Author name code: roddier ADS astronomy entries on 2022-09-14 author:"Roddier, Francois" ------------------------------------------------------------------------ Title: Adaptive Optics in Astronomy Authors: Roddier, François Bibcode: 2004aoa..book.....R Altcode: Part I. Introductory Background: 1. Historical context F. Roddier; 2. Imaging through the atmosphere F. Roddier; Part II. The Design of an Adaptive Optics System: 3. Theoretical aspects F. Roddier; 4. Wave-front compensation devices M. Séchaud; 5. Wave-front sensors G. Rousset; 6. Control techniques P.-Y. Madec; 7. Performance estimation and system modeling M. Northcott; Part III. Adaptive Optics with Natural Guide Stars: 8. The COME-ON/ADONIS systems G. Rousset and J.-L. Beuzit; 9. The UH-CFHT systems F. Roddier and F. Rigaut; 10. Adaptive optics in solar astronomy J. Beckers; Part IV. Adaptive Optics with Laser Beacons: 11. Overview of adaptive optics with laser beacons D. Sandler; 12. The design of laser beacon AO systems D. Sandler; 13. Laser beacon adaptive optics systems D. Sandler; Part V. The Impact of Adaptive Optics in Astronomy: 14. Observing with adaptive optics P. Léna and O. Lai; 15. Astronomical results P. Léna and O. Lai; 16. Future expectations F. Roddier; Index. Title: New neighbours. III. 21 new companions to nearby dwarfs, discovered with adaptive optics Authors: Beuzit, J. -L.; Ségransan, D.; Forveille, T.; Udry, S.; Delfosse, X.; Mayor, M.; Perrier, C.; Hainaut, M. -C.; Roddier, C.; Roddier, F.; Martín, E. L. Bibcode: 2004A&A...425..997B Altcode: 2001astro.ph..6277B We present some results of a CFHT adaptive optics search for companions to nearby dwarfs. We identify 21 new components in solar neighbourhood systems, of which 13 were found while surveying a volume-limited sample of M dwarfs within 12 pc. We are obtaining complete observations for this subsample, to derive unbiased multiplicity statistics for the very-low-mass disk population. Additionally, we resolve for the first time 6 known spectroscopic or astrometric binaries, for a total of 27 newly resolved companions. A significant fraction of the new binaries has favourable parameters for accurate mass determinations. The newly resolved companion of Gl 120.1C was thought to have a spectroscopic minimum mass in the brown-dwarf range (Duquennoy & Mayor \cite{duquennoy91}), and it contributed to the statistical evidence that a few percent of solar-type stars might have close-in brown-dwarf companions. We find that Gl 120.1C actually is an unrecognised double-lined spectroscopic pair. Its radial-velocity amplitude had therefore been strongly underestimated by Duquennoy & Mayor (\cite{duquennoy91}), and it does not truly belong to their sample of single-lined systems with minimum spectroscopic mass below the substellar limit. We also present the first direct detection of Gl 494B, an astrometric brown-dwarf candidate. Its luminosity straddles the substellar limit, and it is a brown dwarf if its age is less than ∼300 Myr. A few more years of observations will ascertain its mass and status from first principles.

Based on observations made at Canada-France-Hawaii Telescope, operated by the National Research Council of Canada, the Centre National de la Recherche Scientifique de France and the University of Hawaii. Some of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. Title: Deconvolution of astronomical images obtained from ground-based telescopes with adaptive optics Authors: Fusco, Thierry; Mugnier, Laurent M.; Conan, Jean-Marc; Marchis, Franck; Chauvin, G.; Rousset, Gerard; Lagrange, Anne-Marie; Mouillet, David; Roddier, Francois J. Bibcode: 2003SPIE.4839.1065F Altcode: Deconvolution is a necessary tool for the exploitation of adaptive optics corrected images, because the correction is partial. The Maximum A Posteriori (MAP) framework is used to derive a deconvolution method (MISTRAL) that combines the data with our knowledge of the noise statistics as well as our prior information about the object and the variability of the Point Spread Function. The deconvolution of experimental and scientific data illustrates the capabilities of this method. Title: A nulling wide field imager for exoplanets detection and general astrophysics Authors: Guyon, O.; Roddier, F. Bibcode: 2002A&A...391..379G Altcode: 2002astro.ph..5523G We present a solution to obtain a high-resolution image of a wide field with the central source removed by destructive interference. The wide-field image is created by aperture synthesis with a rotating sparse array of telescopes in space. Nulling of the central source is achieved using a phase-mask coronagraph. The full (u,v) plane coverage delivered by the 60 m, six 3-meter telescope array is particularly well-suited for the detection and characterization of exoplanets in the infrared (DARWIN and Terrestrial Planet Finder (TPF) missions) as well as for other generic science observations. Detection (S/N=10) of an Earth-like planet is achieved in 10 hours with a 1 mu m bandwidth at 10 mu m. Title: Curvature Wavefront Sensor For Solar Adaptive Optics Authors: Molodij, G.; Roddier, F.; Kupke, R.; Mickey, D. L. Bibcode: 2002SoPh..206..189M Altcode: Active or adaptive optics often require the ability to characterize wavefront aberrations using natural extended sources. The task becomes especially challenging when dealing with widely extended sources such as the solar granulation. We propose a new approach based on the processing of oppositely defocused images. This method, which is a generalization of a technique known as curvature sensing, derives the wavefront curvature from the difference between two oppositely defocused images and determines the second momenta of the point spread function. The proposed method measures the wavefront aberration from the images themselves, requires little computational resources, is fast enough to be used in a real-time adaptive optics system and is particularly adapted to random patterns such as solar granulation or spot penumbras whose morphology evolves during the observation. We envision the application