Author name code: artzner ADS astronomy entries on 2022-09-14 author:"Artzner, Guy" ------------------------------------------------------------------------ Title: Coronographie interferéntielle pour la mission spatuale DARWIN: expérience de validation en laboratoire Authors: Ollivier, Marc; Mariotti, Jean-Marie; Brunaud, Jacqueline; Michel, Guy; Bouchareine, Patrick; Léger, Alain; Artzner, Guy; Malbet, Fabien; Puget, Pascal; Coudé du Foresto, Vincent; Mennesson, Bertrand Bibcode: 2018SPIE10570E..0PO Altcode: This paper, "Coronographie interferéntielle pour la mission spatuale DARWIN: expérience de validation en laboratoire," was presented as part of International Conference on Space Optics—ICSO 1997, held in Toulouse, France. Title: Time Evolution of the Altitude of an Observed Coronal Wave Authors: Delannée, C.; Artzner, G.; Schmieder, B.; Parenti, S. Bibcode: 2014SoPh..289.2565D Altcode: 2014SoPh..tmp...49D; 2013arXiv1310.5623D The nature of coronal wave fronts is intensely debated. They are observed in several wavelength bands and are frequently interpreted as magnetosonic waves propagating in the lower solar atmosphere. However, they can also be attributed to the line-of-sight projection of the edges of coronal mass ejections. Therefore, estimating the altitude of these features is crucial for deciding in favor of one of these two interpretations. We took advantage of a set of observations obtained from two different view directions by the EUVI instrument onboard the STEREO mission on 7 December 2007 to derive the time evolution of the altitude of a coronal wave front. We developed a new technique to compute the altitude of the coronal wave and found that the altitude increased during the initial 5 min and then slightly decreased back to the low corona. We interpret the evolution of the altitude as follows: the increase in the altitude of the wave front is linked to the rise of a bubble-like structure depending on whether it is a magnetosonic wave front or a CME in the initial phase. During the second phase, the observed brightness of the wave front was mixed with the brightening of the underlying magnetic structures as the emission from the wave front faded because the plasma became diluted with altitude. Title: A Multi-spacecraft View of a Giant Filament Eruption during 2009 September 26/27 Authors: Gosain, Sanjay; Schmieder, Brigitte; Artzner, Guy; Bogachev, Sergei; Török, Tibor Bibcode: 2012ApJ...761...25G Altcode: 2012arXiv1210.6686G We analyze multi-spacecraft observations of a giant filament eruption that occurred during 2009 September 26 and 27. The filament eruption was associated with a relatively slow coronal mass ejection. The filament consisted of a large and a small part, and both parts erupted nearly simultaneously. Here we focus on the eruption associated with the larger part of the filament. The STEREO satellites were separated by about 117° during this event, so we additionally used SoHO/EIT and CORONAS/TESIS observations as a third eye (Earth view) to aid our measurements. We measure the plane-of-sky trajectory of the filament as seen from STEREO-A and TESIS viewpoints. Using a simple trigonometric relation, we then use these measurements to estimate the true direction of propagation of the filament which allows us to derive the true R/R ⊙-time profile of the filament apex. Furthermore, we develop a new tomographic method that can potentially provide a more robust three-dimensional (3D) reconstruction by exploiting multiple simultaneous views. We apply this method also to investigate the 3D evolution of the top part of filament. We expect this method to be useful when SDO and STEREO observations are combined. We then analyze the kinematics of the eruptive filament during its rapid acceleration phase by fitting different functional forms to the height-time data derived from the two methods. We find that for both methods an exponential function fits the rise profile of the filament slightly better than parabolic or cubic functions. Finally, we confront these results with the predictions of theoretical eruption models. Title: A Technique for Removing Background Features in SECCHI - EUVI He II 304 Å Filtergrams: Application to the Filament Eruption of 22 May 2008 Authors: Artzner, G.; Gosain, S.; Schmieder, B. Bibcode: 2010SoPh..262..437A Altcode: 2010SoPh..tmp...41A; 2010SoPh..tmp...53A; 2010arXiv1001.4884A The STEREO mission has been providing a stereoscopic view of filament eruptions in the EUV. The clearest view during a filament eruption is seen in He II 304 Å observations. One of the main problems in visualizing filament dynamics in He II 304 Å is the strong background contrast due to surface features. We present a technique that removes background features and leaves behind only the filamentary structure, as seen by STEREO-A and -B. The technique uses a pair of STEREO He II 304 Å images observed simultaneously. The STEREO-B image is geometrically transformed to a STEREO-A view so that the background images appear similar. Filaments, being elevated structures, i.e., not lying on the same spherical surface as background features, do not appear similar in the transformed view. Thus, subtracting the two images cancels the background but leaves behind the filament structure. We apply this technique to study the dynamics of the filament-eruption event of 22 May 2008, which was observed by STEREO and followed by several ground-based observatories participating in the Joint Observing Programme (JOP 178). Title: A 3D view of eruptive filaments by STEREO Authors: Gosain, Sanjay; Schmieder, Brigitte; Venkatakrishnan, P.; Chandra, Ramesh; Artzner, Guy Bibcode: 2010cosp...38.2916G Altcode: 2010cosp.meet.2916G STEREO/SECHI/EUVI A and B observe different views of the eruption of a quiescent filament. We will concentrate on two events: (i) May 20 to 22, 2008 event (A and B separated by 52.4 degrees from each other), and (ii) September 25 to 26, 2009 event (A and B more than 100 degrees from each other. After using different techniques of reconstruction we obtained a 3 dimensional view of untwisted flux ropes in He II 304 Angstrom, with fine structures. The entire disappearance phase lasted more than ten hours. The filament evolved very slowly ( 5 km/s) from a dense structure with a thick spine into fine threads. Individual threads are seen to be oscillating and rising to an altitude of about 150 Mm with velocities of about 100 km/s. The plasma disappears by diffusion in the corona. Weak CME events are recorded by LASCO at the beginning of the disappearance. In this paper we shall present the dynamics of the filament eruptions as viewed in 3D by STEREO using different methods. We shall explore the causes and consequences of the filament disappearance. Title: 3D Evolution of a Filament Disappearance Event Observed by STEREO Authors: Gosain, S.; Schmieder, B.; Venkatakrishnan, P.; Chandra, R.; Artzner, G. Bibcode: 2009SoPh..259...13G Altcode: 2009arXiv0910.0786G A filament disappearance event was observed on 22 May 2008 during our recent campaign JOP 178. The filament, situated in the Southern Hemisphere, showed sinistral chirality consistent with the hemispheric rule. The event was well observed by several observatories, in particular by THEMIS. One day, before the disappearance, Hα observations showed up- and down-flows in adjacent locations along the filament, which suggest plasma motions along twisted flux rope. THEMIS and GONG observations show shearing photospheric motions leading to magnetic flux canceling around barbs. STEREO A, B spacecraft with separation angle 52.4°, showed quite different views of this untwisting flux rope in He II 304 Å images. Here, we reconstruct the three-dimensional geometry of the filament during its eruption phase using STEREO EUV He II 304 Å images and find that the filament was highly inclined to the solar normal. The He II 304 Å movies show individual threads, which oscillate and rise to an altitude of about 120 Mm with apparent velocities of about 100 km s−1 during the rapid evolution phase. Finally, as the flux rope expands into the corona, the filament disappears by becoming optically thin to undetectable levels. No CME was detected by STEREO, only a faint CME was recorded by LASCO at the beginning of the disappearance phase at 02:00 UT, which could be due to partial filament eruption. Further, STEREO Fe XII 195 Å images showed bright loops beneath the filament prior to the disappearance phase, suggesting magnetic reconnection below the flux rope. Title: Optique active et optique adaptative. Authors: Artzner, G. Bibcode: 2006LAstr.120..349A Altcode: No abstract at ADS Title: An atlas of solar events: 1996 2005 Authors: Artzner, G.; Auchère, F.; Delaboudinière, J. P.; Bougnet, M. Bibcode: 2006AdSpR..38..390A Altcode: Coronal mass ejections (CMEs) are observed in the plane of the sky in coronographic images. As the solar surface is masked by an occulting disk it is not clear whether halo CMEs are directed towards or away from the Earth. Observations of the solar corona on the solar disk by the extreme ultraviolet imaging telescope (EIT) on board the Solar Heliospheric Observatory SoHO can help to resolve this. Quasi-continuous observations of the solar corona were obtained from April 1997 up to the current date at a 12 min cadence in the coronal line of FeXII, as part of a “CME watch program”. At a slower 6 h cadence an additional synoptic program investigates the chromosphere and the corona at four different wavelengths. Large coronal solar events appear when viewing animations of the CME watch program. Fainter events do appear when viewing running difference animations of the CME watch program. When looking for additional spectral information from raw running differences of the synoptic program it is difficult to disentangle intrinsic solar events from the parasitic effect of