representing the last part of the optics train where the four beams are re-arranged, spectrally dispersed and combined. The COB consist of two sister units, one for the LM-band, one for the N-band, which were successively completed at NOVA-ASTRON in autumn 2013 and spring 2014. The LM-band COB is under cryogenic test in its cryostat at MPIA/Heidelberg; the N-band COB finished cryogenic tests and has been installed at OCA/Nice for integration together with the Warm Optics. This paper focuses on the manufacturing, integration and test results of the COBs, and gives an overview of the current status. Title: MASCARA: the multi-site all-sky CAameRA: concept and first results Authors: Lesage, A. -L.; Spronck, J. F. P.; Stuik, R.; Bettonvil, F.; Pollaco, D.; Snellen, I. A. G. Bibcode: 2014SPIE.9145E..14L Altcode: MASCARA, the Multi-site All-Sky CAmeRA, will consist of several fully-automated stations distributed across the globe. Its goal is to find exoplanets transiting the brightest stars, in the mV = 4 to 8 magnitude range, currently probed neither by space- nor by ground-based surveys. The nearby transiting planet systems that MASCARA is expected to discover will be key targets for future detailed planet atmosphere observations. The target population for MASCARA consists mostly of hot Jupiters. The main requirement set on MASCARA to detect these planets around stars down to magnitude 8 is to reach a minimum Signal-to-Noise Ratio of 100 within one hour of observation. Each MASCARA station consists of five low-noise off-the-shelf full-frame CCD cameras, fitted with standard Canon 24 mm , f/1.4 lenses, monitoring the near-entire sky down to magnitude 8 at that location. Measurements have demonstrated that the required Signal-to-Noise Ratio of 100, can be achieved in less than thirty minutes. MASCARA aims at deploying several stations world-wide to provide a nearly continuous coverage of the dark sky, at sub-minute cadence. While at the faint end MASCARA is limited mainly by photon noise, at the bright end scintillation and red noise become the limiting factors. Instrumental noise sources are reduced by placing the cameras in a fixed orientation and in a temperature controlled environment. By defocusing and allowing stars to drift over the detector, the impact of pixel-to-pixel variations on the photometry are minimized, while taking exposures at fixed sidereal times allows accurate cross-calibration of consecutive nights. The exposure time of 6.4 seconds gives rise to a high data acquisition rate of a MASCARA station, around 500GB per night. In order to minimize data transport and data storage requirements, the raw images are reduced to produce accurate light curves in nearly real time. The first MASCARA station will be integrated on La Palma during the summer of 2014. MASCARA test data were taken in July 2013 with one camera targeting the transiting exoplanet HD 189733b. Its brightness of mV = 7:7 is close to the faint end of the MASCARA magnitude range. The 5 - σ detection of the 2.8% deep transit with a 5-minute binning of the data confirms that we will be able to detect 1% transit at the faint end within one hour. Title: Finding planets transiting the brightest stars with MASCARA Authors: Spronck, J. F. P.; Lesage, A. -L.; Stuik, R.; Bettonvil, F.; Snellen, I. A. G. Bibcode: 2014ebi..confP3.63S Altcode: MASCARA, the Multi-site All-sky CAmeRA, is an instrument concept that will consist of several stations distributed across the globe, with each station containing a few low-cost wide-angle cameras to monitor the near-entire sky at each location. Once all stations have been deployed, MASCARA will provide a nearly 24-hour coverage of the complete dark sky, down to magnitude 8, at sub-minute cadence. Its purpose is to find exoplanets transiting the brightest stars (in the V=4-8 magnitude range) - currently not probed by space- or ground-based surveys. The nearby transiting planet systems that MASCARA will discover will be the key targets for detailed planet atmosphere observations. Here, we present the final design of MASCARA as well as some preliminary results showing that the required photometric precision of 1% per hour is achieved for the faintest stars in our magnitude range. Title: CAMS BeNeLux Authors: Bettonvil, Felix; Johannink, Carl; Breukers, Martin Bibcode: 2014pim4.conf...55B Altcode: This paper gives an overview of the current status of the BeNeLux CAMS video meteor network as operated in the Netherlands and Belgium, and part of the NASA funded automated meteor video surveillance project CAMS. Title: Geminids 2012 - a spectacular show from Oman Authors: Weiland, Thomas; Bettonvil, Felix Bibcode: 2014pim4.conf...89W Altcode: The Geminids are the most reliable prominent meteor shower currently visible. They can be observed from the whole northern hemisphere and even low southern latitudes as well. Nevertheless, as the weather is often unfavourable in Central Europe during December, a six-day-long visual observing campaign was carried out from Oman in 2012. There observing conditions were nearly perfect, especially in the Rub al-Khali desert in the western part of the country. As a consequence, we managed to record more than 1800 Geminids within almost 45 hours of effective observing time. An impression of the campaign together with a summary of the results is given. Title: High resolution photographic imaging Authors: Bettonvil, Felix Bibcode: 2014pim4.conf...30B Altcode: A high-resolution camera is described, based on DSLR technology and long focal length lens together with a 200 cycles/sec optical shutter, with the aim to collect higher accuracy orbital elements. The paper describes the design considerations, test setup, and analyses and discusses the first results. Title: CILBO - Lessons learned from a double-station meteor camera setup in the Canary Islands Authors: Koschny, Detlef; Mc Auliffe, Jonathan; Drolshagen, Esther; Bettonvil, Felix; Licandro, Javier; van der Luijt, Cornelis; Ott, Theresa; Smit, Hans; Svedhem, Hakan; Witasse, Olivier; Zender, Joe Bibcode: 2014pim4.conf...10K Altcode: We have been operating a double-station meteor camera setup and have collected more than 12 months of simultaneous observations until mid-2014. First science is being produced. In this paper we report on the lessons learned and provide information on what went well and what did not. The intention is to help other teams considering setting up similar systems to avoid the same issues. Title: The Benelux CAMS Network—status July 2013 Authors: Roggemans, Paul; Betlem, Hans; Bettonvil, Felix; Biets, Jean-Marie; Breukers, Martin; Haas, Robert; Jobse, Klaas; Johannink, Carl; Langbroek, Marco; Miskotte, Koen; Neels, Piet; Nijland, Jos; ter Kuile, Casper Bibcode: 2014pim3.conf..173R Altcode: A network of CAMS, "Cameras for All-sky Meteor Surveillance", is being built up in the Benelux1 since early 2012. If weather permits, the network has curently 18 CAMS active at 10 observing posts. More than 2000 accurate meteor orbits were recorded so far. Title: CILBO—Two years operation of a double-station meteor camera set-up in the Canary Islands Authors: Koschny, Detlef; McAuliffe, Jonathan; Bettonvil, Felix; Licandro, Javier; van der Luijt, Cornelis; Smit, Hans; Svedhem, Høakan; Witasse, Olivier; Zender, Joe Bibcode: 2014pim3.conf..166K Altcode: Since the Summer of 2011, the Meteor Research Group of the Research and Scientific Support Department of ESA has been operating a meteor camera on Tenerife. At the end of 2011, a second station on La Palma was added to the set-up, completing the double-station setup CILBO (Canary Island Long-Baseline Observatory). Here, we give an overview of the data obtained from 1 January to 31 August 2013. The system's availability is just below 70%. Title: EST: the largest and most sensitive spectropolarimeter Authors: Collados, M.; Bettonvil, F.; Cavaller, L.; Ermolli, I.; Gelly, B.; Pérez, A. : Socas-Navarro, H.; Soltau, D.; Volkmer, R.; EST Team Bibcode: 2013hsa7.conf..808C Altcode: Magnetic field plays a crucial role to understand most phenomena happening in the solar atmosphere. Sunspots, flares, prominences, coronal mass ejections are well known examples of its interaction with the solar plasma. To study the properties of this interaction, one needs to analyze the imprint it leaves in the radiation through the polarization induced in spectral lines, via the Zeeman and Hanle effects. Outside sunspots, the polarization degree of the emitted light is usually well below one part in one thousand, which requires sophisticated techniques to measure it accurately. To further complicate the situation, telescopes use mirrors and these introduce undesired polarization which is two or three orders of magnitude larger than that caused by the magnetic field of solar structures. For this reason, present telescopes doing polarimetry require an adequate modelling to correct the measured data from these spurious effects. In addition, most of the magnetic field interactions with the plasma take place at small scales. The best achievable angular resolution is mandatory to adequately study magnetic phenomena. The European solar Telescope (EST) has been defined to overcome these difficulties. Here, some aspects of the design are described. Title: MASCARA: The Multi-site All-Sky CAmeRA Authors: Snellen, Inas; Stuik, Remko; Otten, Gilles; Bettonvil, Felix; Navarro, Ramon; Kenworthy, Matthew; de Mooij, Ernst; ter Horst, Rik; Le Poole, Rudolf; Lesage, Anna-Lea; Spronck, Julien Bibcode: 2013EPJWC..4703008S Altcode: The Multi-site All-Sky CAmeRA, MASCARA, is an instrument currently in the design phase, that is aimed to find the brightest transiting planet systems in the sky. It will consist of several stations across the globe, each monitoring the near-entire sky using a battery of CCD-detectors plus wide-field lenses, targeting stars in the V = 4 - 8 magnitude range. MASCARA will be able to detect individual transits from Jupiter-size planets over this whole magnitude range, while smaller planets will be found by co-adding transit events. We expect to discover up to a dozen bright transit systems in this way. These will be extremely valuable for atmospheric follow-up studies. Title: Kees Zwaan, open principle, future of high-resolution solar telescopes Authors: Hammerschlag, R. H.; Bettonvil, F. C. M. Bibcode: 2013ASPC..470..381H Altcode: It was around the 1970s that during site-test