of the method to real-time seeing compensation in solar astronomical telescopes, and to the correction of optical system aberrations in remote sensing instrumentation. This effort is directed towards building a curvature sensor for the real-time applications. Title: Atmospheric limitations to adaptive image compensation (Invited Speaker) Authors: Roddier, F. Bibcode: 2002ASPC..266..546R Altcode: 2002asev.conf..546R No abstract at ADS Title: Concepts for a Large-Aperture, High Dynamic Range Telescope Authors: Kuhn, J. R.; Moretto, G.; Racine, R.; Roddier, F.; Coulter, R. Bibcode: 2001PASP..113.1486K Altcode: This paper summarizes concept studies for a large telescope capable of wide-field imaging and of the highest possible dynamic range for photometry and angular resolution. Point-spread functions (PSFs) and scattered light levels at large offsets are computed and compared for four telescopes of the same light-gathering power but with different pupil functions:1. a reference monolithic mirror telescope with a 17.4 m primary,2. a segmented mirror telescope (SMT) with a hexagonally segmented primary,3. a hexagonal off-axis telescope (HOT) with a distributed aperture made of 6×6.5 m unobstructed circular mirrors that are identical off-axis sections of a parent 20 m mirror, and4. a square off-axis telescope (SOT) whose aperture is made of 4×8 m off-axis mirrors. The characteristics of the PSFs are examined in the diffraction- and seeing-limited regimes, assuming (1) perfect mirror figure and (2) realistic figure errors (edge defects). The implications of field rotation with an altitude-azimuth mounting are discussed in each case. The implementation of adaptive optics (AO) and the properties of AO-compensated PSFs having a Strehl ratio of 0.5, and of coronagraphic imaging, are also discussed for the four configurations. It is shown that, in the seeing-limited regime and as intuitively expected, the optical performance of all four telescopes is comparable. With higher order adaptive optics and for coronagraphic observations, the SOT and HOT are superior to the SMT. This distinction becomes larger with relaxed constraints on mirror edge-polishing requirements. A full optical design is presented for the novel HOT configuration, and optical fabrication issues are briefly addressed. Finally, science programs and possible instrumentation layouts with the HOT are briefly explored for different modes of operation. It appears that the natural ``optical bench'' configuration of the HOT can provide a remarkably versatile and convenient environment for instrument deployment. Title: Detection of arcs in Saturn's F ring during the 1995 Sun ring-plane crossing Authors: Charnoz, S.; Brahic, A.; Ferrari, C.; Grenier, I.; Roddier, F.; Thébault, P. Bibcode: 2001A&A...365..214C Altcode: 2000astro.ph.10449C Observations of the November 1995 Sun crossing of the Saturn's ring-plane made with the 3.6 m CFH telescope, using the UHAO adaptive optics system, are presented here. We report the detection of four arcs located in the vicinity of the F ring. They can be seen one day later in HST images. The combination of both data sets gives accurate determinations of their orbits. Semi-major axes range from 140 020 km to 140 080 km, with a mean of 140 060 +/- 60 km. This is about 150 km smaller than previous estimates of the F ring radius from Voyager 1 and 2 data, but close to the orbit of another arc observed at the same epoch in HST images. Title: Aperture Rotation Synthesis: Optimization of the(u, v)-Plane Coverage for a Rotating Phased Array of Telescopes Authors: Guyon, Olivier; Roddier, François Bibcode: 2001PASP..113...98G Altcode: The problem of optimizing the (u, v)-plane coverage of a rotating phased array of telescopes is assessed. We search for solutions for maximum uniform (u, v)-plane coverage. Using a simulated annealing algorithm, we find the optimal configurations for rotating arrays with between four and 10 identical telescopes. With few modifications, the same algorithm can find optimal array configurations adapted to specific observations for which the optimal (u, v)-plane coverage is different. We also demonstrate that such rotation-optimized arrays are capable of recovering images of complex sources and obtaining spectroscopic information. Title: Substellar mass companion search with adaptive optics at University of Hawaii Authors: Baudoz, P.; Roddier, F.; Roddier, C.; Guyon, O.; Potter, D.; Brandner, W.; Gay, J.; Rabbia, Y.; Close, L. Bibcode: 2000AAS...197.5208B Altcode: 2000BAAS...32.1491B We present the search of substellar mass companions around nearby stars which we are pursuing at University of Hawaii. Our strategy for such survey embraces the use of two different instruments: The University of Hawaii adaptive optics curvature system Hokupa'a placed on Gemini North and the Observatoire de la Cote d'Azur Nulling Coronagraph (called AIC) which is installed on PUEO (CFHT adaptive optics). We will show how the two instruments are complementary for a substellar mass survey. Preliminary results will be shown to demonstrate that the point source detection limit with Hokupa'a on Gemini is very efficient at angular distances larger than one arcseconds (8 magnitudes in K at one arcsecond) while the point source detection limit for AIC on PUEO/CFHT is more efficient at shorter angular distances (4 magnitudes in K at 0.1 arcsecond). This research acknowledges support by NSF, NASA and CNRS. Title: QSO hosts imaging capabilities of Hokupa'a on the Gemini North telescope Authors: Guyon, O.; Sanders, D.; Roddier, C.; Roddier, F.; Brandner, W.; Baudoz, P.; Potter, D. Bibcode: 2000AAS...197.5209G Altcode: 2000BAAS...32R1491G The University of Hawaii Adaptive Optics system, Hokupa'a, now operating on the Gemini North telescope, offers unique possibilities of high resolution and high dynamical range imaging of quasar hosts. This is the only Adaptative Optics system able to guide on faint targets (up to V magn = 17 to 18) on a 8-m class telescope, delivering images with FWHM from 0.1 to 0.2 arcsec in K and