the solar rotation. We constructed at www.ias.u-psud.fr/medoc/EIT/movies/ an atlas of more than 40,000 difference images from the synoptic programme, corrected for an average solar rotation, as well as more than 200,000 instantaneous and difference images from the CME watch program. We present case studies of specific events in order to investigate the source of darkenings or dimmings in difference images, due to the removal of emitting material, the presence of obscuring material or large changes in temperature. As the beneficial effect of correcting for the solar rotation vanishes at the solar limb, we do not investigate the case of prominence Doppler dimming. As a by-product of the atlas of solar events we obtain a number of quiet time sequences well suited to precisely measure the differential solar rotation by the apparent displacement of tracers. Title: EIT Observations of the 15 November 1999 Mercury Transit Authors: Auchère, F.; Artzner, G. E. Bibcode: 2004SoPh..219..217A Altcode: The Mercury transit of 15 November 1999 has been observed from space by the SOHO and TRACE spacecraft. We exploited the data recorded by EIT/SOHO to determine the stray-light level and the plate-scale of the instrument. The asymmetric distribution of stray light across the images is confirmed, but the absolute amount was found to be higher than previously estimated. The plate scale averaged over wavelengths was found to be 2.627±0.001 arc sec pixel−1, in excellent agreement with two previous and independent determinations. Title: EUVI: the STEREO-SECCHI extreme ultraviolet imager Authors: Wuelser, Jean-Pierre; Lemen, James R.; Tarbell, Theodore D.; Wolfson, C. J.; Cannon, Joseph C.; Carpenter, Brock A.; Duncan, Dexter W.; Gradwohl, Glenn S.; Meyer, Syndie B.; Moore, Augustus S.; Navarro, Rosemarie L.; Pearson, J. D.; Rossi, George R.; Springer, Larry A.; Howard, Russell A.; Moses, John D.; Newmark, Jeffrey S.; Delaboudiniere, Jean-Pierre; Artzner, Guy E.; Auchere, Frederic; Bougnet, Marie; Bouyries, Philippe; Bridou, Francoise; Clotaire, Jean-Yves; Colas, Gerard; Delmotte, Franck; Jerome, Arnaud; Lamare, Michel; Mercier, Raymond; Mullot, Michel; Ravet, Marie-Francoise; Song, Xueyan; Bothmer, Volker; Deutsch, Werner Bibcode: 2004SPIE.5171..111W Altcode: The Extreme Ultraviolet Imager (EUVI) is part of the SECCHI instrument suite currently being developed for the NASA STEREO mission. Identical EUVI telescopes on the two STEREO spacecraft will study the structure and evolution of the solar corona in three dimensions, and specifically focus on the initiation and early evolution of coronal mass ejections (CMEs). The EUVI telescope is being developed at the Lockheed Martin Solar and Astrophysics Lab. The SECCHI investigation is led by the Naval Research Lab. The EUVI"s 2048 x 2048 pixel detectors have a field of view out to 1.7 solar radii, and observe in four spectral channels that span the 0.1 to 20 MK temperature range. In addition to its view from two vantage points, the EUVI will provide a substantial improvement in image resolution and image cadence over its predecessor SOHO-EIT, while complying with the more restricted mass, power, and volume allocations on the STEREO mission. Title: An atlas of solar events: 1997-2004 Authors: Artzner, G.; Auchère, F.; Delaboudinière, J. P.; Bougnet, M. Bibcode: 2004cosp...35.2494A Altcode: 2004cosp.meet.2494A Coronal mass ejections (CMEs) are observed in the plane of the sky from coronographic images. As the solar surface is then masked by an occulting disk, it is not clear wether halo CMEs are directed towards the Earth or in the opposite direction. Observations of the solar corona on the solar disk from the Extreme Ultraviolet Imaging Telescope EIT on board the Solar Heliospheric Observatory SoHO do help in order to make a choice. Quasi-continuous observations of the corona of the Sun have been therefore obtained from april 1997 up to now at a twelve minute cadence in the coronal line of FeXII, as a CME watch program. At a slower six hours cadence an additional synoptic program investigates the chromosphere and the corona at four different wavelengths. Large coronal solar events appear when viewing animations of the CME watch program. Fainter events do appear when viewing running difference animations of the CME watch program. When looking for additional spectral information from raw running differences of the synoptic program it is difficult to disentangle intrinsic solar events from the parasitic effect of the solar rotation. We constructed from the synoptic program observations an atlas of more than 20 000 difference images corrected for an average solar rotation. We present case studies of specific events in order to investigate the source of darkenings in difference images, either removal of emitting material, interposition of obscuring material or large changes of temperature. Statistics of brigtenings and darkenings along solar cycle 23 are presented. We speculate about future observations from the STEREO mission in order to obtain better diagnostics about darkenings. As a by product of the atlas of solar events we obtain a number of quiet time sequences well suited in order to precisely measure the differnetial solar rotation by the apparent displacement of tracers. Title: Photon sieves as EUV telescopes for Solar Orbiter Authors: Artzner, Guy E.; Delaboudiniere, Jean Pierre; Song, Xueyan Bibcode: 2003SPIE.4853..158A Altcode: We elaborate about obtaining images of the solar disc and of the solar corona at discrete wavelengths along the EUV emission solar spectrum on board the Solar Orbiter spacecraft. Refractive optics cannot be used. The thermal load is twenty five times higher than on a near Earth orbit. As on one side the efficiency of a stenopeic device is too low, and as on the other side mirrors exposed directly to the light and to the particles emitted by the Sun may severely degrade during time, we investigated using the EUV analog of a Fresnel lens, i.e. a photon sieve. An opaque self supporting flat piece of heat resistant metal let the solar light shine through a large numbers of a few thousand holes properly designed in positions and diameters in order to obtain constructive interferences at some focus. We report about practical experiments in the visible. Title: MAGRITTE / SPECTRE : the Solar Atmospheric Imaging Assembly (AIA) aboard the Solar Dynamics Observatory Authors: Rochus, P.; Defise, J. M.; Halain, J. P.; Mazy, E.; Jamar, C.; Clette, F.; Cugnon, P.; Berghmans, D.; Hochedez, J. F.; Delaboudiniere, J. P.; Artzner, G.; Auchere, F.; Mercier, R.; Ravet, M. F.; Delmotte, M.; Idir, M.; Fineschi, S.; Antonucci, E.; Harrison, R. A.; Howard, R. A.; Moses, J. D.; Newmark, J. S. Bibcode: 2002AGUFMSH21C..05R Altcode: The Solar Atmospheric Imaging Assembly (AIA) aboard the Solar Dynamics Observatory will characterize the dynamical evolution of the solar plasma from the chromosphere to the corona, and will follow the connection of plasma dynamics with magnetic activity throughout the solar atmosphere. The AIA consists of 7 high resolution imaging telescopes in the following spectral bandpasses: 1215 \x8F Ly-a, 304 \x8F He II, 629 \x8F OV, 465 \x8F Ne VII, 195 \x8F Fe XII (includes Fe XXIV), 284 \x8F Fe XV, and 335 \x8F Fe XVI. The telescopes are grouped by instrumental approach: the Magritte Filtergraphs (R. Magritte, famous 20th Century Belgian Surrealistic Artist), five multilayer EUV channels with bandpasses ranging from 195 to 1216 \x8F, and the SPECTRE Spectroheliograph with one soft-EUV channel at OV 629 \x8F. They will be simultaneously operated with a 10-second imaging cadence. These two instruments, the electronic boxes and two redundant Guide Telescopes (GT) constitute the AIA suite. They will be mounted and coaligned on a dedicated common optical bench. The GTs will provide pointing jitter information to the whole SHARPP assembly. This poster presents the selected technologies, the different challenges, the trade-offs to be made in phase A, and the model philosophy. From a scientific viewpoint, the unique combination high temporal and spatial resolutions with the simultaneous multi-channel capability will allow Magritte/SPECTRE to explore new domains in the dynamics of the solar atmosphere, in particular the fast small-scale phenomena. We show how the spectral channels of the different instruments were derived to fulfill the AIA scientific objectives, and we outline how this imager array will address key science issues, like the transition region and coronal waves or flare precursors, in coordination with other SDO experiments. We finally describe the real-time solar monitoring products that will be made available for space-weather forecasting applications. Title: Transition region quiet sun velocity field evolution Authors: Lemaire, P.; Artzner, G.; Vial, J. -C.; Curdt, W.; Schühle, U.; Wilhelm, K. Bibcode: 2002AdSpR..30..487L Altcode: The UV/EUV SUMER spectrometer aboard SOHO can record profiles of lines emitted by elements at different stages of ionization corresponding to several temperatures within the transition region temperature range. During the solar cycle minimum in July 1996, we were able to observe the quiet Sun during five consecutive days. From the line positions we have determined the velocity fields and follow their time variations at different temperatures in the transition region. The line intensity maps are used to separate supergranular cells and network and they allow to compare the behaviors of the velocity fields evolution in the two structures. The results are critically analyzed and discussed. Title: Nulling interferometry for the DARWIN mission: experimental demonstration of the concept in the thermal infrared with high levels of rejection Authors: Ollivier, Marc; Mariotti, Jean-Marie; Sekulic, Predrag; Michel, Guy; Leger, Alain