campaigns masts were erected up till 30 m height with sensors at several heights for the measurement of temperature fluctuations. Kees Zwaan discovered that the fluctuations decrease drastically at heights from about 15 m and upward when there is some wind. The conclusion from this experience was the open telescope principle: a telescope completely free in the air 15 m or more above the ground. The Dutch Open Telescope (DOT) was the pioneering demonstrator of the open-telescope technology. Now that larger high-resolution telescopes come in view, it is time to analyze again the principle: the essentials for proper working of the open principle and the design consequences for the new generation of high-resolution solar telescopes. Title: Utrecht and the European Solar Telescope Authors: Bettonvil, F. C. M.; EST Team Bibcode: 2013ASPC..470..389B Altcode: In 2008, in the quest towards large solar facilities, a pan-European project was started to study a 4-m European Solar Telescope (EST). As one of the major partners, Utrecht played a significant role in the design, in particular in relation to the intended open design, its enclosure, telescope mechanics as well its polarimetric properties. Mid-2011 the work did result in an innovative conceptual design for EST. Title: Digital all-sky cameras VII: Putting the camera into operation Authors: Bettonvil, Felix Bibcode: 2013pimo.conf...34B Altcode: This seventh paper about the development of a digital all-sky camera, built around a Canon EOS 350D, Sigma 4.5mm f/2.8 EX DC fisheye lens and liquid crystal optical chopper, describes the constructed system and the first half year of operation. Title: The European Solar Telescope Authors: Collados, M.; Bettonvil, F.; Cavaller, L.; Ermolli, I.; Gelly, B.; Pérez, A.; Socas-Navarro, H.; Soltau, D.; Volkmer, R.; EST Team Bibcode: 2013MmSAI..84..379C Altcode: The European Solar Telescope (EST) is a project to design, build and operate an European Solar 4-meter class telescope to be located in the Canary Islands, with the participation of institutions from fifteen European countries gathered around the consortium EAST (European Association for Solar Telescopes). The project main objective up to the present has been the development of the conceptual design study (DS) of a large aperture Solar Telescope. The study has demonstrated the scientific, technical and financial feasibility of EST. The DS has been possible thanks to the co-financing allocated specifically by the EU and the combined efforts of all the participant institutions. Different existing alternatives have been analysed for all telescope systems and subsystems, and decisions have been taken on the ones that are most compatible with the scientific goals and the technical strategies. The present status of some subsystems is reviewed in this paper. Title: The 2011 Eta-Aquariids observing campaign from La Palma Authors: Bettonvil, Felix; Weiland, Thomas Bibcode: 2013pimo.conf..115B Altcode: Because the Eta-Aquariids, the most prominent stream for Southern Hemisphere observers, are difficult to watch from mid-northern latitudes, a week-long visual observing campaign was carried out in May 2011 from La Palma, Canary Islands, Spain. There, on the grounds of the Observatorio del Roque de Los Muchachos (ORM), at an altitude of more than 2000 m above sea level, observing conditions were nearly perfect. As a consequence, we managed to record more than 300 Eta-Aquariids in about 30 hours of effective observing time. An impression of the campaign together with a summary of the results is given. Title: Open-foldable domes with high-tension textile membranes: The GREGOR dome Authors: Hammerschlag, R. H.; Kommers, J. N.; Visser, S.; Bettonvil, F. C. M.; van Schie, A. G. M.; van Leverink, S. J.; Sliepen, G.; Jägers, A. P. L.; Schmidt, W.; Volkmer, R. Bibcode: 2012AN....333..830H Altcode: Double layers of high-tensioned textile membranes were applied to the completely open-foldable dome for the GREGOR telescope for the first time. Simultaneous climate measurements inside and outside the dome have proven the thermal-insulating capability of this double-layer construction. The GREGOR dome is the result of the continuation of the ESO research on open-foldable domes with textile structures, followed by the research for the DOT dome with high-tensioned textile membranes. It cleared the way to extreme stability required for astronomical practice on high mountain sites with heavy storms and ice formation. The storm Delta with 245 km/h 1-minute mean maximum at the location of the GREGOR caused no problems, nor did other storms afterwards. Opening and closing experiences up to wind speeds of 90 km/h were without problems. New technical developments were implemented and tested at the GREGOR dome, opening the way for application to much larger domes up to the 30 m diameter-class range. Title: The GREGOR dome, pathfinder for the EST dome Authors: Hammerschlag, Robert H.; Kommers, Johannes N.; Visser, Simon; Bettonvil, Felix C. M.; van Schie, Anton G. M.; van Leverink, Simon J.; Sliepen, Guus; Jägers, Aswin P. L. Bibcode: 2012SPIE.8450E..07H Altcode: The completely open-foldable dome of the GREGOR telescope is a further development of the DOT dome, respectively 9 and 7 meter in diameter. New technical developments are implemented and tested at the GREGOR dome, that are important for the design of the much larger dome for the EST, which will be 28 meter in diameter. The GREGOR dome is the first with more than one clamp working simultaneously for closing the dome and bringing the membranes on the required high tension for storm resistance. The storm Delta with 245 km/h 1-minute mean maximum at the location of the GREGOR gave no problems nor did the storms afterwards. Opening and closing experiences are up to wind speeds of 90 km/h without problems. Good observing circumstances never occur with higher wind speeds. A double layer of membranes is applied in the GREGOR construction whereas the DOT dome is equipped with a single layer. Simultaneous climate measurements inside and outside the dome have proven the thermal-insulation capability of this double-layer construction. The experiences with the GREGOR showed that the elongation by tensioning of the prestrained membrane material is much lower than originally expected. In the meantime, more strong and stiff membrane material is available and applied in the EST design. As a consequence, the clamps of the EST can have a relatively much shorter length and there is no need anymore for simultaneous operation of the clamps and the main actuators in low speed with help of a frequency inverter. The clamps can close after the main bow operation is finished, which simplifies the electrical control. Title: Large-field high-resolution mosaic movies Authors: Hammerschlag, Robert H.; Sliepen, Guus; Bettonvil, Felix C. M.; Jägers, Aswin P. L.; Sütterlin, Peter; Martin, Sara F. Bibcode: 2012SPIE.8444E..06H Altcode: Movies with fields-of-view larger than normal for high-resolution telescopes will give a better understanding of processes on the Sun, such as filament and active region developments and their possible interactions. New active regions can influence, by their emergence, their environment to the extent of possibly serving as an igniter of the eruption of a nearby filament. A method to create a large field-of-view is to join several fields-of-view into a mosaic. Fields are imaged quickly one after another using fast telescope-pointing. Such a pointing cycle has been automated at the Dutch Open Telescope (DOT), a high-resolution solar telescope located on the Canary Island La Palma. The observer can draw with the computer mouse the desired total field in the guider-telescope image of the whole Sun. The guider telescope is equipped with an H-alpha filter and electronic enhancement of contrast in the image for good visibility of filaments and prominences. The number and positions of the subfields are calculated automatically and represented by an array of bright points indicating the subfield centers inside the drawn rectangle of the total field on the computer screen with the whole-sun image. When the exposures start the telescope repeats automatically the sequence of subfields. Automatic production of flats is also programmed including defocusing and fast motion over the solar disk of the image field. For the first time mosaic movies were programmed from stored information on automated telescope motions from one field to the next. The mosaic movies fill the gap between whole-sun images with limited resolution of synoptic telescopes including space instruments and small-field high-cadence movies of high-resolution solar telescopes. Title: Ground-based search for the brightest transiting planets with the Multi-site All-Sky CAmeRA: MASCARA Authors: Snellen, Ignas A. G.; Stuik, Remko; Navarro, Ramon; Bettonvil, Felix; Kenworthy, Matthew; de Mooij, Ernst; Otten, Gilles; ter Horst, Rik; le Poole, Rudolf Bibcode: 2012SPIE.8444E..0IS Altcode: 2012arXiv1208.4116S The Multi-site All-sky CAmeRA MASCARA is an instrument concept consisting of several stations across the globe, with each station containing a battery of low-cost cameras to monitor the near-entire sky at each location. Once all stations have been installed, MASCARA will be able to provide a nearly 24-hr coverage of the complete dark sky, down to magnitude 8, at sub-minute cadence. Its purpose is to find the brightest transiting exoplanet systems, expected in the V=4-8 magnitude range - currently not probed by space- or ground-based surveys. The bright/nearby transiting planet systems, which MASCARA will discover, will be the key targets for detailed planet atmosphere observations. We present studies on the initial design of a MASCARA station, including the camera housing, domes, and computer equipment, and on the photometric stability of low-cost cameras showing that a precision of 0.3-1% per hour can be readily achieved. We plan to roll out the first MASCARA station before the end of 2013. A 5-station MASCARA can within two years discover up to a dozen of the brightest transiting planet systems in the sky. Title: MATISSE: concept, specifications, and performances Authors: Lagarde, S.; Robbe-Dubois, S.; Petrov, R. G.; Lopez, B.; Jaffe, W. J.; Venema, L.; Berio, Ph.; Antonelli, P.; Beckmann, U.; Bettonvil, F. C.; Graser, U.; Navarro, R.; Matter, A. Bibcode: 2012SPIE.8445E..2JL