H bands for magnitude 16 sources. With careful PSF substraction, we find that we can detect point sources with a 7 magnitudes difference at 0.6 arcsec and 6 magnitudes difference at 0.25 arcsec. We are currently carrying out a deep, high dynamical range, volume-limited imaging survey of QSO hosts. We give hosts magnitude detection limits for various QSO V magnitudes and show how this work can answer some questions about the formation of quasars. Title: Instrumentation: Adaptive Optics Authors: Roddier, F. Bibcode: 2000eaa..bookE2913R Altcode: Turbulence in the Earth's atmosphere produces inhomogeneities in the refractive index of the air, which affect the image quality of ground-based telescopes (see SEEING). ADAPTIVE OPTICS (AO) is a means for the real-time compensation of image degradation. It consists of using an active optical element such as a deformable mirror to correct the instantaneous wave-front distortions. These are measur... Title: Erratum: Neptune's Cloud Structure and Activity: Ground-based Monitoring with Adaptive Optics, Volume 136, Number 1, pp.168-172 (1998) Authors: Roddier, F.; Roddier, C.; Graves, J. E.; Northcott, M. J.; Owen, T. Bibcode: 2000Icar..148..320R Altcode: No abstract at ADS Title: A High-Resolution Polarimetry Map of the Circumbinary Disk around UY Aurigae Authors: Potter, Daniel E.; Close, Laird M.; Roddier, François; Roddier, Claude; Graves, J. E.; Northcott, Malcolm Bibcode: 2000ApJ...540..422P Altcode: We have obtained J-band (1.2 μm) polarimetry observations of the circumbinary disk around UY Aurigae. These observations were made possible by the use of the University of Hawaii 36 element adaptive optics instrument, Hokupa'a, at the 3.35 m CFHT. The deep (120 minute), high-resolution (0.15") polarization images reveal a centrosymmetric polarization signature from the light scattered off the circumbinary dust disk which is ~106 times fainter than the stars in the binary system. A comparison with a Mie scattering model of the circumbinary disk in UY Aurigae suggests that the polarization signature is dominated by the smallest grains in the disk (~0.03 μm) and further supports the hypothesis that the resolved light seen in the optical and infrared originates from a large flattened disk of dust surrounding both stars. Title: Direct exoplanet imaging possibilities of the nulling stellar coronagraph Authors: Guyon, Olivier; Roddier, Francois J. Bibcode: 2000SPIE.4006..377G Altcode: The nulling stellar coronagraph, first proposed by Roddier and Roddier and later demonstrated in a laboratory experiment is a technique to produce wide-field coronagraphic images. It uses a small phase-shifting mask in the focal plane to remove the central star by destructive interference. When applied to a space-based interferometric array of telescopes, it can be a powerful tool to search for faint companions around nearby stars or image circumstellar disks. A program was written to simulate the performance of a nulling stellar coronagraph for single or multi aperture telescopes in space or on the ground. In this study, we explore some aspects of the use of such a technique. By running our simulation program on various sources, we find that a nulling stellar coronagraph applied on a space interferometer like Darwin or TPF can image Earth-type planets in less than an hour of exposure time. Title: Deconvolution of adaptive optics images: from theory to practice Authors: Conan, Jean-Marc; Fusco, Thierry; Mugnier, Laurent M.; Marchis, Franck; Roddier, Claude A.; Roddier, Francois J. Bibcode: 2000SPIE.4007..913C Altcode: Practical guidelines are proposed for deconvolution of partially adaptive optics corrected images: from raw data to high photometric precision object restoration. Preliminary processing is discussed (detector calibration, background subtraction...). The deconvolution scheme itself is then presented. It takes into account the noise statistics in the image, the imprecise knowledge of the point spread function (PSF), and the available a priori information on the object (spatial structure, positivity...). This deconvolution scheme is first validated on simulated images of NAOS, the AO system of the VLT and then applied to astronomical images. In particular, an edge preserving regularization is tested on several solar system objects: Io, Uranus and Neptune. Title: First light for Hokupa'a 36 on Gemini North Authors: Graves, J. Elon; Northcott, Malcolm J.; Roddier, Francois J.; Roddier, Claude A.; Potter, Dan; O'Connor, Daniel J.; Rigaut, Francois J.; Chun, Mark R. Bibcode: 2000SPIE.4007...26G Altcode: The University of Hawaii adaptive optics program has recently moved its 36 actuators system, named 'Hokupa'a 36', to the Gemini North Telescope. First light for Hokupa'a 36 was in time for the dedication of this telescope during June 1999 and most of the images presented were taken with this adaptive optics system. This paper will cover the modifications to the CFHT, Hokupa'a 36 system that were necessary to accommodate the larger 8 meter aperture of the Gemini Telescope. Performance at the telescope has now been measured and compares favorably with that predicted. Title: Infrared very large array for the 21st century Authors: Ridgway, Stephen T.; Roddier, Francois J. Bibcode: 2000SPIE.4006..940R Altcode: In order to exploit the interferometric resolution advantage to the utmost, an array with a significant number of telescopes and large (and variable) baselines will be required. Achieving the sensitivity needed for a wide range of science opportunities requires large, AO equipped individual apertures. Dual-beam operation will be needed to support good sky coverage. Phasing of the array for resolved sources can be accomplished with wide-band, pair-wise combination, bootstrapping, and phase closure. For the best sensitivity with maximum field of view, the imaging focus must employ direct optical synthesis of the PSF, while for best sensitivity with reduced field-of-view, pupil densification may be used. The suggested concept, for discussion purposes, consists of 27 