M.; Bouchareine, Patrick; Brunaud, Jacqueline; Coudé du Foresto, Vincent; Mennesson, Bertrand P.; Borde, Pascal J.; Amy-Klein, A.; Vanlerberghe, A.; Lagage, Pierre-Olivier; Artzner, Guy E.; Malbet, Fabien Bibcode: 2000SPIE.4006..354O Altcode: Present projects of space interferometers dedicated to the detection and analysis of extrasolar planets (DARWIN in Europe, TPF in the United States) are based on the nulling interferometry concept. This concept has been proposed by Bracewell in 1978 but has never been demonstrated with high values of rejection, in the thermal infrared range, where the planet detection should be performed (6 - 18 micrometers ). We have thus built a two-beam laboratory interferometer to validate this concept in a monochromatic case (at 10 micrometers ). The keypoint of our interferometer is the use of optical filtering by pinhole and optical fibers to clean the interfering beams. We present in this paper the principle of the experimental setup, its realization, and the first measurements of rejection it allowed. We also present the future developments of this interferometer. Title: In-Flight Determination of the Plate Scale of the Extreme-Ultraviolet Imaging Telescope Authors: Auchère, F.; DeForest, C. E.; Artzner, G. Bibcode: 2000ApJ...529L.115A Altcode: Using simultaneous observations of the Michelson Doppler Imager and Extreme-Ultraviolet Imaging Telescope (EIT) on board the Solar and Heliospheric Observatory spacecraft, we determined in flight the plate scale of the EIT. We found a value of 2.629"+/-0.001" pixel-1, in fair agreement with the 2.627"+/-0.001" pixel-1 value deduced from recent laboratory measurements of the focal length and much higher by 7 σ than the 2.622" pixel-1 value of the preflight calibrations. The plate scale is found to be constant across the field of view, confirming the negligible distortion level predicted by the theoretical models of the EIT. Furthermore, the 2 σ difference between our results and the latest laboratory measurements, although statistically small, may confirm a recent work suggesting that the solar photospheric radius may be 0.5 Mm lower than the classically adopted value of 695.99 Mm. Title: In Flight Determination of the Plate Scale of the EIT Authors: Auchere, F.; DeForest, C. E.; Artzner, G. Bibcode: 1999astro.ph.12213A Altcode: Using simultaneous observations of the MDI and EIT instruments on board the SoHO spacecraft, we determined in flight the plate scale of the EIT. We found a value of 2.629+-0.001 arc seconds per pixel, in fair agreement with the 2.627+-0.001 arc seconds per pixel value deduced from recent laboratory measurements of the focal length, and much higher by 7 sigma than the 2.622 arc seconds per pixel value of the pre-flight calibrations. The plate scale is found to be constant across the field of view, confirming the negligible distortion level predicted by the theoretical models of the EIT. Furthermore, the 2 sigma difference between our results and the latest laboratory measurements, although statistically small, may confirm a recent work suggesting that the solar photospheric radius may be 0.5 Mm lower than the classically adopted value of 695.99 Mm. Title: Spécial éclipse 11 aou^t 1999 - bilan. Authors: Laurent, M.; Weulersse, P.; Delahaye, F.; Gredin, E.; Gredin, P.; Roy, M.; Roy, H.; Arioli, H.; Boust, D.; Meeus, J.; Guillermier, P.; Artzner, G. Bibcode: 1999LAstr.113..340L Altcode: No abstract at ADS Title: An Eruptive Flare Observed by TRACE as a Test for the Magnetic Authors: Aulaneir, G.; Deluca, E. E.; Golub, L.; Artzner, Guy; Sabine Coquillart; Hochedez, Jean-Francois; Delaboudinier, Jean-Pierre Bibcode: 1999ESASP.446..131A Altcode: 1999soho....8..131A No abstract at ADS Title: Equivalent focal length measurements Authors: Artzner, Guy E.; Auchere, Frederic; Delaboudiniere, Jean-Pierre; Hochedez, Jean-Francois E. Bibcode: 1999SPIE.3737...32A Altcode: Converting linear coordinates in the plane of the detector of an astronomical instrument to celestial coordinates involves in principle the equivalent focal length of the instrument. However, most methods in astrometry manage to reduce observations in a global manner without actually measuring a focal length. We point out a case for solar space observations where the long term stability of angular distance measurements is better than the ground calibration of the angular value of a pixel. We report and discuss this ground calibration. Title: Nulling Interferometry for the DARWIN Mission - Laboratory Demonstration Experiment Authors: Ollivier, M.; Léger, A.; Sekulic, C. Anceau. P.; Brunaud, J.; Artzner, G.; Mariotti, J. -M.; Michel, G.; Coudé du Foresto, V.; Mennesson, B.; Bouchareine, P.; Lépine, T.; Malbet, F. Bibcode: 1999ASPC..194..443O Altcode: 1999wfoi.conf..443O The present projects of space interferometers dedicated to the detection and analysis of extrasolar planets (DARWIN/IRSI in Europe, TPF in the United States) are based on the nulling interferometry concept (interferometrical coronography). This concept has been proposed by Bracewell in 1979 but has never been demonstrated, with high values of rejection, in the thermal infrared range where planet detection should be performed (6-18 microns). We have thus built a two-beam laboratory interferometer to validate this concept in a monochromatic case (CO2 laser). We present the principle of the experimental setup, its realisation, its sub-systems and their servo-control. We present also the first results we got with this interferometer. Title: Observations of Coronal Structures Above an Active Region by EIT and Implications for Coronal Energy Deposition Authors: Neupert, W. M.; Newmark, J.; Delaboudinière, J. -P.; Thompson, B. J.; Catura, R. C.; Moses, J. D.; Gurman, J. B.; Portier-Fozzani, F.; Gabriel, A. H.; Artzner, G.; Clette, F.; Cugnon, P.; Maucherat, A. J.; Defise, J. M.; Jamar, C.; Rochus, P.; Dere, K. P.; Howard, R. A.; Michels, D. J.; Freeland, S.; Lemen, J. R.; Stern, R. A. Bibcode: 1998SoPh..183..305N Altcode: Solar EUV images recorded by the EUV Imaging Telescope (EIT) on SOHO have been used to evaluate temperature and density as a function of position in two largescale features in the corona observed in the temperature range of 1.0-2.0 MK. Such observations permit estimates of longitudinal temperature gradients (if present) in the corona and, consequently, estimates of thermal conduction and radiative losses as a function of position in the features. We examine two relatively cool features as recorded in EIT's Fe ix/x (171 Å) and Fe xii (195 Å) bands in a decaying active region. The first is a long-lived loop-like feature with one leg, ending in the active region, much more prominent than one or more distant footpoints assumed to be rooted in regions of weakly enhanced field. The other is a near-radial feature, observed at the West limb, which may be either the base of a very high loop or the base of a helmet streamer. We evaluate energy requirements to support a steady-state energy balance in these features and find in both instances that downward thermal conductive losses (at heights above the transition region) are inadequate to support local radiative losses, which are the predominant loss mechanism. The requirement that a coronal energy deposition rate proportional to the square of the ambient electron density (or pressure) is present in these cool coronal features provides an additional constraint on coronal heating mechanisms. Title: The prolate solar chromosphere Authors: Auchere, F.; Boulade, S.; Koutchmy, S.; Smartt, R. N.; Delaboudiniere, J. P.; Georgakilas, A.; Gurman, J. B.; Artzner, G. E. Bibcode: 1998A&A...336L..57A Altcode: We present a comparative analysis of the chromospheric solar limb prolateness, using strictly simultaneous H_alpha ground-based observations and Heriptsize{II} space-based observations. The typical prolateness is found to be Delta D/D=5.5*E(-3) in Heriptsize{II} and 1.2*E(-3) in H_alpha . The first measurements in the 30.4 nm Heriptsize{II} line over a period of two years, as well as coronal data, are discussed to explore further the origin of the prolateness and its possible consequences. Title: Aspherical wavefront measurements: Shack-Hartmann numerical and practical experiments Authors: Artzner, Guy Bibcode: 1998PApOp...7..435A Altcode: No abstract at ADS Title: EIT Observations of the Extreme Ultraviolet Sun Authors: Moses, D.; Clette, F.; Delaboudinière, J. -P.; Artzner, G. E.; Bougnet, M.; Brunaud, J.; Carabetian, C.; Gabriel, A. H.; Hochedez, J. F.; Millier, F.; Song, X. Y.; Au, B.; Dere, K. P.; Howard, R. A.; Kreplin, R.; Michels, D. J.; Defise, J. M.; Jamar, C.; Rochus, P.; Chauvineau, J. P.; Marioge, J. P.; Catura, R. C.; Lemen, J. R.; Shing, L.; Stern, R. A.; Gurman, J. B.; Neupert, W. M.; Newmark, J.; Thompson, B.; Maucherat, A.; Portier-Fozzani, F.; Berghmans, D.; Cugnon, P.; Van Dessel, E. L.; Gabryl, J. R. Bibcode: 1997SoPh..175..571M Altcode: The Extreme Ultraviolet Imaging Telescope (EIT) on board the SOHO spacecraft has been operational since 2 January 1996. EIT observes the Sun over a 45 x 45 arc min field of view in four emission line groups: Feix, x, Fexii, Fexv, and Heii. A post-launch determination of the instrument flatfield, the instrument scattering function, and the instrument aging were necessary for the reduction and analysis of the data. The observed structures and their evolution in each of the four EUV bandpasses are characteristic of the peak emission temperature of the line(s) chosen for that bandpass. Reports on the initial results of a variety of analysis projects demonstrate the range of investigations now underway: EIT provides new observations of the corona in the temperature range of 1 to 2 MK. Temperature studies of the large-scale coronal features extend previous coronagraph work with low-noise temperature maps. Temperatures of radial, extended, plume-like