Altcode: MATISSE (Multi AperTure mid-Infrared SpectroScopic Experiment) is the future spectro-interferometer of the European Southern Observatory VLT operating in the spectral bands L, M and N, and combining four beams from the telescopes UTs or ATs. This paper describes the concept, the specifications and the expected performances of the instrument. The requirements have been established including transmission and contrast degradation budgets. An assessment of the performances is given in this paper taking into account the instrument and VLTI characteristics. Title: Perspective of imaging in the mid-infrared at the Very Large Telescope Interferometer Authors: Lopez, B.; Lagarde, S.; Antonelli, P.; Jaffe, W.; Petrov, R.; Venema, L.; Robbe-Dubois, Sylvie; Bettonvil, F.; Berio, P.; Navarro, R.; Graser, U.; Beckman, U.; Weigelt, G.; Vakili, F.; Henning, T.; Gonzales, J. -C.; Wolf, S.; Bailet, C.; Behrend, J.; Bresson, Y.; Chesneau, O.; Clausse, J. M.; Connot, C.; Dugué, M.; Fantei, Y.; Elswijk, E.; Hanenburg, H.; Hofmann, K. H.; Heininger, M.; ter Horst, R.; Hron, J.; Kragt, J.; Tromp, N.; Agocs, T.; Kroes, G.; Laun, W.; Leinert, Ch.; Lehmitz, M.; Matter, A.; Menut, J. L.; Millour, F.; Neumann, U.; Nussbaum, E.; Ottogalli, S.; Pott, J. -U.; Rigal, F.; Roussel, A.; Schertl, D.; Vannier, M.; Wagner, K.; Mellein, M.; Kroener, T.; Mauclert, N.; Girard, P.; Lagarde, G. M.; Mosoni, L.; Jasko, A.; Glindemann, A.; Phan Duc, T.; Finger, G.; Ives, D.; Jakob, G.; Percheron, I.; Avila, G.; Palsa, R.; Pozna, E.; Lizon, J. L.; Lucuix, Ch.; Menardi, S.; Haguenauer, P.; Gitton, P.; Morel, S.; Gonté, F.; Jolley, P.; Rupprecht, G.; Bourget, P.; Delplancke, F.; Mehrgan, L.; Stegmeier, J.; van Belle, G.; Richichi, A.; Moorwood, A. Bibcode: 2012SPIE.8445E..0RL Altcode: MATISSE is a mid-infrared spectro-interferometer combining the beams of up to four Unit Telescopes or Auxiliary Telescopes of the Very Large Telescope Interferometer (VLTI) of the European Southern Observatory. MATISSE will constitute an evolution of the two-beam interferometric instrument MIDI. New characteristics present in MATISSE will give access to the mapping and the distribution of the material, the gas and essentially the dust, in the circumstellar environments by using the mid-infrared band coverage extended to L, M and N spectral bands. The four beam combination of MATISSE provides an efficient uv-coverage: 6 visibility points are measured in one set and 4 closure phase relations which can provide aperture synthesis images in the mid-infrared spectral regime. We give an overview of the instrument including the expected performances and a view of the Science Case. We present how the instrument would be operated. The project involves the collaborations of several agencies and institutes: the Observatoire de la Côte d’Azur of Nice and the INSU-CNRS in Paris, the Max Planck Institut für Astronomie of Heidelberg; the University of Leiden and the NOVA-ASTRON Institute of Dwingeloo, the Max Planck Institut für Radioastronomie of Bonn, the Institut für Theoretische Physik und Astrophysik of Kiel, the Vienna University and the Konkoly Observatory. Title: Light Curves from a Permanent Meteor Camera Station in the Canary Islands Authors: Koschny, D.; Bettonvil, F.; v. d. Luijt, C.; Mc Auliffe, J.; Smit, H.; Svedhem, H.; Witasse, O.; Zender, J. Bibcode: 2012LPICo1667.6140K Altcode: This presentation will present first results of a permanent meteor double station setup in the Canary islands. In particular, it will focus on the measured meteor light curves. Title: Data handling and control of the European Solar Telescope Authors: Ermolli, I.; Bettonvil, F.; Cauzzi, G.; Cavaller, L.; Collados, M.; Di Marcantonio, P.; Grivel, C.; Paletou, F.; Romano, P.; Aboudarham, J.; Cirami, R.; Cosentino, R.; Giorgi, F.; Lafon, M.; Laforgue, D.; Reardon, K.; Sliepen, G. Bibcode: 2012MSAIS..19..380E Altcode: We describe some aspects of the facility operation that have been considered for the design of the data handling and control of the European Solar Telescope. The main sub-systems of the EST relevant for the control are summarized, together with some information on current solar data models. Title: What happened at ESA's Meteor Research Group in 2010/11? Authors: Koschny, D. V.; McAuliffe, J.; Bettonvil, F. C. M.; Gritsevich, M.; van der Luijt, C.; Ocaña, F.; Smit, H.; Svedhem, H.; Zender, J. J. Bibcode: 2012pimo.conf...57K Altcode: A lot of activities took place in 2010/11 in the Meteor Research Group (MRG) of the European Space Agency's (ESA) Research and Scientific Support Department. Both special observing campaigns as well as continuous observations were performed, mainly with intensified video cameras, but also still with CCD cameras. This paper gives an overview of the activities. Title: Maximizing the Performance of Automated Low Cost All-sky Cameras Authors: Bettonvil, F. Bibcode: 2011msss.conf..363B Altcode: No abstract at ADS Title: The Polarization Optics for the European Solar Telescope Authors: Bettonvil, F. C. M.; Collados, M.; Feller, A.; Gelly, B. F.; Keller, C. U.; Kentischer, T. J.; López Ariste, A.; Pleier, O.; Snik, F.; Socas-Navarro, H. Bibcode: 2011ASPC..437..329B Altcode: EST, the European Solar Telescope, is a 4-m class solar telescope, which will be located at the Canary Islands. It is currently in the conceptual design phase as a European funded project. In order to fulfill the stringent requirements for polarimetric sensitivity and accuracy, the polarimetry has been included in the design work from the very beginning. The overall philosophy has been to use a combination of techniques, which includes a telescope with low (and stable) instrumental polarization, optimal full Stokes polarimeters, differential measurement schemes, fast modulation and demodulation, and accurate calibration, and at the same time not giving up flexibility. The current baseline optical layout consists of a 14-mirror layout, which is polarimetrically compensated and non-varying in time. In the polarization free F2 focus ample space is reserved for calibration and modulators and a polarimetric switch. At instrument level the s-, and p-planes of individual components are aligned, resulting in a system in which eigenvectors can travel undisturbed through the system. Title: Digital All-sky cameras VI: Camera design Authors: Bettonvil, F. Bibcode: 2011pimo.conf...16B Altcode: In this sixth paper about the development of a digital All-sky camera the final design is described. The camera is based on a Canon EOS 350D, Sigma 4.5mm/F2.8 EX DC fisheye lens and a LC-TEC liquid crystal optical chopper. Title: Digital All-sky Cameras IV: Sinodial Shutter Design Authors: Bettonvil, Felix Bibcode: 2010pim7.conf....8B Altcode: 2010pimo.conf....8B In this fourth paper about digital all-sky cameras I describe the design and construction of a new type of shutter for accurate determination of the velocity of meteors. It combines sinodial modulation of the meteor trail with frequency a nalysis for finding the velocity. Two alternatives are discussed. Title: Perseïden vanuit Bosnië Authors: Bettonvil, Felix Bibcode: 2010eRad....6..138B Altcode: Report on visual and photographic meteor observations during the Perseïds 2010 in Bosnia Title: The Irkutsk Barium filter for narrow-band wide-field high-resolution solar images at the Dutch Open Telescope Authors: Hammerschlag, Robert H.; Skomorovsky, Valery I.; Bettonvil, Felix C. M.; Kushtal, Galina I.; Olshevsky, Vyacheslav L.; Rutten, Robert J.; Jägers, Aswin P. L.; Sliepen, Guus; Snik, Frans Bibcode: 2010SPIE.7735E..85H Altcode: 2010SPIE.7735E.265H A wide-field birefringent filter for the barium II line at 455.4nm is developed in Irkutsk. The Barium line is excellent for Doppler-shift measurements because of low thermal line-broadening and steep flanks of the line profile. The filter width is 0.008nm and the filter is tunable over 0.4nm through the whole line and far enough in the neighboring regions. A fast tuning system with servomotor is developed at the Dutch Open Telescope (DOT). Observations are done in speckle mode with 10 images per second and Keller-VonDerLühe reconstruction using synchronous images of a nearby bluecontinuum channel at 450.5nm. Simultaneous observation of several line positions, typically 3 or 5, are made with this combination of fast tuning and speckle. All polarizers are birefringent prisms which largely reduced the light loss compared to polarizing sheets. The advantage of this filter over Fabry-Perot filters is its wide field due to a large permitted entrance angle and no need of polishing extremely precise surfaces. The BaII observations at the DOT occur simultaneously with those of a fast-tunable birefringent H-alpha filter. This gives the unique possibility of simultaneous speckle-reconstructed observations of velocities in photosphere (BaII) and chromosphere (H-alpha). Title: European Solar Telescope: project status Authors: Collados, M.; Bettonvil, F.; Cavaller, L.; Ermolli, I.; Gelly, B.; Grivel-Gelly, C.; Pérez, A.; Socas-Navarro, H.; Soltau, D.; Volkmer, R. Bibcode: 2010SPIE.7733E..0HC Altcode: 2010SPIE.7733E..15C The European Solar Telescope is a project for a 4-meter class telescope to be located in the Canary Islands. EST is promoted by the European Association for Solar Telescopes (EAST). This is a consortium formed by a number of research organizations from fifteen European countries (Austria, Croatia, Czech Republic, France, Germany, Hungary, Italy, the Netherlands, Norway, Poland, Slovak Republic, Spain, Sweden, Switzerland, and United Kingdom). EST will specialize in high spatial and temporal resolution using diverse instruments that can efficiently produce two-dimensional spectropolarimetric information of the thermal, dynamic and magnetic properties of the plasma over many scale heights in the solar atmosphere. In this contribution, the status of the development of the Design Study of EST is presented, emphasizing the most important aspects of the optical design, mechanical structure, AO and MCAO systems for wavefront correction, instruments and polarization analysis. Title: Site-seeing measurements for the European Solar Telescope Authors: Berkefeld, Th.; Bettonvil, F.; Collados, M.; López, R.; Martín, Y.; Peñate, J.; Pérez, A.; Scharmer, G. B.; Sliepen, G.; Soltau, D.; Waldmann, T. A.; van Werkhoven, T. Bibcode: 2010SPIE.7733E..4IB Altcode: 2010SPIE.7733E.141B Seeing