telescopes of 3.5-m aperture, distributed in a Cornwell circle configuration. Such a facility would most likely have a cost in the range discussed for a next generation large aperture telescope. The technical readiness is good. Title: Design and performance of an 85-actuator curvature system Authors: Northcott, Malcolm J.; Graves, J. Elon; Roddier, Francois J.; Rigaut, Francois J. Bibcode: 2000SPIE.4007..126N Altcode: The UH 36 element curvature AO system, Hokupa'a-36, was recently moved to the Gemini 8m telescope, where it was used with great success obtaining images for the telescope dedication. Since the 36 actuator system was optimized for performance on a 4 m (CFHT) telescope it does not provide full near IR wavelength converge on the Gemini 8m telescope. In order to address this issue we are planning to upgrade the system to 85 actuators. Given the slightly better seeing expected at the Gemini telescope, the move to 85 actuators will give Strehl ratios commensurate to those obtained with 36 actuators on the CFHT. The limiting magnitude will scale with the telescope aperture giving considerably better sky coverage than at the CFHT. Curvature AO systems can scale considerably beyond 85 actuators, at this point technology presents the most important limitations to scaling. Title: Search for asteroidal satellites using adaptive optics Authors: Close, Laird M.; Merline, William J.; Dumas, C.; Chapman, Clark R.; Roddier, Francois J.; Menard, Francois; Slater, David C.; Duvert, Gilles; Shelton, J. Christopher; Morgan, Thomas H. Bibcode: 2000SPIE.4007..796C Altcode: We utilized AO to discover a moon around asteroid 45 Eugenia by use of the PUEO AO facility at CFHT. With PUEO we performed a search for asteroidal satellites among two dozen asteroids, achieving moderate Strehl ratios (35%) and FWHM of about 0.12' at H band. During this survey, we detected a faint close companion to 45 Eugenia. The satellite was 6.14 magnitudes (at 1.65 micrometer) fainter and located at most 0.75' from Eugenia. Without the ability of AO to sharpen the contrast and increase the resolution to 0.1', the detection of this companion would have been impossible with ground-based telescopes. The companion was found to be in a 1200 km circular orbit with a period of 4.7 days. We discovered that the bulk density of the large (215 km) asteroid 45 Eugenia is a surprisingly low 1.2 g/cm3. This has lead to the exciting possibilities that either this main belt asteroid is a burned out comet or has a hollow 'rubble-pile' structure. Title: Adaptive optics imaging of Pluto-Charon and the discovery of a moon around the Asteroid 45 Eugenia: the potential of adaptive optics in planetary astronomy Authors: Close, Laird M.; Merline, William J.; Tholen, David J.; Owen, Tobias C.; Roddier, Francois J.; Dumas, C. Bibcode: 2000SPIE.4007..787C Altcode: We outline two separate projects which highlight the power of adaptive optics (AO) to aid planetary research. The first project utilized AO to discover a moon around asteroid 45 Eugenia by use of the PUEO AO facility at CFHT. We also utilized AO to resolve the Pluto-Charon system by producing 0.15' FWHM images. We used the University of Hawaii AO system (Roddier et al. 1991) at CFHT to obtain deep (20 min) narrow band images in and out of the molecular bands of water and methane ices. Title: NPT: a large-aperture telescope for high dynamic range astronomy Authors: Joseph, Robert D.; Kuhn, Jeff R.; Tokunaga, Alan T.; Coulter, Roy; Ftaclas, Christo; Graves, J. Elon; Hull, Charles L.; Jewitt, D.; Mickey, Donald L.; Moretto, Gilberto; Neill, Doug; Northcott, Malcolm J.; Roddier, Claude A.; Roddier, Francois J.; Siegmund, Walter A.; Owen, Tobias C. Bibcode: 2000SPIE.4005..333J Altcode: All existing night-time astronomical telescopes, regardless of aperture, are blind to an important part of the universe - the region around bright objects. Technology now exist to build an unobscured 6.5 m aperture telescope which will attain coronagraphic sensitivity heretofore unachieved. A working group hosted by the University of Hawaii Institute for Astronomy has developed plans for a New Planetary Telescope which will permit astronomical observations which have never before ben possible. In its narrow-field mode the off-axis optical design, combined with adaptive optics, provides superb coronagraphic capabilities, and a very low thermal IR background. These make it ideal for studies of extra-solar planets and circumstellar discs, as well as for general IR astronomy. In its wide-field mode the NPT provides a 2 degree diameter field for surveys of Kuiper Belt Objects and Near-Earth Objects, surveys central to current intellectual interests in solar system astronomy. Title: Adaptive Optics in Astronomy Authors: Roddier, François; Thompson, Laird Bibcode: 2000PhT....53d..69R Altcode: No abstract at ADS Title: Adaptive Optics Observations of Saturn's Ring Plane Crossing in August 1995 Authors: Roddier, F.; Roddier, C.; Brahic, A.; Dumas, C.; Graves, J. E.; Northcott, M. J.; Owen, T. Bibcode: 2000Icar..143..299R Altcode: Adaptive optics (0.15″ resolution) infrared images of the rings and satellites of Saturn were obtained in August 1995 as the Earth was crossing the ring plane. Twelve clumps were detected in the F ring, including HST S5 and S7 objects. For the first time H magnitudes were obtained for Prometheus, Pandora, Telesto, and Calypso, and J magnitudes for Epimetheus, Janus, Mimas, Telesto, and Helene. Title: Five-Years of Adaptive Optics Observations of T Tau South Authors: Roddier, F.; Roddier, C.; Brandner, W.; Charissoux, D.; Véran, J. -P.; Courbin, F. Bibcode: 2000IAUS..200P..60R Altcode: We describe the results of a five year monitoring of T Tau with adaptive optics. Our main conclusions are: i) the orbital motion of the binary suggests a system mass >= 3.3 Modot, and a minimum mass of 1.3 Modot for T Tau S, which rules out a very-low mass for the infrared companion; ii) based on its near-infrared brightness and color variations, T Tau S can be classified as an EXor-type variable; iii) T Tau S