structures in both the polar coronal hole and in a low latitude decaying active region were found to be cooler than the surrounding material. Active region loops were investigated in detail and found to be isothermal for the low loops but hottest at the loop tops for the large loops. Title: EIT and LASCO Observations of the Initiation of a Coronal Mass Ejection Authors: Dere, K. P.; Brueckner, G. E.; Howard, R. A.; Koomen, M. J.; Korendyke, C. M.; Kreplin, R. W.; Michels, D. J.; Moses, J. D.; Moulton, N. E.; Socker, D. G.; St. Cyr, O. C.; Delaboudinière, J. P.; Artzner, G. E.; Brunaud, J.; Gabriel, A. H.; Hochedez, J. F.; Millier, F.; Song, X. Y.; Chauvineau, J. P.; Marioge, J. P.; Defise, J. M.; Jamar, C.; Rochus, P.; Catura, R. C.; Lemen, J. R.; Gurman, J. B.; Neupert, W.; Clette, F.; Cugnon, P.; Van Dessel, E. L.; Lamy, P. L.; Llebaria, A.; Schwenn, R.; Simnett, G. M. Bibcode: 1997SoPh..175..601D Altcode: We present the first observations of the initiation of a coronal mass ejection (CME) seen on the disk of the Sun. Observations with the EIT experiment on SOHO show that the CME began in a small volume and was initially associated with slow motions of prominence material and a small brightening at one end of the prominence. Shortly afterward, the prominence was accelerated to about 100 km s-1 and was preceded by a bright loop-like structure, which surrounded an emission void, that traveled out into the corona at a velocity of 200-400 km s-1. These three components, the prominence, the dark void, and the bright loops are typical of CMEs when seen at distance in the corona and here are shown to be present at the earliest stages of the CME. The event was later observed to traverse the LASCO coronagraphs fields of view from 1.1 to 30 R⊙. Of particular interest is the fact that this large-scale event, spanning as much as 70 deg in latitude, originated in a volume with dimensions of roughly 35" (2.5 x 104 km). Further, a disturbance that propagated across the disk and a chain of activity near the limb may also be associated with this event as well as a considerable degree of activity near the west limb. Title: Association of Extreme-Ultraviolet Imaging Telescope (EIT) Polar Plumes with Mixed-Polarity Magnetic Network Authors: Wang, Y. -M.; Sheeley, N. R.; Dere, K. P.; Duffin, R. T.; Howard, R. A.; Michels, D. J.; Moses, J. D.; Harvey, J. W.; Branston, D. D.; Delaboudinière, J. -P.; Artzner, G. E.; Hochedez, J. F.; Defise, J. M.; Catura, R. C.; Lemen, J. R.; Gurman, J. B.; Neupert, W. M.; Newmark, J.; Thompson, B.; Maucherat, A.; Clette, F. Bibcode: 1997ApJ...484L..75W Altcode: SOHO EIT spectroheliograms showing the polar coronal holes during the present sunspot minimum are compared with National Solar Observatory (Kitt Peak) magnetograms taken in Fe I λ8688 and Ca II λ8542. The chromospheric λ8542 magnetograms, obtained on a routine, near-daily basis since 1996 June, reveal the Sun's strong polar fields with remarkable clarity. We find that the Fe IX λ171 polar plumes occur where minority-polarity flux is in contact with flux of the dominant polarity inside each polar hole. Moreover, the locations of ``plume haze'' coincide approximately with the patterns of brightened He II λ304 network within the coronal hole. The observations appear to be consistent with mechanisms of plume formation involving magnetic reconnection between unipolar flux concentrations and nearby bipoles. The fact that minority-polarity fields constitute only a small fraction of the total magnetic flux within the polar holes suggests that plumes are not the main source of the high-speed polar wind. Title: Observations of Coronal Features by EIT above an Active Region by EIT and Implications for Coronal Heating Authors: Neupert, W. M.; Newmark, J.; Thompson, B. J.; Catura, R.; Moses, J. D.; Portier-Fozzani, F.; Delaboudiniere, J. P.; Gabriel, A.; Artzner, G.; Clette, F.; Cugnon, P.; Maucherat, A.; Defise, J. M.; Jamar, C.; Rochus, P.; Howard, R.; Michels, D.; Dere, K.; Freeland, S.; Lemen, J.; Stern, R.; Gurman, J. Bibcode: 1997SPD....28.0115N Altcode: 1997BAAS...29..881N The EUV Imaging Telescope (EIT) on the SOHO provides the capability for multi-wavelength imaging of the corona in four spectral bands, centered at 171, 195, 284, and 304 Angstroms, using multilayer telescope technology. These bands encompass coronal temperatures from 1 MK to 2.5 MK as well as the upper chromosphere, at about 60,000 K. In particular, nearly simultaneous imaging in the 171 and 195 Angstrom bands, the former including major Fe IX and Fe X emission lines, the latter including a strong Fe XII line, provides a capability to infer the morphology and characteristics of the corona at temperatures of 1.0 - 1.7 MK. We have examined the corona in this temperature range over an active region observed from SOHO from May - September, 1996 and find that low-lying loops (below a density scale height of 75,000 km, characteristic of Fe X) vary little in brightness and temperature along their length. For features extending to greater heights, however, both brightness gradients and temperature gradients are observed. Preliminary analysis of the observations when the region was on the West limb on September 30 indicates a small positive temperature gradient of approximately 0.5 K/km in one loop system that extended above 100,000 km. On the other hand, a nearly radial feature extending to the edge of the EIT FOV was isothermal or had at most a slight negative temperature gradient. Such measurements may have application to the modeling of coronal loops and streamers and the processes of coronal heating and solar wind acceleration. Title: Imaging the solar corona in the EUV Authors: Delaboudiniere, J. -P.; Stern, R. A.; Maucherat, A.; Portier-Fozzani, F.; Neupert, W. M.; Gurman, J. B.; Catura, R. C.; Lemen, J. R.; Shing, L.; Artzner, G. E.; Brunaud, J.; Gabriel, A. H.; Michels, D. J.; Moses, J. D.; Au, B.; Dere, K. P.; Howard, R. A.; Kreplin, R.; Defise, J. M.; Jamar, C.; Rochus, P.; Chauvineau, J. P.; Marioge, J. P.; Clette, F.; Cugnon, P.; van Dessel, E. L. Bibcode: 1997AdSpR..20.2231D Altcode: The SOHO (SOlar and Heliospheric Observatory) satellite was launched on December 2nd 1995. After arriving at the Earth-Sun (L1) Lagrangian point on February 14th 1996, it began to continuously observe the Sun. As one of the instruments onboard SOHO, the EIT (Extreme ultraviolet Imaging Telescope) images the Sun's corona in 4 EUV wavelengths. The He II filter at 304 A˚ images the chromosphere and the base of the transition region at a temperature of 5 - 8 x 10^4 K; the Fe IX-X filter at 171 A˚ images the corona at a temperature of ~ 1.3 x 10^6 K; the Fe XII filter at 195 A˚ images the quiet corona outside coronal holes at a temperature of ~ 1.6 x 10^6 K; and the Fe XV filter at 284 A˚ images active regions with a temperature of ~ 2.0 x 10^6 K. About 5000 images have been obtained up to the present. In this paper, we describe also some aspects of the telescope and the detector performance for application in the observations. Images and movies of all the wavelengths allow a look at different phenomena present in the Sun's corona, and in particular, magnetic field reconnection. Title: First Results from EIT Authors: Clette, F.; Delaboudiniere, J. -P.; Artzner, G. E.; Brunaud, J.; Gabriel, A. H.; Hochedez, J. -F.; Millier, F.; Song, X. Y.; Au, B.; Dere, K. P.; Howard, R. A.; Kreplin, R.; Michels, D. J.; Moses, J. D.; Defise, J. -M.; Jamar, C.; Rochus, P.; Chauvineau, J. -P.; Marioge, J. -P.; Catura, R. C.; Lemen, J. R.; Shing, L.; Stern, R. A.; Gurman, J. B.; Neupert, W. M.; Maucherat, A.; Cugnon, P.; van Dessel, E. L. Bibcode: 1997ASPC..118..268C Altcode: 1997fasp.conf..268C The Extreme-UV Imaging telescope has already produced more than 15000 wide-field images of the corona and transition region, on the disk and up to 1.5R_⊙ above the limb, with a pixel size of 2.6\arcsec. By using four different emission lines, it provides the global temperature distribution in the quiet corona, in the range 0.5 to 3*E(6) K. Its excellent sensitivity and wide dynamic range allow unprecedented views of low emission features, even inside coronal holes. Those so-called ``quiet'' regions actually display a wide range of dynamical phenomena, in particular at small spatial scales and at time scales going down to only a few seconds, as revealed by all EIT time sequences of full- or partial-field images. The initial results presented here demonstrate the importance of this wide-field imaging experiment for a good coordination between SOHO and ground-based solar telescopes, as well as for science planning. Title: Observations of the South coronal hole from EIT and YOHKOH Authors: Handy, B. N.; Catura, R.; Freeland, S.; Lemen, J.; Stern, R.; Gurman, J. B.; Delaboudiniere, J. P.; Artzner, G.; Gabriel, A.; Maucherat, A.; Defise, J. M.; Jamar, C.; Rochus, P.; Clette, F.; Cugnon, P.; Howard, R.; Michels, D.; Moses, J. D.; Dere, K.; Cyr, O. C. St.; Catura, R.; Freeland, S.; Lemen, J.; Stern, R.; Neupert, W.; Einfalt, E.; Newmark, J. Bibcode: 1996AAS...188.0206H Altcode: 1996BAAS...28..821H The Extreme ultraviolet Imaging Telescope (EIT) on board the SOHO spacecraft is capable of studying solar transition region, chomospheric and coronal plasmas over bandpasses optimized for He II 304 Angstroms (0.08 MK), Fe IX/X 171, 173 Angstroms (0.8 - 1.0 MK), Fe XII 195 Angstroms (1.5 MK), and Fe XV 284 Angstroms (2.0 - 2.5 MK) with 2.5 arcsecond spatial resolution. This telescope in concert with the Yohkoh/SXT instrument allows us to simultaneously observe solar structures at temperatures ranging from less than 0.1MK in the transition region to over 3MK in the solar corona. EIT has had several opportunities to observe the South coronal hole with high spatial and temporal resolution. We compare observations from EIT and SXT with an eye towards