measurements are crucial for the optimum design of (multi-conjugate) adaptive optics systems operating at solar telescopes. For the design study of the 4-meter European Solar Telescope, to be located in the Canary Islands, several instruments have been constructed and operated, at the Observatorio del Roque de los Muchachos (La Palma) and at the Observatorio del Teide (Tenerife), to measure the properties of the ground layer and medium-high altitude turbulence. Several units of short (42.34 cm) and two long (323.06 cm) scintillometer bars are, or are to be, installed at both observatories. In addition to them, two wide-field wavefront sensors will be attached to the optical beams of the Swedish tower, on La Palma, and of the German VTT, on Tenerife, simultaneously used with the normal operation of the telescopes. These wavefront sensors are of Shack-Hartmann type with ~1 arcminute field of view. In this contribution, the instruments setup and their performance are described. Title: Mechanical design of a completely open-foldable dome for EST Authors: Hammerschlag, Robert H.; Kommers, Johannes N. M.; van Leverink, Simon J.; Bettonvil, Felix C. M.; Visser, Simon; Jägers, Aswin P. L.; Sliepen, Guus Bibcode: 2010SPIE.7733E..0JH Altcode: In the context of the EST design study for a 4m-class solar telescope and a study for large open-foldable domes of the Dutch Technology Foundation STW, a design is made for the 20 to 30m diameter range. Detailed designs are made for three specific diameter sizes: 23, 28 and 33m. Smaller-size open-foldable domes based on tensioned cloth and in use at the Dutch Open Telescope (7m) and the GREGOR (9m) have proven to be all-weather stable and very effective for good seeing conditions for solar telescopes. The cloth has shown no degradation over the past 14 (DOT) resp. 6 (GREGOR) years of experience and no permanent elongation with the frequent de-tensioning and tensioning during opening and closing. The application of cloth permits a dome design leaving, when opened, the telescope completely free without any structure over the telescope and no massive structures besides or under it. Basis for the new design is the available prestretched stable cloth, which is nowadays produced in much stronger qualities than used for DOT and GREGOR. The larger curvature radius requires larger tension in the cloth, but combination with stronger cloth fits for the upscaling. Calculations show that the steel construction geometries of the GREGOR dome can be upscaled with a few adjustments. Bearings and drives remain within normal sizes. Cost calculations show that open-foldable domes of this size are remarkably lower in price than closed domes. In addition, an interesting option is presented for a semi-transparent windshield of which the position can be adapted to the wind direction. This shield gives an effective wind protection of the region around the primary mirror without disturbing the wind flows above the shield and without stagnant air or big eddies behind it. It is storm safe and the costs are only a fraction of the open-foldable dome costs. Title: The pier and building of the European Solar Telescope (EST) Authors: Bettonvil, F. C. M.; Codina, R.; Gómez Merchán, A.; Hammerschlag, R. H.; Hartman, J. J. M.; Hernández Suárez, E.; Jägers, A. P. L.; Murga Llano, G.; Pelser, J. W.; Sliepen, G. Bibcode: 2010SPIE.7733E..34B Altcode: 2010SPIE.7733E..97B EST (European Solar Telescope) is a 4-m class solar telescope, which is currently in the conceptual design phase. EST will be located in the Canary Islands and will aim at high spectral, spatial and temporal resolution observations in the photosphere and chromosphere, using a suite of instruments that can produce efficiently two-dimensional spectropolarimetric information of the thermal, dynamic and magnetic properties of the plasma over many scale heights. The pier is defined as the construction that supports the telescope and the enclosure. It needs a certain height to minimize daytime ground turbulence. At the bottom of the pier a large instrument lab is located, 16 m in diameter and 10 m high. To the pier is attached a service building that accommodates all auxiliary services, possibly together with a separate building. Solid concrete- and open framework piers are compared, in terms of stability, thermal properties and flow characteristics and building structures in terms of construction issues. FE and CFD analysis are used to give qualitative insight in the differences between the alternatives. The preferred alternative is a cone shaped pier surrounded by an open framework. Title: Foldable dome climate measurements and thermal properties Authors: Sliepen, Guus; Jägers, Aswin P. L.; Hammerschlag, Robert H.; Bettonvil, Felix C. M. Bibcode: 2010SPIE.7733E..32S Altcode: 2010SPIE.7733E..95S As part of a larger project for measuring various aspects of foldable domes in the context of EST and with support of the Dutch Technology Foundation STW, we have collected over a year of continuous temperature and humidity measurements, both inside and outside the domes of the Dutch Open Telescope (DOT) on La Palma5 and the GREGOR telescope on Tenerife.6 In addition, we have measured the wind field around each dome. Although the structure of both domes is similar, the DOT dome has a single layer of cloth, and is situated on top of an open tower. In contrast, the GREGOR dome has a double layer of cloth, and is situated on top of a tower-shaped building. These differences result in large differences in temperature and humidity insulation when the dome is closed. We will present the changes in temperature and humidity one can expect for each dome within one day, and the statistics for the variations throughout a year. In addition, we will show that the main advantage of a foldable dome is the near instantaneous equilibration of the air inside the volume originally enclosed by the dome and that of the environment outside the dome. This property allows one to operate a telescope without needing expensive air conditioning and dome skin temperature control in order to limit dome and shell seeing effects. The measurements give also information about the weather fluctuations at the sites of the domes. It was observed that on small time scales the temperature fluctuations are significantly greater during the day than during the night. Title: The heat stop for the 4-m European Solar Telescope EST Authors: Berrilli, F.; Egidi, A.; Del Moro, D.; Manni, F.; Cocciolo, M.; Scotto, A.; Volkmer, R.; Bettonvil, F. C. M.; Collados Vera, M.; Cavaller Marquez, L.; Sanchez Capuchino, J. Bibcode: 2010SPIE.7733E..2ZB Altcode: 2010SPIE.7733E..92B A study is presented for the realization of the heat stop for the 4-m European Solar Telescope EST, whose feasibility study will be completed in 2011. EST is an on-axis Gregorian telescope, equipped with a four-meter diameter primary mirror and primary focal length of about six meters. The heat stop, positioned at the primary focus, must be able to remove a heat load of 13 kW, while maintaining its surfaces very close to room temperature, to avoid the onset of seeing. In order to remove the heat, three configurations have been taken into consideration: 1) a flat 45° inclined heat rejecter, 2) a 45° conical heat rejecter and 3) a heat trap (made of a conical heat rejecter and a cylindrical heat absorber). All devices include an air removal system to avoid the formation of thermal plumes. Title: Seeing measurements with autonomous, short-baseline shadow band rangers Authors: Sliepen, Guus; Jägers, Aswin P. L.; Bettonvil, Felix C. M.; Hammerschlag, Robert H. Bibcode: 2010SPIE.7733E..4LS Altcode: 2010SPIE.7733E.144S There is growing interest in measuring seeing at existing and prospective telescope sites. Several methods exist to quantify seeing, one among them is by measuring the scintillation of solar or lunar light using a photodiode. A shadow band ranger (SHABAR) analyses the covariance of the signals from an array of such photodiodes, which allows for the spatial resolution of the index of refraction above the SHABAR device. This allows one to estimate the index of refraction structure parameter as a function of height, C2n(h). Although a SHABAR has a limited range compared to a differential image motion monitor (DIMM) or the latest wavefront sensors, the advantage is that it does not need telescope optics to work. A SHABAR device can be made very compact and can operate independent of other instruments. We describe the design of such a SHABAR device with six photodiodes that can operate virtually indefinitely without requiring human intervention. An inversion algorithm is used to convert the raw scintillation signals of the photodiodes to the desired C2n(h) profile and a value for the Fried parameter r0 at height zero. We show that it is possible to perform inversions of 10 s periods in real time on relatively low-end hardware, such as an Intel Atom based computer, which allows the results to be presented live to astronomers, who can use this information to help make decisions about their observation schedule. Title: The enclosure for the European Solar Telescope (EST) Authors: Bettonvil, F. C. M.; Codina, R.; Hammerschlag, R. H.; Jägers, A. P. L.; Kommers, J. N. M.; van Leverink, S. J.; Sliepen, G.; Visser, S. Bibcode: 2010SPIE.7733E..33B Altcode: 2010SPIE.7733E..96B The European Solar Telescope (EST) is a 4-m class solar telescope, which is currently in the conceptual design phase. EST will be located in the Canary Islands and aims at observations with high spectral, spatial and temporal resolution of the solar photosphere and chromosphere. The main purpose of the enclosure is to protect the telescope and instruments from severe weather conditions. An enclosure is also often needed for reducing wind buffeting on the telescope and primary mirror cell, but on the other hand enclosures are generally considered to degrade local seeing. In this contribution we will present the conceptual design of the enclosure for EST. Two different concepts have been studied in more detail: the first being a dome concept with vent gates to enhance local flushing, the other being a retractable enclosure, with an optional windshield. Technically both alternatives seem feasible, but we conclude that the retractable enclosure is the less risky solution, since it allows easier local seeing control and allows the use of a reflecting