appears to be resolved in the near-infrared AO data. The data are consistent with a star plus an extended envelope. Title: Nulling Stellar Coronagraphic Imaging Using Space Interferometric Arrays Authors: Guyon, O.; Roddier, F. Bibcode: 2000ESASP.451...41G Altcode: 2000dais.conf...41G No abstract at ADS Title: A New Planetary Telescope Concept Authors: Joseph, R. D.; Kuhn, J. R.; Tokunaga, A.; Coulter, R.; Ftaclas, C.; Graves, J. E.; Hull, C.; Jewitt, D.; Mickey, D.; Moretto, G.; Neill, D.; Northcott, M.; Roddier, F.; Roddier, C.; Siegmund, W.; Owen, T. Bibcode: 1999DPS....31.5943J Altcode: 1999BAAS...31.1591J The NASA IRTF is arguably the only ground-based telescope in the world dedicated to planetary astronomy. Two decades of improvement in infrared array technology, adaptive optics, and large mirror fabrication techniques now make it imperative that the future needs of NASA's Planetary Astronomy program be considered in the context of the capabilities now possible for a modern telescope. In response to a suggestion from NASA Headquarters we have developed an innovative telescope concept which provides unique and unsurpassed scientific capabilities to the planetary community. We call this facility the New Planetary Telescope (NPT). We have assumed that the main objectives for the NPT are studies of Kuiper Belt Objects, Near-Earth Objects, studies of circumstellar disks and extra-solar planets, and ground-based support for NASA flight missions. These diverse scientific objectives require capabilities ranging over wide-field imaging, high angular resolution, high sensitivity in the optical and thermal infrared, and superb photometric dynamic range. This study shows that it is possible to achieve all of these performance requirements using a 6.5m unobstructed, off-axis telescope. This concept has compelling natural advantages for adaptive optics, coronagraphic astronomical imaging, and thermal infrared imaging. Unique features of the NPT include wide-field imaging capability, with a field-of-view of at least two degrees, optimization for unprecedented low scattered light and high dynamic range astronomy, extremely low infrared emissivity, and innovative instruments uniquely designed to take full advantage of these capabilities. This telescope concept breaks new ground in telescope technology, and it is therefore an ideal technical development project for NASA. NASA is currently at the forefront of development in interferometry using the Keck telescopes. The NPT complements and enhances this program since it provides an important baseline to add to those already planned on Mauna Kea. Moreover, the NPT is the ideal telescope for a full-fledged optical/infrared array of interferometric telescopes. Title: Adaptive Optics Imaging of Pluto-Charon and the Discovery of a Moon aroun d the Asteroid 45 Eugenia: The Potential of Adaptive Optics in Planetary Astrono my Authors: Close, L. M.; Merline, W. J.; Tholen, D.; Owen, T.; Roddier, F.; Dumas, C. Bibcode: 1999DPS....31.5910C Altcode: 1999BAAS...31.1585C We outline two separate projects which highlight the power of adaptive optics (AO) to aid planetary research. The first project utilized AO to resolve the Pluto-Charon system by producing 0.15" FWHM images. We used the University of Hawaii AO system (Roddier et al. PASP 103, 131,1991) at CFHT to obtain deep (20 min) narrow band images in/out the molecular bands of water and methane ices. Our images confirm that the variation of Pluto's albedo is mainly governed by the presence of methane ice over its surface, resulting in a lower albedo at 2.26 um than at 2.02 um. Our observations confirm also that Charon is mostly covered with water-ice (Buie et al. NATURE 329, 522,1987). See Tholen et al. (ICARUS submitted) for more details on these AO results. In another application of AO, we discovered a moon around asteroid 45 Eugenia by use of the PUEO AO facility at CFHT (Rigaut et al. PASP 110, 152, 1998). With PUEO we preformed a search for asteroidal satellites among two dozen asteroids, achieving moderate Strehl ratios (35%) and FWHM of about 0.12" at H band. During this survey, we detected a faint close companion to 45 Eugenia. The satellite was 6.14 magnitudes (at 1.65 um) fainter and located at most 0.75" from Eugenia. Without the ability of AO (to sharpen the contrast and increase the resolution to 0.1"), the detection of this companion would have been impossible with ground based-telescopes. The companion was found to be in a 1200 km circular orbit with a period of 4.7 days. A more detailed discussion of this new satellite is given by Merline et al. in this volume. Adaptive optics is entering a powerful new age as all the major ground based large telescopes are developing facility AO systems. Planetary astronomy is particularly well posed to take advantage of the diffraction-limited, near-IR images (0.050" FWHM) that will become commonplace at all 8 m facilities in the near future (It is already occurring on the KECK and GEMINI-North telescopes). In particular, we review plans for the NAOS/CONICA AO facility instrument at the ESO 8m VLT that will have first light in late 2000. It is planned that NAOS/CONICA will obtain K-band Strehl ratios of 60% with reference objects (extended up to 3") of brightness V=13 (or brighter). The instrument will allow guiding on faint V=15 sources (with Strehls 20 well as tracking planetary targets that have a velocity different from the guide source. The ability to carry out remote service observing and an automatic data reduction pipeline will make the ESO VLT AO system ideal for monitoring temporal changes in planetary targets and carrying out targets of opportunity programs in general. These AO observations were made possible by support from the NSF, NASA, SwRI, and ESO. Title: Adaptive Optics Imaging and Spectroscopy of MWC 1080 Authors: Brandner, W.; Close, L.; Graves, B.; Northcott, M.; Potter, D.; Roddier, C.; Roddier, F.; Tokunaga, A.; Dekany, R.; Troy, M.; Brandl, B.; Hayward, T.; Bloemhof, E. E.; Gaidos, E.; Oppenheimer, B. R. Bibcode: 1999AAS...195.0212B