correlating temporal variations over the range of wavelengths, activity of polar crown filament systems and relating large-scale morphology of the X-ray corona to the transition region in He II. Title: There's No Such Thing as the Quiet Sun: EUV Movies from SOHO Authors: Gurman, J. B.; Delaboudiniere, J. P.; Artzner, G.; Gabriel, A.; Maucherat, A.; Defise, J. M.; Jamar, C.; Rochus, P.; Clette, F.; Cugnon, P.; Howard, R.; Michels, D.; Moses, J. D.; Dere, K.; Cyr, O. C. St.; Catura, R.; Freeland, S.; Lemen, J.; Stern, R.; Neupert, W.; Einfalt, E.; Newmark, J. Bibcode: 1996AAS...188.3718G Altcode: 1996BAAS...28..880G We present unique time series of high-resolution solar images from the normal-incidence Extreme ultraviolet Imaging Telescope (EIT) on board the SOHO spacecraft. With a pixel scale of 2.6 arc sec and a detector dynamic range of > 10(4) , the EIT can be used to study the dynamics of chromospheric and coronal features in multilayer bandpasses optimized for He II 304 Angstroms (0.08 MK), Fe IX/X 171, 173 Angstroms (0.8 - 1.0 MK), Fe XII 195 Angstroms (1.5 MK), and Fe XV 284 Angstroms (2.0 - 2.5 MK). Among the most striking features of the digital movies we will display are: the dynamic nature of small-scale loop features in the polar coronal holes, the constant activity of the polar crown filament systems, the locations of the bases of polar plumes, the presence of dark (scattering) filament material in the coronal emission line images, and the evolution of a unique, linear, dark feature in a young active region. The latter feature is suggestive of the ``coronal void'' observed in the electron scattering corona by Macqueen et al./ (1983). Title: Observations of the south coronal hole from EIT and Yohkoh. Authors: Handy, B. N.; Catura, R.; Freeland, S.; Lemen, J.; Stern, R.; Gurman, J. B.; Delaboudinière, J. P.; Artzner, G.; Gabriel, A.; Maucherat, A.; Defise, J. M.; Jamar, C.; Rochus, P.; Clette, F.; Cugnon, P.; Howard, R.; Michels, D.; Moses, J. D.; Dere, K.; St. Cyr, O. C.; Neupert, W.; Einfalt, E.; Newmark, J. Bibcode: 1996BAAS...28Q.821H Altcode: No abstract at ADS Title: EIT: Extreme-Ultraviolet Imaging Telescope for the SOHO Mission Authors: Delaboudinière, J. -P.; Artzner, G. E.; Brunaud, J.; Gabriel, A. H.; Hochedez, J. F.; Millier, F.; Song, X. Y.; Au, B.; Dere, K. P.; Howard, R. A.; Kreplin, R.; Michels, D. J.; Moses, J. D.; Defise, J. M.; Jamar, C.; Rochus, P.; Chauvineau, J. P.; Marioge, J. P.; Catura, R. C.; Lemen, J. R.; Shing, L.; Stern, R. A.; Gurman, J. B.; Neupert, W. M.; Maucherat, A.; Clette, F.; Cugnon, P.; Van Dessel, E. L. Bibcode: 1995SoPh..162..291D Altcode: The Extreme-ultraviolet Imaging Telescope (EIT) will provide wide-field images of the corona and transition region on the solar disc and up to 1.5 R⊙ above the solar limb. Its normal incidence multilayer-coated optics will select spectral emission lines from Fe IX (171 å), Fe XII (195 å), Fe XV (284 å), and He II (304 å) to provide sensitive temperature diagnostics in the range from 6 × 104 K to 3 × 106 K. The telescope has a 45 x 45 arcmin field of view and 2.6 arcsec pixels which will provide approximately 5-arcsec spatial resolution. The EIT will probe the coronal plasma on a global scale, as well as the underlying cooler and turbulent atmosphere, providing the basis for comparative analyses with observations from both the ground and other SOHO instruments. This paper presents details of the EIT instrumentation, its performance and operating modes. Title: Calibration of the EIT instrument for the SOHO mission Authors: Defise, Jean-Marc; Song, Xueyan Y.; Delaboudiniere, Jean-Pierre; Artzner, Guy E.; Carabetian, Charles; Hochedez, Jean-Francois E.; Brunaud, Jacqueline; Moses, John D.; Catura, Richard C.; Clette, Frederic; Maucherat, Andre J. Bibcode: 1995SPIE.2517...29D Altcode: Optical characteristics in the wavelength range 15 - 75 nm of the EUV imaging telescope to be launched soon on the SOHO mission are discussed. Bandpasses and photometric sensitivity of the multilayered optics telescope have been measured by a dedicated synchrotron light source at Orsay, France. Title: Fabrication and optical characteristics of microlens arrays engraved in photoresist coatings Authors: Gex, Francoise; Roblin, Gerard; Artzner, Guy E.; Bernstein, L.; Horville, David; Serpette, V. Bibcode: 1993SPIE.1781..287G Altcode: We have developed a technique for fabricating microlens arrays by engraving photoresist coatings. These microlens arrays are designed for astronomical applications for atmospheric wavefront sensors. First, we describe the apparatus and the manufacturing process. Second, we review the characteristics of the different photoresist types used in this process. Third, we report on the different optical testing methods to measure the microlens' performances. Then we deduce the several inherent advantages and limitations of this method. Fourth, we show how to produce monolithic arrays using ion beam milling with photoresist microlens arrays as a pattern and we demonstrate how these arrays can improve upon the performances of photoresist arrays. Title: Towards a dark matter experiment: performance of a 24g sapphire bolometer Authors: de Marcillac, P.; Coron, N.; Artzner, G.; Leblanc, J.; Torre, J. P.; Goldbach, C.; Nollez, G.; Vidal-Madjar, A.; Mangin, J. Bibcode: 1992daec.conf..403D Altcode: 1992daec.conf..403M I review here the debate on the nature of compact groups of galaxies: are the compact groups catalogued by Hickson physically dense systems or are they caused by chance alignments within larger systems? Results of recent N-body simulations of loose groups are analyzed, showing that only 10% of compact configurations seen in projection are three dimensional dense systems (of which roughly half are bound), whereas the remaining 90% are one dimensional chance alignments. Moreover, these chance alignments turn out to be binary-rich (with a small fraction of triplets too). The arguments reviewed here and these last two results suggest that rather than being dense quartets and quintets, most compact groups are binary-rich chance alignments within larger systems, thus providing a natural explanation to the high level of physical interactions seen in compact groups. Moreover, it is suggested that the most distant compact groups may represent the bright-ends of rich evolved clusters. Title: Solar corona synoptic observations from SOHO with an Extreme Ultraviolet Imaging Telescope. Authors: Delaboudinière, J. P.; Gabriel, A. H.; Artzner, G. E.; Dere, K.; Howard, R.; Michels, D.; Catura, R.; Lemen, J.; Stern, R.; Gurman, J.; Neupert, W.; Cugnon, P.; Koeckelenbergh, A.; van Dessel, E. L.; Jamar, C.; Maucherat, A. Bibcode: 1992ESASP.348...21D Altcode: 1992cscl.work...21D The major scientific objective of the EUV Imaging Telescope (EIT) is to study the evolution of coronal structure over a wide range of spatial and temporal scales and temperatures. A second strategic objective is to provide full disk synoptic maps of the global corona to aid in unifying SOHO (Solar and Heliospheric Observatory)/Cluster investigations. EIT will also provide images to support the planning of detailed spectroscopic investigations by the CDS (Coronal Diagnostic Spectrometer) and SUMER spectrometers in SOHO. EIT observations will be made in four narrow spectral bands, centered at 171 A (Fe 9), 195 A(Fe 12), 284 A (Fe 15), and 304 A (He 2) representing restricted temperature domains within a wide temperature range from 40,000 to 3,000,000 K. The results will be images of the solar atmosphere from the upper chromosphere and transition region to the active region corona. These maps, made at appropriate time intervals, will be used to study the fine structures in the solar corona and to relate their dynamic properties to the underlying chromosphere and photosphere. Dynamic events in the inner corona will be related to white light transients in the outer corona, and observations of the internal structure of coronal holes will be used to investigate origins of the solar wind. Title: Microlens arrays for Shack-Hartmann wavefront sensors Authors: Artzner, Guy Bibcode: 1992OptEn..31.1311A Altcode: Microlens arrays are a component of atmospheric wavefront sensors used recently with success by ground-based astronomers to obtain diffraction-limited images of stars in spite of wavefront disturbances introduced by the earth's atmosphere. Typical requirements for individual lenses are a size measured in tenths of millimeters, a sag measured in micrometers, and no room left between lenses, i.e., square or hexagonal lenses rather than circular lenses. Actual monolithic square microlens arrays up to 20 x 20 mm in size for 0.18- to 1.5-mm individual contiguous lenses of 0.0035-mm maximum sag are engraved in photoresist coatings by a two-axes rastering process. These arrays have been used for diurnal and nocturnal atmospheric wavefront measurements. Title: Rotational aperture synthesis: a proposal for ground-based observations. Authors: Artzner, Guy Bibcode: 1992ESASP.344..273A Altcode: 1992spai.rept..273A Attention is drawn to the existence of three-axes equatorial mounts for ground-based observing. The additional third axis with respect to a conventional two axes equatorial or alt-az mount allows to set the position angle at almost any predetermined value when observing close to the zenith. In addition to that the quasi-total absence of cantilever parts is an asset for interferometric stability. If the SIMURIS strategy uses some breadboard for fine structure imaging on the ground in the visible domain as an intermediate step between laboratory developments and flight operations the author investigates tactics for solar or stellar interferometric observations. Title: Solar Astrometry by Photolithography Authors: Artzner, G. Bibcode: 1990SoPh..128..281A Altcode: 1990IAUCo.121P.281A Observed temporal