heat stop in the primary focus. A windshield is effective in reducing wind load on the primary mirror; although preliminary analysis indicate that there are feasible solutions to keep the deformation caused by wind buffeting within the requirements. Title: EST Telescope: primary mirror, support, and cooling system Authors: Volkmer, R.; Manni, F.; Giannuzzi, M.; Scotto, A.; Cavaller, L.; Scheiffelen, T.; Bettonvil, F.; Berrilli, F. Bibcode: 2010SPIE.7739E..1OV Altcode: 2010SPIE.7739E..52V The solar telescope EST is currently in the conceptual design phase. It is planned to be build on the Canary Islands until end of the decade. It is specialized on polarimetric observations and will provide high spatial and spectral observations of the different solar atmospheric layers. The diameter of the primary mirror blank is 4.2m. Different types of mirror shapes were investigated with respect to thermal and mechanical characteristics. To remove the absorbed heat an air cooling system from the back side will be applied. Additional an air flushing system will remove remaining warm air from the front side. A major problem of a large open telescope will be the wind load. Results of the investigations will be shown. To achieve optimal optical performance an active support system is planned. The primary mirror cell needs to be stiff enough to support the primary mirror without deformation at strong wind in case of the open telescope option, but sufficient room for the active support system and cooling system below the backside of the mirror is also required. Preliminary designs and analysis results will be presented. Title: The polarization optics for the European Solar Telescope (EST) Authors: Bettonvil, F. C. M.; Collados, M.; Feller, A.; Gelly, B. F.; Keller, C. U.; Kentischer, T. J.; López Ariste, A.; Pleier, O.; Snik, F.; Socas-Navarro, H. Bibcode: 2010SPIE.7735E..6IB Altcode: 2010SPIE.7735E.214B EST (European Solar Telescope) is a 4-m class solar telescope, which is currently in the conceptual design phase. EST will be located at the Canary Islands and aims at observations with the best possible spectral, spatial and temporal resolution and best polarimetric performance, of the solar photosphere and chromosphere, using a suite of instruments that can efficiently produce two-dimensional spectropolarimetric information of the thermal, dynamic and magnetic properties of the plasma over many scale heights, and ranging from λ=350 until 2300 nm. In order to be able to fulfill the stringent requirements for polarimetric sensitivity and accuracy, from the very beginning the polarimetry has been included in the design work. The overall philosophy has been to use a combination of techniques, which includes a telescope with low (and stable) instrumental polarization, optimal full Stokes polarimeters, differential measurement schemes, fast modulation and demodulation, and accurate calibration. The current baseline optical layout consists of a 14-mirror layout, which is polarimetrically compensated and nonvarying in time. In the polarization free F2 focus ample space is reserved for calibration and modulators and a polarimetric switch. At instrument level the s-, and p-planes of individual components are aligned, resulting in a system in which eigenvectors can travel undisturbed through the system. Title: Data handling and control for the European Solar Telescope Authors: Ermolli, Ilaria; Bettonvil, Felix; Cauzzi, Gianna; Cavaller, Lluis; Collados, Manuel; Di Marcantonio, Paolo; Paletou, Frederic; Romano, Paolo; Aboudarham, Jean; Cirami, Roberto; Cosentino, Rosario; Giorgi, Fabrizio; Lafon, Martine; Laforgue, Didier; Reardon, Kevin; Sliepen, Guus Bibcode: 2010SPIE.7740E..0GE Altcode: 2010SPIE.7740E..13E We introduce the concepts for the control and data handling systems of the European Solar Telescope (EST), the main functional and technical requirements for the definition of these systems, and the outcomes from the trade-off analysis to date. Concerning the telescope control, EST will have performance requirements similar to those of current medium-sized night-time telescopes. On the other hand, the science goals of EST require the simultaneous operation of three instruments and of a large number of detectors. This leads to a projected data flux that will be technologically challenging and exceeds that of most other astronomical projects. We give an overview of the reference design of the control and data handling systems for the EST to date, focusing on the more critical and innovative aspects resulting from the overall design of the telescope. Title: Auxiliary full-disc telescope for the European Solar Telescope Authors: Sobotka, Michal; Klvaña, Miroslav; Melich, Zbynék; Rail, Zdenék; Bettonvil, Felix; Gelly, Bernard Bibcode: 2010SPIE.7735E..1ZS Altcode: 2010SPIE.7735E..67S The Auxiliary Full-Disc Telescope (AFDT) will be used for the orientation of the observer on the solar disc and in its surroundings, for an easy guidance of the European Solar Telescope (EST) to a selected target, and for precise coordinate measurements. AFDT can be used as an autonomous robotic telescope for synoptic observations and records of solar activity also when no observations are carried out at the EST main telescope. The principal functions of AFDT and the related requirements are summarised. The specific axial mechanical structure accommodating the refractor optical system is outlined. The optical system and its components are described. Two alternatives of the positional control system - the active guiding system and the passive guiding system - are described and their functionality is analysed. Title: European Solar Telescope: Progress status Authors: Collados, M.; Bettonvil, F.; Cavaller, L.; Ermolli, I.; Gelly, B.; Pérez, A.; Socas-Navarro, H.; Soltau, D.; Volkmer, R.; EST Team Bibcode: 2010AN....331..615C Altcode: In this paper, the present status of the development of the design of the European Solar Telescope is described. The telescope is devised to have the best possible angular resolution and polarimetric performance, maximizing the throughput of the whole system. To that aim, adaptive optics and multi-conjugate adaptive optics are integrated in the optical path. The system will have the possibility to correct for the diurnal variation of the distance to the turbulence layers, by using several deformable mirrors, conjugated at different heights. The present optical design of the telescope distributes the optical elements along the optical path in such a way that the instrumental polarization induced by the telescope is minimized and independent of the solar elevation and azimuth. This property represents a large advantage for polarimetric measurements. The ensemble of instruments that are planned is also presented. Title: Digital All-sky cameras V: Liquid Crystal Optical Shutters Authors: Bettonvil, Felix Bibcode: 2010pim9.conf...14B Altcode: 2010pimo.conf...14B In this fifth paper about digital All-sky cameras I present a Liquid Crystal Optical Shutter that can be used for determination of the velocity of meteors. The aim is to modulate the shutter signal with a sinusoidal function and use frequency analysis to compute the velocity. Title: Open Principle for Large High-Resolution Solar Telescopes Authors: Hammerschlag, Robert H.; Bettonvil, Felix C. M.; Jägers, Aswin P. L.; Sliepen, Guus Bibcode: 2009EM&P..104...83H Altcode: 2008EM&P..tmp...38H Vacuum solar telescopes solve the problem of image deterioration inside the telescope due to refractive index fluctuations of the air heated by the solar light. However, such telescopes have a practical diameter limit somewhat over 1 m. The Dutch Open Telescope (DOT) was the pioneering demonstrator of the open-telescope technology without need of vacuum, now pursued in the German GREGOR. Important ingredients for this technology are primary beam completely open to natural wind flow, stiff but still open design by principal stiff overall geometries in combination with carefully designed joints and completely open-foldable dome constructions based on tensioned strong cloth. Further developments to large sizes are made within the framework of the design study for a European Solar Telescope (EST). Title: The meteor year of the Meteor Research Group of the European Space Agency's Research and Scientific Support Department Authors: Koschny, D. V.; McAuliffe, J.; Barentsen, G.; Bettonvil, F. C. M.; Hatton, J. P.; Lowiessen, F.; Zender, J. J. Bibcode: 2008JIMO...36..131K Altcode: A lot of activities took place in 2007 at the Meteor Research Group (MRG) of the European Space Agency's (ESA) Research and Scientific Support Department (RSSD). Both special observing campaigns as well as continuous observations were performed, mainly with intensified video cameras, but also with still CCD cameras. Over 1400 meteors were observed; about 150 meteors were observed from more than one station allowing orbit computations. In addition to collecting observational data, ESA/RSSD further pursued the idea of setting up standards for a `Virtual Meteor Observatory'. The activities are summarized here to allow referencing for more detailed, scientific papers. Title: Large fully retractable telescope enclosures still closable in strong wind Authors: Bettonvil, Felix C. M.; Hammerschlag, Robert H.; Jägers, Aswin P. L.; Sliepen, Guus Bibcode: 2008SPIE.7018E..1NB Altcode: 2008SPIE.7018E..52B Two prototypes of fully retractable enclosures with diameters of 7 and 9 m have been built for the high-resolution solar telescopes DOT (Dutch Open Telescope) and GREGOR, both located at the Canary Islands. These enclosures protect the instruments for bad weather and are fully open when the telescopes are in operation. The telescopes and enclosures also operate in hard wind. The prototypes are based on tensioned membrane between movable but stiff bows, which fold together to a ring when opened. The height of the ring is small. The prototypes already survived several storms, with often snow and ice, without any damage, including hurricane Delta with wind speeds up to 68 m/s. The enclosures can still be closed and opened with wind speeds of 20 m/s without any problems or restrictions. The DOT successfully demonstrated the open, wind-flushing concept for astronomical telescopes. It is now widely recognized that also large future telescopes benefit from wind-flushing and retractable enclosures. These telescopes