Altcode: 1999BAAS...31.1368B We present adaptive optics near-infrared observations of the Herbig AeBe binary MWC 1080 and its associated cluster of low-mass stars. The adaptive optics data have been obtained with the 13 element curvature sensing AO system, an optical CCD camera and the NIR camera QUIRC at the CFHT 3.6m telescope, and with the 349/241 element Shack-Hartmann AO system PALAO and the NIR camera PHARO at the Palomar 200'' (5m) telescope. The primary and its about 3mag fainter companion are clearly detected and resolved at all wavebands from I to K. Spatially resolved K-band spectra of both components of the 0.7'' binary allow us for the first time to derive individual spectral types for both components. In addition to the central binary, the NIR data reveal about 30 faint sources within 30'' of MWC 1080. The sources exhibit various degrees of IR excess and appear to be young low-mass stars associated with MWC 1080. By comparison with theoretical pre-main sequence evolutionary tracks we are able to assign masses and ages. Narrow-band emission line images in Brγ and H2 are used to identify outflow features and shocks. The high-spatial resolution data reveal that the bipolar, hourglass shaped outflow cavity around MWC 1080 is illuminated by scattered light. The pinched in, narrow waist of the hourglass can be explained by a density gradient in the circumstellar medium, possibly due to a circumstellar disk around MWC 1080. This research is supported by NSF and NASA. Title: The Next-Generation Optical/IR Array Authors: Ridgway, S. T.; Roddier, F. Bibcode: 1999AAS...195.2305R Altcode: 1999BAAS...31.1407R Increasingly intense activity in optical interferometry over the past two decades has led to the development and exploitation of numerous prototype arrays. As interferometry gains in technical maturity, science oriented facilities are beginning to come on-line, with at least 6 to be operational within a few years. These facilities offer major advances in performance. Each is, however, relatively specialized, or distinctly limited in some respects. Therefore, it appears to us timely to consider the possible configuration of a next generation array. In order to exploit the interferometric resolution advantage to the utmost, an array with a significant number of telescopes and large (and variable) baselines will be required. Achieving the sensitivity needed for a wide range of science opportunities requires large, AO equipped individual apertures. The suggested concept, for planning and budgeting purposes, consists of 27 telescopes of 3.5-m aperture, distributed in a Cornwell circle configuration. Such a facility would most likely have a cost in the range discussed for a next generation large aperture telescope. The technical readiness is excellent. With an array size of 1 kilometer, J band angular resolution would be 200 microarcsec, and characterization of sources as small as 20 microarcsec would be possible. Very high resolution interferometric imaging will enable detailed study of compact solar system, stellar, galactic, extragalactic and cosmological sources. The potential for studies of normal and active galactic nuclei, interacting binaries, and YSO's, are particularly promising. This paper was prepared for presentation to the National Academy Decade Survey of Astronomy and Astrophysics, and profited from the advice of many colleagues. Title: "High Angular Resolution Observations of Protoplanetary Disks with Adaptive Optics" Authors: Roddier, Francois Bibcode: 1999STIN...0004764R Altcode: Significant results were obtained and published in the literature. The first optical detection of a circumbinary disk was reported in the ApJ at millimetric wavelengths. The size and inclination of this disk were found to be consistent with millimetric observations. Evidence was found for a cavity inside the disk as theory predicts from dust clearing by the stellar companion. Title: An Adaptive Optics search for Low Mass Companions in the Ursa Major Stream Authors: Potter, D. E.; Tokunaga, A. T.; Close, L. M.; Graves, J. E.; Northcott, M. J.; Roddier, F.; Roddier, C.; Kobayashi, N. Bibcode: 1999AAS...19510905P Altcode: 1999BAAS...31.1534P We report the current status of an ongoing search for low mass companions in the Ursa Major stream using the U. of Hawaii adaptive optics (AO) system, Hokupa'a, and the CFHT user AO instrument, PUEO. The high spatial resolution (FWHMH=0.12 arcsec), high dynamic range (107 at 3 arcsec) AO images of more than half of the Ursa Majoris stream have been obtained in a search for faint companions to these nearby ( 25pc), young ( 0.3 Gyr) stars. The data from these observations were image processed and Fourier filtered to enhance point source detection in real time at the telescope using a quick reduction software package written in IDL. The faint point sources detected in the field are compared to a star count model of the galaxy which estimates their probability as background stars. Title: Discovery of a moon orbiting the asteroid 45 Eugenia Authors: Merline, W. J.; Close, L. M.; Dumas, C.; Chapman, C. R.; Roddier, F.; Menard, F.; Slater, D. C.; Duvert, G.; Shelton, C.; Morgan, T. Bibcode: 1999Natur.401..565M Altcode: No abstract at ADS Title: The Nulling Stellar Coronagraph: Laboratory Tests and Performance Evaluation Authors: Guyon, Olivier; Roddier, Claude; Graves, J. Elon; Roddier, François; Cuevas, Salvador; Espejo, Carlos; Gonzalez, Salustio; Martinez, Andrea; Bisiacchi, Gianfranco; Vuntesmeri, Valeri Bibcode: 1999PASP..111.1321G Altcode: The nulling coronagraph, first proposed by Roddier and Roddier, uses a small mask (less than half the size of the central Airy spot) that shifts the phase of the incoming light by 180 deg to strongly attenuate the Airy spot as well as the rings. We report on both theoretical and laboratory performance. In our laboratory experiment, we reduce the peak intensity of the Airy pattern by a factor of 16. We derive estimates of the performance of a nulling coronagraph used on a telescope equipped with an adaptive optics system, based