variations of shape and size of the solar disk as viewed from Earth may act as constraints for theories of the interior of the Sun. In addition to existing programs of solar diameter measurements we investigate a ground-based photographic method. Title: Massive composite bolometers for dark matter detection. Authors: Coron, N.; de Marcillac, P.; Artzner, G.; Leblanc, J.; Jegoudez, G.; Dambier, G.; Lepeltier, J. P.; Barthelemy, M.; Rothenflug, R.; Pari, P.; Tarrius, A.; Amoudry, F.; Stroke, H.; Testard, O. Bibcode: 1990qfcc.proc..275C Altcode: Massive composite bolometers cooled below 0.1K can detect recoil energy of particles with a very high efficiency. By using different absorber materials (Al2O3, Ge, Si, LiF, Cr2O3, TiO2...) some identification of dark matter particles will be possible. Resolutions in the 10 eV range for 1 kg of absorber material are theoretically possible at 0.01K if the thermistor is well matched to the substrate. The authors have successfully developed and tested a 25 g sapphire bolometer at 0.1K and have obtained for a 60 keV gamm-line a resolution of 16 keV FWHM, limited by extraneous noise. First bolometric spectra of radioactivity and cosmic ray backgrounds obtained at sea level are presented. Title: Extreme ultraviolet imaging telescope on board the Solar Heliospheric Observatory Authors: Delaboudiniere, Jean-Pierre; Gabriel, Alan H.; Artzner, Guy E.; Millier, F.; Michels, Donald J.; Dere, Kenneth P.; Howard, Russell A.; Kreplin, Robert W.; Catura, Richard C.; Stern, Robert A.; Lemen, James R.; Neupert, Werner M.; Gurman, Joseph B.; Cugnon, P.; Koeckelenbergh, A.; van Dessel, E. L.; Jamar, Claude A.; Maucherat, Andre J.; Chauvineau, Jean-Pierre; Marioge, Jean-Paul Bibcode: 1989SPIE.1160..518D Altcode: 1989xeoa.conf..518D The design of the multibandpass Extreme-Ultraviolet Imaging Telescope designed for 1996 launch on board the Solar Heliospheric Observatory is described. The telescope will observe simultaneously distinct temperature ranges in the solar corona, defined by well chosen emission lines. Images in four narrow bandpasses at wavelengths ranging from 17 to 31 nm will be obtained using normal-incidence multilayered optics deposited on quadrants of a Ritchey-Chretien telescope. Results are presented on the performances measured on a 2/3 scale mock-up. The bandpasses could be adjusted to better than 1 percent in wavelength. Title: Static wavefront correction by Linnik interferometry. Authors: Artzner, G. Bibcode: 1989SPIE.1013..233A Altcode: The author considers optical systems with residual peak to valley wavefront errors below 150 nm. The interference figure for λ = 633 nm may then be adjusted and photographed as to hold out at every point of the image of the pupil a one to one relationship between the optical density of the interferogram and the magnitude of the wavefront error. An enduring interference figure is secured by means of a tiny reflecting aluminized spot on a bare substrate located on the image of a distant point source. The author investigates how subsequent photoreproduction of an interferogram upon a photoresist coating may act as a transmitting or reflecting wavefront corrector. Title: EIT: Solar corona synoptic observations from SOHO with an Extreme-ultraviolet Imaging Telescope Authors: Delaboudiniere, J. P.; Gabriel, A. H.; Artzner, G. E.; Michels, D. J.; Dere, K. P.; Howard, R. A.; Catura, R.; Stern, R.; Lemen, J.; Neupert, W. Bibcode: 1988sohi.rept...43D Altcode: The Extreme-ultraviolet Imaging Telescope (EIT) of SOHO (solar and heliospheric observatory) will provide full disk images in emission lines formed at temperatures that map solar structures ranging from the chromospheric network to the hot magnetically confined plasma in the corona. Images in four narrow bandpasses will be obtained using normal incidence multilayered optics deposited on quadrants of a Ritchey-Chretien telescope. The EIT is capable of providing a uniform one arc second resolution over its entire 50 by 50 arc min field of view. Data from the EIT will be extremely valuable for identifying and interpreting the spatial and temperature fine structures of the solar atmosphere. Temporal analysis will provide information on the stability of these structures and identify dynamical processes. EIT images, issued daily, will provide the global corona context for aid in unifying the investigations and in forming the observing plans for SOHO coronal instruments. Title: Astronomical optics: Zonal aberration correction - Laboratory experiments and extrapolations to space- and ground-based observations Authors: Artzner, G. Bibcode: 1987A&A...175..345A Altcode: The author describes the results of a laboratory experiment with a 143 mm diameter Cassegrainian telescope plagued by static irregular zonal aberrations with rotational symmetry and 620 nm peak to valley amplitude wavefront error. An adapted 16 mm useful diameter intrafocal corrector plate has been surfaced using a 2 μ-thickness photoresist coating on an optical substrate, ad-hoc non-uniform exposure via a two-axis computercontrolled scanning device and subsequent development and baking. The effect of losses by diffusion and absorption due to the corrector plate is small with respect to the increase of contrast due to the wavefront correction. Three extrapolations of this experiment are discussed: (1) How to use correctors in the UV range where the size of the Airy disk becomes smaller for a given aperture. (2) Correction of aberrations with no rotational symmetry. (3) Feasible correctors and relay optics adapted to large (4-8 m diameter) instruments have a 50 mm corrected field, well matched to modern image detectors. Title: Aspherical surfaces engraved on photoresist coatings: manufacture of a zonal corrector plate for an aberrating Cassegrainian telescope. Authors: Artzner, G. Bibcode: 1987SPIE..805..162A Altcode: We investigate how aspherical optical surfaces engraved in photoresist coatings avail against static wavefront aberrations up to 3 μ. The spherical aberration of a singlet lens is corrected for. The image given by a cassegrainian telescope of 143 mm diameter with a peak to valley 0,62 µ wavefront error and 7" slopes is improved by a 16 mm diameter intrafocal phase equalizer corrector plate. We then discuss extrapolations of our laboratory experiments. Title: Bolometers as particle spectrometers Authors: Stroke, H. H.; Artzner, G.; Coron, N.; Dambier, G.; Hansen, P. G. Bibcode: 1986ITNS...33..759S Altcode: A spectrometer based on low-temperature calorimetry has been under development since 1983. The present detector, capable of recording individual alpha and beta particles and X-ray photons, is based on a composite diamond-germanium bolometer. The advantage of a composite bolometer is that it separates the absorption and detection functions. Diamond, as an absorber, is of particular advantage because of its low heat capacity and high thermal diffusivity. The goal is a theoretical energy resolution of a few eV at 0.1 K. Initial experiments at 1.3 K and 0.9 K, which give resolutions in the keV range, are still noise-limited. High-resolution applications, such as in X-ray astronomy and nuclear physics (in particular, neutron mass measurements) are foreseen. Title: Composite bolometers as spectrometers for X-ray astronomy Authors: Coron, N.; Artzner, G.; Dambier, G.; Jegoudez, G.; Leblanc, J. Bibcode: 1986SPIE..597..389C Altcode: The detection of single events like the absorption of gamma or X-rays and alpha or beta particles with cooled thermal detectors is now well established and first resolutions obtained are promising. The paper investigates the possibilities of the composite bolometer which offers the advantage of separating the absorption, thermal diffusion and thermometric functions. An optimal configuration is the diamond composite bolometer with a monolithic thermistor. Experimental results are presented on the simultaneous detection of different kinds of events at 1 K temperature. These results confirm the high linearity of this detector and its ability to accept rather high counting rates. As a conclusion, an example of application to X-ray astronomy is presented and some problems or developments to be studied for a space mission are underlined. Title: Bolometers as spectrometers for X-ray astronomy. Authors: Coron, N.; Artzner, G.; Dambier, G.; Jegoudez, G.; Leblanc, J.; Deschamps, J. Y.; Rocchia, R.; Tarrius, A.; Testard, O.; Ravn, H. R.; Stroke, H. H.; Jonson, B. Bibcode: 1985ESASP.239..229C Altcode: 1985cxrs.work..229C The authors have investigated the possibility to use composite diamond-germanium bolometers, originally developed for I.R. astronomy, for the individual detection of X-ray photons. Title: On the possible use of deep U.V. photoresists correctors to obtain the ultimate U.V. resolution of space borne telescopes. Authors: Dame, L.; Bonnet, R. M.; Artzner, G. E. Bibcode: 1984SPIE..445..318D Altcode: Large space-borne telescopes are limited in their ultraviolet resolution by their large and medium scale (20 - 30 cm) surface irregularities (ripples). The authors present the principle, instrumentation and first results of a new interferometric method using a Michelson-Twyman configuration (diverging light beams) that allows to engrave on deep U.V. photoresists a phase compensating plate which permit to revocer, partly or entirely, the diffraction limited resolution of the telescope. The corrector that they obtain is a phase compensating plate in reflection with highs and lows on its surface perfectly conjugated in negative, with the primary mirror surface irregularities. Title: Solar H-Lyman-α Flux and Profile Relative Measurements from OSO-8: January 1976 to March 1978 Authors: Artzner, G. Bibcode: 1983wcrs.proc...87A Altcode: More than 1,900 monochromatic full solar disk raster images of the H Lyman-alpha 121.6-nm line