require enclosures with diameters of 30 m until roughly 100 m, the largest sizes for the ELTs (Extreme Large Telescopes), which will be built in the near future. We discuss developments and required technology for the realization of these large sizes. Title: Contactless sub-millimeter displacement measurements Authors: Sliepen, Guus; Jägers, Aswin P. L.; Bettonvil, Felix C. M.; Hammerschlag, Robert H. Bibcode: 2008SPIE.7018E..1CS Altcode: 2008SPIE.7018E..41S Weather effects on foldable domes, as used at the DOT and GREGOR, are investigated, in particular the correlation between the wind field and the stresses caused to both metal framework and tent clothing. Camera systems measure contactless the displacement of several dome points. The stresses follow from the measured deformation pattern. The cameras placed near the dome floor do not disturb telescope operations. In the set-ups of DOT and GREGOR, these cameras are up to 8 meters away from the measured points and must be able to detect displacements of less than 0.1 mm. The cameras have a FireWire (IEEE1394) interface to eliminate the need for frame grabbers. Each camera captures 15 images of 640 × 480 pixels per second. All data is processed on-site in real-time. In order to get the best estimate for the displacement within the constraints of available processing power, all image processing is done in Fourier-space, with all convolution operations being pre-computed once. A sub-pixel estimate of the peak of the correlation function is made. This enables to process the images of four cameras using only one commodity PC with a dual-core processor, and achieve an effective sensitivity of up to 0.01 mm. The deformation measurements are well correlated to the simultaneous wind measurements. The results are of high interest to upscaling the dome design (ELTs and solar telescopes). Title: Cornelis Zwaan, open principle, and the future of high-resolution solar telescopes Authors: Hammerschlag, Robert H.; Bettonvil, Felix C. M.; Jägers, Aswin P. L.; Sliepen, Guus Bibcode: 2008SPIE.7012E..0MH Altcode: 2008SPIE.7012E..20H It was in the years around 1970 that during site-test campaigns for JOSO masts were erected up till 30 m height with sensors at several heights for the measurement of temperature fluctuations. Cornelis (Kees) Zwaan discovered that the fluctuations decrease drastically at heights from about 15 m and upward when there is some wind. The conclusion from this experience was the open telescope principle: the telescope should be completely free in the air 15 m or more above the ground. The Dutch Open Telescope (DOT) was the pioneering demonstrator of the open-telescope technology. Now that larger high-resolution telescopes come in view, it is time to analyze again the principle: (i) the essentials for proper working of the open principle; (ii) the differences with nighttime observations particularly concerning the seeing; (iii) the design consequences for the new generation of high-resolution solar telescopes. Title: Fast foldable tent domes Authors: Jägers, Aswin P. L.; Sliepen, Guus; Bettonvil, Felix C. M.; Hammerschlag, Robert H. Bibcode: 2008SPIE.7018E..1RJ Altcode: 2008SPIE.7018E..56J In the near future ELTs (Extreme Large Telescopes) will be built. Preferably these telescopes should operate without obstructions in the near surrounding to reach optimal seeing conditions and avoid large turbulences with wind-gust accelerations around large obstacles. This applies also to future large solar telescopes. At present two foldable dome prototypes have been built on the Canary Islands: the Dutch Open Telescope (DOT, La Palma) and the GREGOR Telescope (Tenerife), having a diameter of 7 and 9 meter, respectively. The domes are usually fully retracted during observations. The research consists of measurements on the two domes. New camera systems are developed and placed inside the domes for precise dome deformation measurements within 0.1 mm over the whole dome size. Simultaneously, a variety of wind-speed and -direction sensors measure the wind field around the dome. In addition, fast sensitive air-pressure sensors placed on the supporting bows measure the wind pressure. The aim is to predict accurately the expected forces and deformations on up-scaled, fully retractable domes to make their construction more economically. The dimensions of 7 and 9 meter are large enough for realistic on-site tests in gusty wind and will give much more information than wind tunnel experiments. Title: Determination of the Velocity of Meteors Based on Sinodial Modulation and Frequency Analysis Authors: Bettonvil, Felix Bibcode: 2008EM&P..102..205B Altcode: 2007EM&P..tmp...41B In meteor photography the velocity of meteors is generally obtained from a chopper which blocks periodically the incident light beam in front of the camera lens. In this paper I examine modulation of the meteor trail instead with a sinodial function and use frequency analysis to compute accurately the mean atmospheric velocity. Title: Drie Palmanese winterakties op een rij: Geminiden, Ursiden en Quadrantiden Authors: Bettonvil, Felix Bibcode: 2008eRad....4...40B Altcode: Report on visual observations of the Geminids 2007, Ursids 2007 and Quadrantids 2008 Title: IMC 2006 Proceedings now available Authors: Bettonvil, Felix Bibcode: 2008JIMO...36....4B Altcode: No abstract at ADS Title: Orioniden 2007 Authors: Bettonvil, Felix Bibcode: 2008eRad....4...16B Altcode: Report on visual observations of the Orionids 2007 Title: Organizer's notes Authors: Hartman, Joost; Bettonvil, F. Bibcode: 2007pimo.conf....1H Altcode: No abstract at ADS Title: Digital All-sky cameras II: A new method for velocity determination Authors: Bettonvil, Felix Bibcode: 2007pimo.conf..134B Altcode: In this second paper about digital All-sky cameras I present a new type of shutter for determination of the velocity of meteors which together with frequency analysis can lead to a higher precision. Title: Digital All-sky cameras III: Effect if Peltier cooling on fixed pattern noise Authors: Bettonvil, Felix Bibcode: 2007pimo.conf..138B Altcode: In this third paper in a series about digital All-sky cameras I describe the problem of the camera background level which limits long exposures and the effect of cooling to reduce it. Title: Proceedings of the International Meteor Conference, Roden 2006 Authors: Bettonvil, Felix; Kac, Javor Bibcode: 2007pimo.conf.....B Altcode: No abstract at ADS Title: Een snufje Perseïden vanuit La Palma Authors: Bettonvil, Felix Bibcode: 2007eRad....3..168B Altcode: Report on visual and photographic observations of the Perseïds 2007 at La Palma, Spain Title: ESA's double station meteor program: development, deployment, initial results. Authors: Mc Auliffe, J.; Koschny, D.; Lowiessen, F.; Bettonvil, F. C. M. Bibcode: 2007epsc.conf..730M Altcode: Over the past 18 months ESA's meteor research group has developed, installed and began operating 2 permanent double station meteor observatories in the Netherlands, and on the Canary Islands. Both systems use image intensified video cameras and baselines of approximately 93 and 140 km, respectively, to observe the same volume of atmosphere (near 100 km in altitude) for the luminous effects of meteor ablation. Events captured by both cameras in either system are analysed dynamically in order to determine atmospheric trajectories and subsequently pre-atmospheric orbits, as well as photometrically, to provide estimates of the initial masses of the ablating particles. Here, the particulars of the 2 double station systems will be presented, an overview of the analysis process will be given and the initial results from this analysis discussed. Title: Aperture Increase Options for the Dutch Open Telescope Authors: Hammerschlag, R. H.; Bettonvil, F. C. M.; Jägers, A. P. L.; Rutten, R. J. Bibcode: 2007ASPC..368..573H Altcode: 2007astro.ph..3638H This paper is an invitation to the international community to participate in the usage and a substantial upgrade of the Dutch Open Telescope on La Palma (DOT, http://dot.astro.uu.nl).

We first give a brief overview of the approach, design, and current science capabilities of the DOT. It became a successful 0.2-arcsec-resolution solar movie producer through its combination of (i) an excellent site, (ii) effective wind flushing through the fully open design and construction of both the 45-cm telescope and the 15-m support tower, (iii) special designs which produce extraordinary pointing stability of the tower, equatorial mount, and telescope, (iv) simple and excellent optics with minimum wavefront distortion, and (v) large-volume speckle reconstruction including narrow-band processing. The DOT's multi-camera multi-wavelength speckle imaging system samples the solar photosphere and chromosphere simultaneously in various optical continua, the G band, Ca II H (tunable throughout the blue wing), and Hα (tunable throughout the line). The resulting DOT data sets are all public. The DOT database (http://dotdb.phys.uu.nl/DOT) now contains many tomographic image sequences with 0.2-0.3 arcsec resolution and up to multi-hour duration. You are welcome to pull them over for analysis.

The main part of this contribution outlines DOT upgrade designs implementing larger aperture. The motivation for aperture increase is the recognition that optical solar physics needs the substantially larger telescope apertures that became useful with the advent of adaptive optics and viable through the DOT's open principle, both for photospheric polarimetry at high resolution and high sensitivity and for chromospheric fine-structure diagnosis at high cadence and full spectral sampling.

Our upgrade designs for the DOT are presented in an incremental sequence of five options of which the simplest (Option I) achieves 1.4 m aperture using the present tower, mount, fold-away canopy, and multi-wavelength speckle imaging and processing systems. The most advanced (Option V) offers unblocked 2.5 m aperture in an off-axis design with a large canopy, a wide 30-m high support tower, and image transfer to a groundbased optics lab for advanced instrumentation. All five designs employ adaptive optics. The important advantages of fully open, wind-transparent and wind-flushed structure, polarimetric constancy, and absence of primary-image rotation remain. All designs are relatively cheap through re-using as much of the existing DOT hardware as possible.