upon the performance of the University of Hawaii Hokupa'a adaptive optics system. On a 3.6 m telescope at 1.65 μm, it is found that a tip/tilt amplitude lower than 20 mas is needed for such a coronagraph to yield an extinction better than 2 stellar mag. Title: Discovery of asteroidal satellite S/1998 (45) 1. Authors: Merline, W. J.; Close, L. M.; Dumas, C.; Chapman, C. R.; Roddier, F.; Ménard, F.; Colwell, W. B.; Slater, D. C.; Duvert, G.; Shelton, C.; Morgan, T. H. Bibcode: 1999BAAS...31.1106M Altcode: No abstract at ADS Title: Discovery of Asteroidal Satellite S/1998 (45) 1 Authors: Merline, W. J.; Close, L. M.; Dumas, C.; Chapman, C. R.; Roddier, F.; Menard, F.; Colwell, W.; Slater, D. C.; Duvert, G.; Shelton, C.; Morgan, T. Bibcode: 1999DPS....31.2006M Altcode: On 1998 November 1, we performed the first imaging of an asteroidal satellite from Earth-based observatories, when we detected a moon of asteroid (45) Eugenia. Provisionally designated S/1998 (45) 1, the satellite has a diameter of about 13 km and orbits the 215-km primary at a distance of about 1200 km. The orbit is near-circular and has a period of 4.7 days. Our observations show the object on 5 nights, spanning two continuous orbital cycles, and it was again detected two months later. At the time of discovery, the satellite was found to be about 6 magnitudes fainter than Eugenia, with a separation of 0.75 \arcsec; the orbit was inclined to the line-of-sight by 45{\char'27}. Our analysis suggests that the orbit is prograde (i.e., the orbit and the primary spin are in the same sense) and lies approximately in Eugenia's equatorial plane. Our measurements yield a tentative (because of the uncertain size of Eugenia) bulk density of this C-like asteroid of about 1.2 g cm(-3) , implying that it may be structurally and/or compositionally similar to the C-type asteroid Mathilde, whose density was determined from the flyby of the NEAR spacecraft to be 1.3 g cm(-3) . We discuss the implications of these findings for the composition and structure of Eugenia and for the mechanisms for satellite formation. We place these findings in the context of an additional 25 asteroids for which we have similar data, and in the context of asteroid families and taxonomic types. These observations were made using near-infrared (H-band at 1.65 mu ) direct imaging, with the adaptive optics system (PUEO) of the 3.6-m Canada-France-Hawaii Telescope (CFHT) on Mauna Kea. This is the first positive detection from a comprehensive program, funded by NASA and NSF, to survey up to 200 asteroids for the presence of companions. The program is carried out using the adaptive optics systems of CFHT and the Mt. Wilson 100" telescope. Title: Images of Neptune's ring arcs obtained by a ground-based telescope Authors: Sicardy, B.; Roddier, F.; Roddier, C.; Perozzi, E.; Graves, J. E.; Guyon, O.; Northcott, M. J. Bibcode: 1999Natur.400..731S Altcode: Neptune has a collection of incomplete narrow rings, known as ring arcs, which should in isolation be destroyed by differential motion in a matter of months. Yet since first discovered by stellar occultations in 1984, they appear to have persisted, perhaps through a gravitational resonance effect involving the satellite Galatea. Here we report ground-based observations of the ring arcs, obtained using an adaptive optics system. Our data, and those obtained using the Hubble Space Telescope (reported in a companion paper), indicate that the ring arcs are near, but not within the resonance with Galatea, in contrast to what is predicted by some models. Title: Filling Factor and Signal-to-Noise Ratios in Optical Interferometric Arrays Authors: Roddier, François; Ridgway, Stephen T. Bibcode: 1999PASP..111..990R Altcode: Signal-to-noise ratios are derived for an interferometric array of N diffraction-limited optical/IR telescopes with a Fizeau-type beam recombination. We consider two types of objects-extended sources and point sources-and three sources of noise-signal photon noise, sky background noise, and detector noise. We compare the results with that of a filled aperture, and also to that of an incoherent array, each with the same total collecting area. Implications are briefly discussed. Title: S/1998 (45) 1 Authors: Merline, W. J.; Close, L. M.; Dumas, C.; Chapman, C. R.; Roddier, F.; Menard, F.; Slater, D. C.; Duvert, G.; Shelton, C.; Morgan, T.; Dunham, D. W. Bibcode: 1999IAUC.7129....1M Altcode: 1999IAUC.7129Q...1M; 1999IAUC.7129A...1M W. J. Merline, Southwest Research Institute, Boulder, reports for a large collaboration (including L. M. Close, C. Dumas, C. R. Chapman, F. Roddier, F. Menard, D. C. Slater, G. Duvert, C. Shelton, and T. Morgan) the discovery of a satellite of (45) Eugenia on 1998 Nov. 1.5 UT from H-, J-, and K'-band direct imaging with the 3.6-m Canada-France-Hawaii Telescope (+ PUEO adaptive- optics system) on Mauna Kea. The satellite is about 6 mag fainter than (45) and was tracked intermittently on five nights over a 10-day span. Merline et al. derive a near-circular orbit with a period of about 4.7 days, inclined to the line-of-sight by about 45 deg, with a maximum elongation of about 0".8. The satellite was recovered with the CFHT on 1999 Jan. 4. An occultation around Mar. 27.13 of the star CMC 804951 (mag 11.9) by (45) was predicted by D. W. Dunham, but this is likely to be visible only near the earth's north-polar regions (see updates at http://members.home.net/dega/astchart.htm). Title: Rings of Neptune Authors: Roddier, C.; Roddier, F.; Graves, J. E.; Guyon, O.; Northcott, M. J.; Sicardy, B. Bibcode: 1999IAUC.7108....3R Altcode: 1999IAUC.7108C...1R; 1999IAUC.7108S...1R C. Roddier, F. Roddier, J. E. Graves, O. Guyon, and M. J. Northcott, Institute for Astronomy, University of Hawaii (UH); and B. Sicardy, Paris Observatory, report: "Infrared (1.72-micron) images of Neptune taken on 1998 July 6 with the UH adaptive optics system (Hokupa'a) mounted on the Canada-France-Hawaii 3.6-m telescope have been studied further. In addition to the observations of Neptune arcs reported on IAUC 7051, evidence