have been calibrated by reference to nearly simultaneous profiles of the Lyman-alpha line emitted by small, quiet areas of the solar disk. The observations and the calibration procedures are described. Values of the full line flux vary in a relative range 1 to 1.5 between January 1976 and March 1978. A hypothetical 35 to 60 percent variation of the solar flux between July 1976 and October 1977, as published with Atmosphere Explorer E results, is likely to be closer to 30 to 35 percent. Any variation of the shape of the full disk Lyman-alpha line profile is undetectable between December 9, 1976 and May 10, 1978. Title: Structure and Physics of Solar Faculae - Part Two - the Non-Thermal Velocity Field above Faculae Authors: Mouradian, Z.; Dumont, S.; Pecker, J. -C.; Chipman, E.; Artzner, G. E.; Vial, J. C. Bibcode: 1982SoPh...78...83M Altcode: The OSO-8 satellite enabled us to study various characteristics of the profiles of Si II, Si IV, C IV, and O VI lines above active areas of the Sun, as well as above quiet areas, and to derive some physical properties of the transition region between chromosphere and corona (CCT): (i) The study of the lines shows a general tendency for the microvelocity fields on the average to be nearly constant for the heights corresponding to T > 105 K; however they seem to slightly increase with height in quiet areas, and decrease in active areas. (ii) A multicomponent model of the CCT is however quite necessary, and its geometry is far from being a set of plane-parallel columns. It is similar to an association of moving knots within the non-moving principal component of the matter. (iii) The proportion of mass, in the knots relative to that in the non-moving component, is several times larger in active regions than in quiet regions. (iv) In the knots, the non-thermal microvelocity fields are smaller in active regions and seem to decrease for T increasing above 105 K, contrary to what happens in the steady principal component. Of course, we consider that microturbulence and Doppler shift are two aspects of the same distribution of velocity. Title: Physical properties of the solar chromosphere deduced from optically thick lines. I - Observations, data reduction, and modelling of an average plage Authors: Lemaire, P.; Gouttebroze, P.; Vial, J. C.; Artzner, G. E. Bibcode: 1981A&A...103..160L Altcode: Simultaneous Ca II H and K, Mg II h and k, and H I Lyman-alpha and Lyman-beta profiles have been recorded by the OSO-8/LPSP spectrometer on a quiet sun area and a part of plage, McMath 13738. After data reduction and filtering, a full set of calibrated profiles is obtained. Using a code developed at LPSP (Gouttebroze et al., 1978), profiles computed from VAL III model C (Vernazza et al., 1981) are compared to observations. A specific plage model has been computed to fit the observed profiles. This model reproduces successfully Ca II H and K, and H I Lyman-alpha and Lyman-beta, but partly fails with Mg II h and k. Atmospheric inhomogeneities and dynamical effects may contribute to this discrepancy, and it is proposed that the level number entering in the Mg II computation be increased to take account of a likely fluorescence induced by the H I Lyman-beta radiation field. Title: Absorption feature observed on the H Lyman-alpha solar line - an interpretation Authors: Artzner, G.; Cazes, S.; Emerich, C.; Vial, J. C.; Lemaire, P. Bibcode: 1981A&A...100..205A Altcode: A narrow absorption feature on the red part of the solar H Lyman-alpha profile has been observed by two instruments in 1975 and attributed to atomic hydrogen of the nearby interplanetary gas. This hypothesis implies that the absorption feature shifts with the position of the earth on its orbit. New measurements above active regions at other seasons rule out this hypothesis. On the other hand, appropriate laboratory calibrations indicate that the absorption feature is likely due to a ghost image of the geocoronal absorption. Title: OSO-8 Observations of CAII H and K MGII H and K Lyman-Alpha and Lyman-Beta above a Sunspot Authors: Kneer, F.; Scharmer, G.; Mattig, W.; Wyller, A.; Artzner, G.; Lemaire, P.; Vial, J. C. Bibcode: 1981SoPh...69..289K Altcode: Observations with the French (L.P.S.P.) experiment on board OSO-8 of a sunspot and nearby plage region are described. The behaviour of the emission cores of the Ca II H and K and Mg II h and k resonance lines is very similar and the correspondence in intensity between the four lines persists in all observed features. In contrast, the Lyman lines show little correlation with the other lines. Their emission regions appear broader in the spectroheliograms than the underlying sunspot structure and must not necessarily possess a counterpart in lower layers. From the central intensity of Lα above the umbra an electron density of 4.3 × 1010 cm-3 ≲ne* ≲2.3 × 1011 cm-3 at 20 000 K is estimated. Title: Solar H I LY alpha far wing measurement Authors: Jouchoux, A.; Vial, J. C.; Artzner, G. E.; Gouttebroze, P.; Lemaire, P. Bibcode: 1981A&A....93..415J Altcode: High spectral resolution photoelectric observations of the solar H I Ly alpha far wing are presented. Measurements above active regions and quiet sun center are compared to photographic observations of Basri et al. (1979). Title: On VI (λ = 1032 Å) profiles in and above an active region prominence, compared to quiet Sun center and limb profiles Authors: Vial, J. C.; Lemaire, P.; Artzner, G.; Gouttebroze, P. Bibcode: 1980SoPh...68..187V Altcode: O VI (λ = 1032 Å) profiles have been measured in and above a filament at the limb, previously analyzed in H I, Mg II, Ca II resonance lines (Vial et al., 1979). They are compared to profiles measured at the quiet Sun center and at the quiet Sun limb. Title: Microturbulence near the edge of a solar plage Authors: Simon, G.; Mouradian, Z.; Dumont, S.; Pecker, J. C.; Artzner, G.; Vial, J. C. Bibcode: 1980A&A....89L...8S Altcode: Observations of the Ca II K line at the edge of a solar plage show enhanced separation of the K2 peaks with respect to the measured value inside the plage and in the quiet sun. This effect may be interpreted as a variation of microturbulent motions at the height of formation of K2. Title: Observations of Chromospheric Lines from OSO-8 Authors: Grossmann-Doerth, U.; Kneer, F.; Uexkuell, M.; Artzner, G. E.; Vial, J. C. Bibcode: 1980SoPh...66....3G Altcode: The line profiles of Lα, Ca II K and Mg IIk were measured with the spectrometer of the `Laboratoire de Physique Stellaire et Planétaire' on board of OSO-8. The results of these measurements are presented. Title: Center-to-limb solar observations of the K2 component of the Ca II K line with the OSO 8 satellite. Authors: Dumont, S.; Mouradian, Z.; Pecker, J. -C.; Simon, G.; Artzner, G. E.; Vial, J. C. Bibcode: 1980CRASB.290..365D Altcode: OSO 8 spectrometer measurements of the separation between emission peaks in the K2 Ca II line across the solar disk in quiet and active regions are presented. The center-to-limb variation in emission peak separation is found to differ slightly for quiet and facula regions at distances greater than 0.2 solar radii from the limb, in agreement with previous observations. For a facula located at the solar limb, however, the peak separation is observed to be up to 35 percent greater than in quiet regions, indicating the presence of a region of enhanced chromospheric turbulence surrounding the faculae. Title: Non thermal velocities in the chromosphere-corona transition zone of solar active regions. Authors: Dumont, S.; Mouradian, Z.; Pecker, J. -C.; Chipman, E.; Artzner, G.; Vial, J. -C. Bibcode: 1980CRASB.290..317D Altcode: OSO 8 satellite observations of lines of the Si II, Si IV, C IV and O VI ions in the ultraviolet spectrum of active solar regions are considered. It is noted that for the case of pronounced physical dispersion of the data, there is no marked systematic variation from the center to the edge of the solar disk. The nonthermal velocities in the transition zone are, for a given temperature, the same as for quiet regions. In addition, the velocities tend to reach a constant value at temperatures above 100,000 deg K, and the observed physical dispersion is much higher than the inaccuracy of the data. Title: Profiles of H I (Lalpha ), Mg II (h and k), Ca II (H and K) lines of an active filament at the limb, with the LPSP instrument aboard the OSO-8 satellite. Authors: Vial, J. C.; Gouttebroze, P.; Artzner, G.; Lemaire, P. Bibcode: 1979SoPh...61...39V Altcode: We scanned the H I Lα, Mg II h and k, Ca II K and H lines simultaneously with the LPSP instrument on OSO-8, to investigate the low and moderate temperature regions of an `active region filament'. The Lα line is not reversed except for the innermost position in the prominence. Intensity (k/h), (K/H) ratios are respectively 2 and 1.1, indicating that the Mg II lines are optically thin, and that Ca II K is saturated, although not clearly reversed. The results obtained during the second sequence of observations (K saturated before Lα for example) indicate that within the size of the slit (1″ × 10″) we are not observing the same emitting features in the different lines. Title: Profiles of H i (Lyα), MG II (h and K), CA II (h and k) Lines in an Active Filament at the Limb, Observed with the LPSP Instrument Onboard the OSO-8 Satellite. Authors: Vial, J. C.; Gouttebroze, P.; Artzner, G.; Lemaire, P. Bibcode: 1979phsp.coll..250V Altcode: 1979IAUCo..44..250V No abstract at ADS Title: The Solar H-Lyman-alpha Line Authors: Artzner, G. Bibcode: 1978A&A....70L..11A Altcode: Summary A precise measurement of the solar H-Lya 121.6 nm profile is presented. A preliminary analysis indicates a) a 2.4 1 0.6 km/s redshift of the solar H-Lya emission over a moderately active region with respect to the geocoronal absorption ; and b) the presence of a faint absorption feature, redshif