Realization of an upgrade requires external partnership(s). This report about DOT upgrade options therefore serves also as initial documentation for potential partners. Title: Leoniden 2006 vanaf La Palma Authors: Bettonvil, Felix Bibcode: 2007eRad....3...10B Altcode: Report on visual observations of the Leonids 2006 outburst as seen from La Palma Title: Towers for Antarctic Telescopes Authors: Hammerschlag, R. H.; Bettonvil, F. C. M.; Jägers, A. P. L.; Nielsen, G. Bibcode: 2007EAS....25..265H Altcode: To take advantage of the exceptional seeing above the boundary layer on Antarctic sites, a high-resolution telescope must be mounted on a support tower. An open transparent tower of framework minimizes the upward temperature-disturbed airflow. A typical minimum height is 30m. The tower platform has to be extremely stable against wind-induced rotational motions, which have to be less than fractions of an arc second, unusually small from a mechanical engineering viewpoint. In a traditional structure, structural deflections result in angular deflections of the telescope platform, which introduce tip and tilt motions in the telescope. However, a structure that is designed to deflect with parallel motion relative to the horizontal plane will undergo solely translation deflections in the telescope platform and thus will not degrade the image. The use of a parallel motion structure has been effectively demonstrated in the design of the 15-m tower for the Dutch Open Telescope (DOT) on La Palma. Special framework geometries are developed, which make it possible to construct high towers in stories having platforms with extreme stability against wind-induced tilt. These geometric solutions lead to constructions, being no more massive than a normal steel framework carrying the same load. Consequently, these lightweight towers are well suited to difficult sites as on Antarctica. A geometry with 4 stories has been worked out. Title: The Ba II 4554 / Hβ Imaging Polarimeter for the Dutch Open Telescope Authors: Snik, F.; Bettonvil, F. C. M.; Jägers, A. P. L.; Hammerschlag, R. H.; Rutten, R. J.; Keller, C. U. Bibcode: 2006ASPC..358..205S Altcode: In order to expand the high-resolution, multi-wavelength imaging capabilities of the Dutch Open Telescope (DOT), an additional polarimetric channel based on a 80 mÅ tunable Lyot filter for Ba II 4554 and Hβ has been designed and constructed. The large atomic mass and the resulting steep line wings, make Ba II 4554 particularly suitable for the creation of photospheric Dopplergrams and Stokes-V magnetograms. The line also yields a significant degree of linear (scattering) polarization for observations near the limb of the Sun, which is modified by both horizontal and vertical weak-field topologies through the Hanle effect and hyperfine-structure level crossing. The polarimeter is based on liquid crystal variable retarders (LCVRs) as polarization modulators in combination with the Lyot filter's entrance polarizer. The tunability of the LCVRs is exploited to enable specific wavelength calibration, selection of the reference frame of linear polarization, and optimization of instrumental polarization cross-talk, which for the DOT is constant in time. With the future Ba II 4554 photospheric magnetograms, we expect to be able to discern magnetic structures of about 150 km with field strengths down to 100 G, and that Hanle-type observations can be performed at a resolution of about 1 arcsec. The range of applicability of Hβ imaging polarimetry has to be explored after installation. Title: Orbit calculation of the August 15, 2002 fireball over the Netherlands Authors: Bettonvil, Felix Bibcode: 2006pimo.conf..171B Altcode: On August 15, 2002 at 230350 UT a very bright meteor appeared above the western part of the Netherlands. The fireball, with an estimated magnitude of -8, and visible for about 4 seconds, was simultaneously photographed by three Dutch all-sky cameras operated by members of Dutch Meteor Society and the KNVWS Meteor Section, set up at Oostkapelle, Benningbroek and Hoogmade. Measurements of the three all-sky images and calculation of the trajectory indicated a low vanishing height of the fireball, slightly less than 40 kilometers, and a clear deceleration. The calculated heliocentric orbital elements show similarities with members of the iota-Aquarid shower, and correspond extremely well with the anti-helion ecliptical sporadic background. Title: A digital all-sky camera Authors: Bettonvil, Felix Bibcode: 2006pimo.conf...90B Altcode: We present an automated digital all-sky camera based on a Nikon Coolpix 4500 with FC-E8 fisheye lens. Title: Tunable H-alpha Lyot filter with advanced servo system and image processing: instrument design and new scientific results with the Dutch Open Telescope Authors: Bettonvil, Felix C. M.; Hammerschlag, Robert H.; Sütterlin, Peter; Rutten, Robert J.; Jägers, Aswin P. L.; Sliepen, Guus Bibcode: 2006SPIE.6269E..0EB Altcode: 2006SPIE.6269E..12B The Dutch Open Telescope (DOT; http://dot.astro.uu.nl) on La Palma is a revolutionary open solar telescope, on an excellent site, on top of a transparent tower of steel framework, and uses natural air flow to minimize local seeing. The DOT is a high-resolution multi-wavelength imager capable of long-duration time series aiming at magnetic fine structure, topology and dynamics in the photosphere and low- and high chromosphere. In this paper we describe the latest addition to the multi-wavelength imaging system: a Lyot H-alpha camera channel operating at a wavelength of 656.3 nm, being of major interest for high-chromospheric phenomena. The channel is operated strictly synchronous with the other channels and all data are speckle reconstructed. The channel permits profile sampling and delivers Dopplergrams in a 15 second time cadence, up to several hours long and adding up to a total data amount of 1.6 Terabyte/day. A dedicated computer (DSP, DOT Speckle Processor) has been built for processing the data overnight. Title: Towers for telescopes with extreme stability: Active or passive? Authors: Hammerschlag, Robert H.; Bettonvil, Felix C. M.; Jägers, Aswin P. L. Bibcode: 2006SPIE.6273E..1OH Altcode: 2006SPIE.6273E..50H High-resolution telescopes require a mechanical stability of fractions of an arc second. Placing such a telescope on top of a tower will improve the local seeing. An open transparent tower of framework minimizes the upward, temperature disturbed air flow. The tower platform has to be extremely stable against rotational motions, which have to be less than fractions of an arc second, unusual in mechanical engineering. Active systems can improve the stability. However, they need sensors for position measurements, active actuators and a control loop. The performance is limited by the available signal-to-noise ratio. Consequently, improvement of the passive stability of large tower structures will significantly contribute to the final stability. Special geometries in steel framework can reach extreme passive stability of a tower platform, particularly against rotational motions. There are several groups of basic geometries, which lead to solutions and we will give a systematic description. The proposed towers can be welded or screwed together from smaller parts. This makes a construction in adverse environments like the Antarctic region within good reach. Title: Large bearings with incorporated gears, high stiffness, and precision for the Swedish Solar Telescope (SST) on La Palma Authors: Hammerschlag, Robert H.; Bettonvil, Felix C. M.; Jägers, Aswin P. L.; Scharmer, Göran B. Bibcode: 2006SPIE.6273E..15H Altcode: 2006SPIE.6273E..34H The 1-meter Swedish Solar Telescope (SST) obtains images of the solar surface with an unprecedented resolution of 0.1 arcsec. It consists of a relatively slender tower with on top only the vacuum turret for reflecting downward the solar beam and no protective dome. This is a favourable situation to get good local seeing. Just in the case of some wind, seeing is best for daytime observations, therefore the precision bearings and drives of the elevation- and azimuth axis of the turret have to be stiff against wind. This requires line contact between the meshing teeth of the large gear wheel and the pinion. High preload forces to achieve line contact are not allowed because of appearing stick-slip effects. To reduce the risk on stick-slip a special design of the teeth for high stiffness combined with low friction and smooth transition from one tooth to the next was made. Furthermore, extreme precision in the fabrication was pursued such that relatively small contact forces give already line contact. This required a special order of the successive fabrication steps of the combination of bearing and gear teeth. An additional problem was the relatively thin section of the bearings required for a compact turret construction, needed for best local seeing and minimum wind load. Solutions for all these problems will be discussed. For the large gears the exceptional good DIN quality class 4 for the pitch precision and straightness plus direction of the teeth faces was achieved. Title: Fisheye lenses Authors: Bettonvil, F. Bibcode: 2005JIMO...33....9B Altcode: In meteor astronomy the fisheye lens is well known, in particular in the field of fireball imaging. In this paper all relevant characteristics of the fisheye lens are described and compared with their alternatives. Title: GISOT: a giant solar telescope Authors: Hammerschlag, Robert H.; von der Lühe, Oskar F.; Bettonvil, Felix C.; Jägers, Aswin P.; Snik, Frans Bibcode: 2004SPIE.5489..491H Altcode: A concept is presented for an extremely large high-resolution solar telescope with an aperture of 11 m and diffraction limited for visual wavelengths. The structure of GISOT will be transparent to wind and placed on a transparent stiff tower. For efficient wind flushing, all optics, including the primary mirror, will be located above the elevation axis. The aperture will be of the order of 11 m, not rotatively symmetrical, but of an elongated shape with dimensions 11 x 4 m. It consists of a central on-axis 4 m mirror with on both sides 3 pieces of 2 m mirrors. The optical layout will be kept simple to guarantee quality and minimize stray light. A Coudé room for instruments is planned below the telescope. The telescope will not be housed in a dome-like construction, which interferes with the open principle. Instead the telescope will be protected by a foldable tent construction with a diameter of the order of 30 m, which doesn"t form any obstruction during observations, but can withstand the severe weather circumstances on mountain sites. Because of the nature of the solar scene, extremely high resolution in only one dimension is sufficient to solve many exciting problems in solar physics and in this respect the concept of GISOT is very promising. Title: DOT++: the Dutch Open Telescope with 1.4-m aperture Authors: Bettonvil, Felix C.; Hammerschlag, Robert H.; Sütterlin, Peter; Rutten, Robert J.; Jägers, Aswin P.; Snik, Frans Bibcode: 2004SPIE.5489..362B Altcode: The Dutch Open Telescope (DOT; http://dot.astro.uu.nl) on La Palma is a revolutionary open solar telescope, on an excellent site, on top of a transparent steel tower, and uses natural air flow to minimize local seeing. The aim is long-duration high-resolution imaging with a multi-wavelength camera system. In order to achieve this, the DOT is equipped with a diffraction limited imaging system and uses the speckle reconstruction technique for removing the remaining atmospheric turbulence. The DOT optical system is simple and consists currently of a 0.45m/F4.44 parabolic mirror and a 10x enlargement lens system. We present our plans to increase the aperture of the DOT from 0.45m to 1.4m. The mirror support and telescope top shall be redesigned, but telescope, tower, multi-wavelength camera system and speckle system remain intact. The new optical design permits user selectable choice between angular resolution and field size, as well as transversal pupil shift introducing the possibility to use obstruction