ted 32 km/s with respect to the geocoronal absorption line. Key words : Lyman-alpha - Solar spectrum - Chromosphere Downf low - Interstellar hydrogen. Title: The solar hydrogen Lyman-beta and Lyman-alpha lines: disk center observations from OSO 8 compared with theoretical profiles. Authors: Gouttebroze, P.; Lemaire, P.; Vial, J. C.; Artzner, G. Bibcode: 1978ApJ...225..655G Altcode: The solar La and Lfl lines of hydrogen have been measured at the center of the disk with the LPSP spectrometer aboard OSO 8. These line profiles are compared with theoretical profiles obtained with different solar atmospheric models, assuming either complete or partial frequency redistribution in scattering. The assumption of microturbulence for the velocity fields appears insufficient to account for the profiles of the line cores; better results are obtained with a blend of micro- and macroturbulence, which shows the need of a generalized treatment of the turbulent motions in the formation of these lines. If the effects of partial redistribution are taken into account, a good fit of the line wings requires higher temperatures, in the region under the plateau, than in the reference atmospheric model of Vernazza, Avrett, and Loeser. Subject headings: line formation - line profiles - Sun: chromosphere - Sun: spectra - ultraviolet: spectra Title: Simultaneous time-resolved observations of the H Lalpha , Mg k 2795 Å, and Ca K solar lines. Authors: Artzner, G.; Leibacher, J.; Vial, J. C.; Lemaire, P.; Gouttebroze, P. Bibcode: 1978ApJ...224L..83A Altcode: No abstract at ADS Title: Calibrated full disk solar H I Lyman-alpha and Lyman-beta profiles. Authors: Lemaire, P.; Charra, J.; Jouchoux, A.; Vidal-Madjar, A.; Artzner, G. E.; Vial, J. C.; Bonnet, R. M.; Skumanich, A. Bibcode: 1978ApJ...223L..55L Altcode: Resolved solar H I Ly-alpha and -beta profiles have been recorded by the French LPSP experiment on OSO 8. Intensity observations at the center and the limb have been combined to obtain flux-equivalent profiles (5.46 plus or minus 30 percent and 0.078 plus or minus 25 percent erg/sq cm per sec for Ly-alpha and -beta, respectively). Comparison of the flux profiles with unresolved calibration rocket profiles allows one to obtain an absolute calibration. Title: The LPSP instrument on OSO 8. II. In-flight performance and preliminary results. Authors: Bonnet, R. M.; Lemaire, P.; Vial, J. C.; Artzner, G.; Gouttebroze, P.; Jouchoux, A.; Leibacher, J. W.; Skumanich, A.; Vidal-Madjar, A. Bibcode: 1978ApJ...221.1032B Altcode: The paper describes the in-flight performance for the first 18 months of operation of the LPSP (Laboratoire de Physique Stellaire et Planetaire) instrument incorporated in the OSO 8 launched June 1975. By means of the instrument, an absolute pointing accuracy of nearly one second was achieved in orbit during real-time operations. The instrument uses a Cassegrain telescope and a spectrometer simultaneously observing six wavelengths. In-flight performance is discussed with attention to angular resolution, spectral resolution, dispersion and grating mechanism (spectral scanner) stability, scattered light background and dark current, photometric standardization, and absolute calibration. Real-time operation and problems are considered with reference to pointing system problems, target acquisition, and L-alpha modulation. Preliminary results involving the observational program, quiet sun and chromospheric studies, quiet chromospheric oscillation and transients, sunspots and active regions, prominences, and aeronomy investigations are reported. Title: Doppler Shifts measured in 0 VI line from OSO-B observations above and in the vicinity of plage Mc Math 13738. Authors: Lemaire, P.; Skumanich, A.; Artzner, G.; Gouttebroze, P.; Vial, J. C.; Bonnet, R. M.; McWhirter, P. Bibcode: 1978BAAS...10Q.440L Altcode: No abstract at ADS Title: OSO-8 Radio and X-ray observations of the 19 April 1977 flare. Authors: Skumanich, A.; Jouchoux, A.; Castelli, J.; Lemaire, P.; Artzner, G.; Gouttebroze, P.; Vial, J. C.; Bonnet, R. M. Bibcode: 1978BAAS...10..441S Altcode: No abstract at ADS Title: EUV observations of class-C X-ray flare by the LPSP (Laboratoire de Physique Stellaire et Planétaire du Centre National de la Recherche Scientifique) spectrometer on OSO-8. Authors: Jouchoux, A.; Skumanich, A.; Bonnet, R. M.; Lemaire, P.; Artzner, G.; Leibacher, J.; Vial, J. C.; Vidal-Madjar, A. Bibcode: 1977BAAS....9..432J Altcode: No abstract at ADS Title: The LPSP experiment on OSO-8. I - Instrumentation, description of operations, laboratory calibrations and pre-launch performances Authors: Artzner, G.; Bonnet, R. M.; Vial, J. C.; Jouchoux, A.; Leibacher, J.; Vidal-Madjar, A.; Lemaire, P. Bibcode: 1977SSI.....3..131A Altcode: The characteristics of OSO-8, including its solar-pointed instrument assembly and rasters, are discussed, as well as the accompanying Laboratoire de Physique Stellaire et Planetaire (LPSP) instrumentation, which is designed to study the solar atmosphere with high spatial, spectral, and temporal resolution. The LPSP instrument, which consists of two subassemblies, a Cassegrainian telescope and a spectrometer, is described; main optical characteristics, including spectral lines observed, and means of correcting aberrations and eliminating stray light, are given for the spectrometer. Detectors and their capacities, and various filter wheel configurations available for detection of polarized light and discrimination of low orders of diffraction, are also described. The observation program, which consists of a study of solar prominences, flares, and dynamic and three-dimensional physical structures of the chromosphere, as well as determination of seasonal variations of some gases in earth's atmosphere, is reviewed. A detailed account of pre-launch tests and calibration procedures is also given. Title: Extreme-Ultraviolet Observations of New Cycle Sunspots with the LPSP Spectrometer from OSO-8 Authors: Skumanich, A.; Jouchoux, A.; Artzner, G.; Bonnet, R. M.; Leibacher, J.; Lemaire, P.; Vial, J. C.; Vidal-Madjar, A. Bibcode: 1977BAAS....9..340S Altcode: No abstract at ADS Title: On VI Profiles of Solar Quiet and Active Areas Recorded by OSO-8 LPSP Experiment". Authors: Lemaire, P.; Artzner, G.; Vial, J. C.; Bonnet, R. M.; Gottebroze, P.; Jouchoux, A.; Vidal-Madjar, A.; McWhirter, P.; Leibacher, J.; Skumainich, A. Bibcode: 1977uxsa.coll...46L Altcode: 1977IAUCo..43...46L No abstract at ADS Title: OSO-8 Observations of the EUV Chromospheric Network Authors: Artzner, G.; Bonnet, R. M.; Leibacher, J.; Lemaire, P.; Skumanich, A.; Vial, J. C.; Vidal-Madjar, A. Bibcode: 1976BAAS....8..332A Altcode: No abstract at ADS Title: Solar OVI Profiles as Observed by the French Experiment Aboard OSO-8 Authors: Lemaire, P.; Artzner, G.; Bonnet, R. M.; Vial, F. C.; Skumanich, A.; Leibacher, J.; Vidal-Madjar, A. Bibcode: 1976BAAS....8R.331L Altcode: No abstract at ADS Title: Evolution of sunspot and active region morphology as observed on the resonance lines of Ca+ (K, H), Mg+ (k, h), hydrogen (Lalpha , Lbeta ), and O VI from OSO-8 (LPSP). Authors: Artzner, G.; Skumanich, A.; Bonnet, R. M.; Vidal-Madjar, A.; Leibacher, J.; Lemaire, P.; Vial, J. C. Bibcode: 1976BAAS....8..397A Altcode: No abstract at ADS Title: Periodic temporal phenomena in the solar chromosphere as observed from OSO-8 (LPSP). Authors: Vial, J. C.; Leibacher, J.; Lemaire, P.; Artzner, G.; Bonnet, R. M.; Skumanich, A.; Vidal-Madjar, A. Bibcode: 1976BAAS....8..397V Altcode: No abstract at ADS Title: Spatial variations of solar profiles of Ca+ H and K, Mg+ h and k, and Lyman alpha and beta (H I) resonance lines as observed from OSO-8 (LPSP). Authors: Bonnet, R. M.; Artzner, G.; Leibacher, J.; Lemaire, P.; Skumanich, A.; Vial, J. C.; Vidal-Madjar, A. Bibcode: 1976BAAS....8..397B Altcode: No abstract at ADS Title: Prominence Observations with the OSO-8 French Experiment Authors: Vial, J. C.; Artzner, G.; Bonnet, R. M.; Lemaire, P.; Leibacher, J.; Skumanich, A.; Vidalmadjar, A. Bibcode: 1976BAAS....8..344V Altcode: No abstract at ADS Title: High-Resolution Atmospheric Extinction Measurements from the French Experiment on Board the NASA Spacecraft OSO-8 Authors: Vidal-Madjar, A.; Roble, R. G.; Mankin, W. G.; Artzner, G.; Bonnet, R. M.; Lemaire, P.; Vial, J. C. Bibcode: 1976ASSL...61..117V Altcode: 1976aps..conf..117V No abstract at ADS Title: High resolution atmospheric extinction measurements from the French experiment on board the NASA spacecraft OSO-8 Authors: Vidal-Madjar, A.; Artzner, G.; Bonnet, R. M.; Lemaire, P.; Vial, J. C.; Roble, R. G.; Mankin, W. G. Bibcode: 1976atps.proc..117V Altcode: The French instrument aboard OSO-8 is a multichannel, high-resolution UV spectrometer for observing very small areas of the sun simultaneously in the Ca II, Mg II, Lyman alpha, and Lyman beta lines. By observing extinction through the earth atmosphere, the spectrometer studies the three-dimensional structure and the composition of the atmosphere. The quality of data appears to give a 500 m vertical resolution both for O3 and O2; O3 is observed primarily from 55 to 75 km, while O2 is observed from 85 to 200 km. Data on the hydrogen absorption present a new method for evaluating exospheric temperature and atomic hydrogen density at each point of the exobase. Title: High Resolution Spectroscopy of the Disk Chromosphere. III: Upward Moving Disturbances as Observed in the Ca II K-Line Wings Authors: Beckers, J. M.; Artzner, G. Bibcode: 1974SoPh...37..309B Altcode: We describe the properties of dark structures which are seen in the K-line wings and which seem to propagate inward into the K-line core, or upward in the solar atmosphere. These so-called dark whiskers appear to be related to the bright disturbances (bright whiskers) described by Liu (1974). Both may be related to the shocks that heat the chromosphere and corona.