free apertures up to 65cm. The design will include a low order AO system, which improves the speckle S/N substantially during moderate seeing conditions. Title: The Dutch Open Telescope on La Palma Authors: Rutten, R. J.; Bettonvil, F. C. M.; Hammerschlag, R. H.; Jägers, A. P. L.; Leenaarts, J.; Snik, F.; Sütterlin, P.; Tziotziou, K.; de Wijn, A. G. Bibcode: 2004IAUS..223..597R Altcode: 2005IAUS..223..597R The Dutch Open Telescope (DOT) on La Palma is an innovative solar telescope combining open telescope structure and an open support tower with a multi-wavelength imaging assembly and with synchronous speckle cameras to generate high-resolution movies which sample different layers of the solar atmosphere simultaneously and co-spatially at high resolution over long durations. The DOT test and development phase is nearly concluded. The installation of an advanced speckle processor enables full science utilization including "Open-DOT" time allocation to the international community. Co-pointing with spectropolarimeters at other Canary Island telescopes and with TRACE furnishes valuable Solar-B precursor capabilities. Title: FIFIE - Fireball Filming Equipment: All sky imaging with video Authors: Bettonvil, F. Bibcode: 2004pimo.conf....8B Altcode: This contribution revolves around the construction of a video camera equipped with a fisheye lens for the observation of fireballs. The described camera Fifie (Fireball Filming Equipment) will be installed in Utrecht, centrally located in the Netherlands, being able to witness any fireball sighting above the lowlands. It is a valuable support for visual fireball reports as it can provide accurate timing. Such a camera must be seen as an addition to photographic all-sky cameras because its lower spatial resolution cannot replace them. On the other hand, the effort to make such a camera operational is reduced to a minimum. It has the potential to be used by a much larger group of meteor observers, improving the quality of a fireball network too. Title: DOT tomography of the solar atmosphere. I. Telescope summary and program definition Authors: Rutten, R. J.; Hammerschlag, R. H.; Bettonvil, F. C. M.; Sütterlin, P.; de Wijn, A. G. Bibcode: 2004A&A...413.1183R Altcode: The Dutch Open Telescope (DOT) on La Palma is an innovative optical solar telescope capable of reaching 0.2 arcsec angular resolution over extended durations. The DOT presently progresses from technology testbed to a stable science configuration providing multi-wavelength imaging and multi-camera speckle data acquisition for tomographic mapping of the solar atmosphere. Large-volume speckle processing will soon enable frequent usage and community-wide time allocation, in particular for tandem operation with other solar telescopes pursuing spectropolarimetry and EUV imaging. We summarize the DOT hardware and software in the context of this increasing availability and outline the corresponding ``open-DOT'' program. Title: What can an urban observer do? Video work from downtown Authors: Bettonvil, F. Bibcode: 2003JIMO...31...38B Altcode: This paper demonstrates that, even from light polluted areas, useful meteor work can be done. In the center of a medium sized city an intensified video system was set up and the goal, instead of activity monitoring, was to do some orbit analysis. In April 2001, around the Lyrid maximum, multi-station observations were conducted from two stations, and together 50~meteor trails containing five double-station meteors were collected. As an example, three Lyrids were analyzed and their orbits calculated. The results illustrate that it is quite possible to do this kind of work under less favorable circumstances, but also showed some general problems with video multi-station work: neither radiant nor velocity could be determined accurately enough to compute all orbital elements precisely. Possible improvements to this are discussed. Title: Multi-wavelength imaging system for the Dutch Open Telescope Authors: Bettonvil, Felix C.; Suetterlin, Peter; Hammerschlag, Robert H.; Jagers, Aswin P.; Rutten, Robert J. Bibcode: 2003SPIE.4853..306B Altcode: The Dutch Open Telescope (DOT) is an innovative solar telescope, completely open, on an open steel tower, without a vacuum system. The aim is long-duration high resolution imaging and in order to achieve this the DOT is equipped with a diffraction limited imaging system in combination with a data acquisition system designed for use with the speckle masking reconstruction technique for removing atmospheric aberrations. Currently the DOT is being equipped with a multi-wavelength system forming a high-resolution tomographic imager of magnetic fine structure, topology and dynamics in the photosphere and low- and high chromosphere. Finally the system will contain 6 channels: G-band (430.5 nm), Ca II H (K) (396.8 nm), H-α (656.3 nm), Ba II (455.4 nm), and two continuum channels (432 and 651 nm). Two channels are in full operation now and observations show that the DOT produces real diffraction limited movies (with 0.2" resolution) over hours in G-band (430.5 nm) and continuum (432 nm). Title: Large open telescope: size-upscaling from DOT to LOT Authors: Hammerschlag, Robert H.; Jaegers, Aswin P. L.; Bettonvil, Felix C. M. Bibcode: 2003SPIE.4853..294H Altcode: The design characteristics of a large open telescope (LOT) are: (i) an open tower with only pure translations of the platform under wind load; (ii) an open telescope construction with extremely stiff geometry and drives; (iii) simple optics with easy aligning and testing, but nevertheless suitable for large auxiliary equipment like spectrographs. Title: Dutch Open Telescope: status, results, prospects Authors: Rutten, Robert J.; Sütterlin, Peter; de Wijn, Alfred G.; Hammerschlag, Robert H.; Bettonvil, Felix C. M.; Hoogendoorn, Piet W.; Jägers, Aswin P. L. Bibcode: 2002ESASP.506..903R Altcode: 2002svco.conf..903R; 2002ESPM...10..903R The Dutch Open Telescope (DOT) on La Palma is a revolutionary telescope achieving high-resolution imaging of the solar surface. The DOT combines a pioneering open design at an excellent wind-swept site with image restoration through speckle interferometry. Its open principle is now followed in major solar-telescope projects elsewhere. In the past three years the DOT became the first solar telescope to regularly obtain 0.2" resolution in extended image sequences, i.e., reaching the diffraction limit of its 45-cm primary mirror. Our aim for 2003-2005 is to turn the DOT into a 0.2" tomographic mapper of the solar atmosphere with frequent partnership in international multi-telescope campaigns through student-serviced time allocation. After 2005 we aim to triple the DOT resolution to 0.07" by increasing the aperture to 140 cm and to renew the speckle cameras and the speckle pipeline in order to increase the field size and sequence duration appreciably. These upgrades will maintain the DOT's niche as a tomographic high-resolution mapper in the era when GREGOR, Solar-B and SDO set the stage. Title: Opening the Dutch Open Telescope Authors: Rutten, R. J.; de Wijn, A. G.; Sütterlin, P.; Bettonvil, F. C. M.; Hammerschlag, R. H. Bibcode: 2002ESASP.505..565R Altcode: 2002IAUCo.188..565R; 2002solm.conf..565R We hope to "open the DOT" to the international solar physics community as a facility for high-resolution tomography of the solar atmosphere. Our aim is to do so combining peer-review time allocation with service-mode operation in a "hands-on-telescope" education program bringing students to La Palma to assist in the observing and processing. The largest step needed is considerable speedup of the DOT speckle processing. Title: Proxy Magnetometry with the Dutch Open Telescope Authors: Rutten, R. J.; Hammerschlag, R. H.; Sütterlin, P.; Bettonvil, F. C. M. Bibcode: 2001ASPC..236...25R Altcode: 2001aspt.conf...25R No abstract at ADS Title: A Multi-Channel Speckle Imaging System for the DOT Authors: Sütterlin, P.; Hammerschlag, R. H.; Bettonvil, F. C. M.; Rutten, R. J.; Skomorovsky, V. I.; Domyshev, G. N. Bibcode: 2001ASPC..236..431S Altcode: 2001aspt.conf..431S No abstract at ADS Title: Solar Magnetometry with the Dutch Open Telescope Authors: Rutten, R.; Hammerschlag, R. H.; Sutterlin, P.; Bettonvil, F. C. M.; van der Zalm, E. B. J. Bibcode: 2000ESASP.463..611R Altcode: 2000sctc.proc..611R No abstract at ADS Title: The Dutch Open Telescope Authors: Rutten, R. J.; Hammerschlag, R. H.; Bettonvil, F. C. M. Bibcode: 1999ASPC..158...57R Altcode: 1999ssa..conf...57R No abstract at ADS Title: The Dutch Open Telescope at the Roque de los Muchachos Observatory Authors: Hammerschlag, Robert H.; Bettonvil, Felix C. M. Bibcode: 1998NewAR..42..485H Altcode: We briefly describe the Dutch Open Telescope, whose innovative design tries to get the most out of the good La Palma seeing. Title: De Dutch Open Telescope: nieuwe zonnentelescoop op La Palma. Authors: Rutten, R.; Hammerschlag, R.; Bettonvil, F. Bibcode: 1997Zenit..24..481R Altcode: No abstract at ADS Title: Video equipment for Meteor Observations: some Modern Technology Authors: Bettonvil, F. Bibcode: 1997pimo.conf...99B Altcode: No abstract at ADS Title: Dutch Open Telescope: Status and Prospects Authors: Rutten, R. J.; Hammerschlag, R. H.; Bettonvil, F. C. M. Bibcode: 1997ASPC..118..335R Altcode: 1997fasp.conf..335R The Dutch Open Telescope represents a new solar telescope concept. Being open rather than evacuated, it leads the way to large-aperture high resolution telescopes. It is now being installed on La Palma. Title: The daylight fireball over the North Sea, May 29, 1994, 9h32m±1m UT. Authors: Bettonvil, F.; Neijts, M.; Apeldoorn, B. Bibcode: 1994JIMO...22..173B Altcode: 1994WGN....22..173B No abstract at ADS Title: De Utrechtse open toren telescoop. Authors: Bettonvil, F. C. M.; Hammerschlag, R. H. Bibcode: 1993Zenit..20..327B Altcode: No abstract at ADS Title: Wat doen de Perseïden in 1993? Authors: Bettonvil, F.; Gloudemans, R. Bibcode: 1993Zenit..20..266B Altcode: No abstract at ADS Title: Orbits of meteorite producing fireballs: The Glanerbrug - A case study Authors: Jenniskens, Peter; Borovicka, Jiri; Betlem, Hans; Ter Kuile, Casper; Bettonvil, Felix; Heinlein, Dieter Bibcode: 1992A&A...255..373J Altcode: At 18:32:38 UT on April 7, 1990, a breccious L-LL type chondrite fell near Glanerbrug in the Netherlands. From visual observations of the meteor by 200 occasional observers, a heliocentric orbit is derived by several independent methods, including a new method using the slope of the meteor on the sky as seen from different locations. The orbit found has a relatively high inclination of 23 +/- 5 deg, adding weight to the high inclination tail of meteorite producing fireballs. The average value of i for this population matches that of the population of near-earth asteroids, but is significantly higher than that found for the possible meteorite producing fireballs registered in the Prairie Network and the Meteorite Observation and Recovery Project. Title: The Glanerbrug meteorite fall. Authors: Jenniskens, P.; Borovička, J.; Betlem, H.; Ter Kuile, C.; Bettonvil, F.; Heinlein, D. Bibcode: 1992PAICz..79.....J Altcode: The meteorite fall at Glanerbrug, at 18:32:38 UT on April 7, 1990, is described on the basis of 200 eye witness accounts of the associated meteor. Due to a favourable distribution of observing locations, the atmospheric trajectory can be reconstructed from several different approaches to the data. The orbit found has a relatively high inclination of 23±5 degrees, adding weight to the high inclination tail of the population distribution of meteorite dropping events. Title: De Glanerbrug, Nederlands vijfde meteoriet. Authors: Bettonvil, F. Bibcode: 1990Zenit..17..425B Altcode: No abstract at ADS Title: Perseiden 1989 vanuit Winterswijk en Heesch Authors: Bettonvil, Felix Bibcode: 1989Rad....11..112B Altcode: No abstract at ADS Title: Vuurbollen in april. Authors: Bettonvil, F. Bibcode: 1987Zenit..14..406B Altcode: No abstract at ADS Title: Orioniden 1987 te Vught Authors: Bettonvil, Felix Bibcode: 1987Rad.....9..100B Altcode: No abstract at ADS