is now found for another ring structure even closer to Neptune. Its radial distance is that of the Le Verrier ring. It is visible only on the west ansa, and its brightness is roughly twice that of the Adams arcs." Title: Ground-Based Interferometry with Adaptive Optics Authors: Roddier, F. Bibcode: 1999ASPC..194..318R Altcode: 1999wfoi.conf..318R Adaptive optics now routinely produces high dynamic range diffraction-limited images on ground-based telescopes using guide sources as far as 10 to 15 arcsec away from the object of interest. The same principles and techniques apply to telescope arrays. A dual-beam interferometer would allow the use of a bright guide source to compensate the wave-front and track the fringes, while observing much fainter nearby sources. Even a single beam interferometer should also have two channels, one for wave-front control, and another one for science. A dichroic beam splitter is then used to separate the two beams. Wave-front control is done with low-noise, fast parallel read-out detectors collecting photons over a very wide spectral band. Wave-front `curvature' sensing is particularly attractive to control an array of telescopes. This can be done by using a single membrane modulator as a common reference, but several detector arrays (one per telescope). In this case, closing the loop will automatically co-align and co-focus all the telescopes as if it were a single aperture. Co-phasing the array still requires an additional sensor (fringe tracker) to sense the wave-front `piston' modes. Because most of the scientific information is obtained under very low fringe visibilities, fringe tracking must be done either at a longer wavelength or - in case of an array - between adjacent apertures. The co-phasing of a large array then becomes the adaptive optics equivalent of reconstructing the wave-front phase from an array of phase differences. Once individual wave-fronts are compensated, co-focused, co-aligned, and co-phased, then it becomes possible to record long exposure interferograms for science applications. Title: Adaptive Optics Imaging of Solar System Objects Authors: Roddier, Francois; Owen, Toby Bibcode: 1999STIN...0025316R Altcode: Most solar system objects have never been observed at wavelengths longer than the R band with an angular resolution better than 1". The Hubble Space Telescope itself has only recently been equipped to observe in the infrared. However, because of its small diameter, the angular resolution is lower than that one can now achieved from the ground with adaptive optics, and time allocated to planetary science is limited. We have successfully used adaptive optics on a 4-m class telescope to obtain 0.1" resolution images of solar system objects in the far red and near infrared (0.7-2.5 microns), aE wavelengths which best discl"lmlnate their spectral signatures. Our efforts have been put into areas of research for which high angular resolution is essential. Title: Planetary Science with Adaptive Optics: Results from the UH AO Systems Authors: Roddier, F.; Roddier, C.; Close, L.; Dumas, C.; Graves, J. E.; Guyon, O.; Han, B.; Northcott, M. J.; Owen, T.; Tholen, D.; Brahic, A. Bibcode: 1999ESOC...56..401R Altcode: 1999aaop.conf..401R No abstract at ADS Title: Future expectations Authors: Roddier, F. Bibcode: 1999aoa..book..399R Altcode: No abstract at ADS Title: The UH-CFHT systems Authors: Roddier, F.; Rigaut, F. Bibcode: 1999aoa..book..205R Altcode: No abstract at ADS Title: Adaptive Optics J Band Imaging Polarimetry Observations of the Circumbinary Disk Around UY Aurigae Authors: Potter, D. E.; Close, L. M.; Roddier, F.; Roddier, C.; Graves, J. E.; Northcott, M. Bibcode: 1999ESOC...56..353P Altcode: 1999aaop.conf..353P No abstract at ADS Title: Four-Year Observations of T Tauri With Adaptive Optics Authors: Roddier, C.; Roddier, F.; Graves, J. E.; Northcott, M. J.; Close, L.; Surace, J.; Veran, J. P. Bibcode: 1999ESOC...56..389R Altcode: 1999aaop.conf..389R No abstract at ADS Title: The Nulling Coronograph Authors: Guyon, O.; Roddier, C.; Elon Graves, J.; Roddier, F.; Cuevas, S.; Espejo, C.; Martinez, A.; Gonzales, S.; Bisiacchi, G.; Vuntersmeri, V. Bibcode: 1999ESOC...56..537G Altcode: 1999aaop.conf..537G No abstract at ADS Title: Theoretical aspects Authors: Roddier, F. Bibcode: 1999aoa..book...25R Altcode: No abstract at ADS Title: Historical context Authors: Roddier, F. Bibcode: 1999aoa..book....3R Altcode: No abstract at ADS Title: The nulling coronagraph applied to interferometric arrays Authors: Guyon, O.; Roddier, F. Bibcode: 1999ASPC..194..201G Altcode: 1999wfoi.conf..201G The nulling stellar coronagraph, first proposed by Roddier and Roddier (PASP 109, p. 815, 1997), uses a small phase mask to shift by 180 degrees the phase of the central part of the Airy spot. This leads to destructive interference which strongly attenuates the central Airy spot as well as the rings, as demonstrated by the result of an experiment we carried out on an optical bench (Guyon et al., PASP submitted). The nulling coronagraph can also be used on an interferometric array by first densifying the entrance pupil (Labeyrie, A&A Supl., 118, p. 517, 1996). The pupil is then rediluted to avoid the narrowing of the field of view. This is the only known nulling technique that produces a true undisturbed image with the central bright star removed. Numerical simulations allow us to evaluate the performance of this nulling technique with different geometrical configurations of subapertures. Title: Imaging through the atmosphere Authors: Roddier, F. Bibcode: 1999aoa..book....9R Altcode: No abstract at ADS Title: Adaptive optics in astronomy Authors: Roddier, Francois Bibcode: 1999aoa..book.....R Altcode: Adaptive optics is a powerful new technique used to sharpen telescope images blurred by the Earth's atmosphere. This authoritative book is the first dedicated to the use of adaptive optics in astronomy. Mainly developed for defence applications, the technique of adaptive optics has only recently been introduced in astronomy. Already it has allowed ground-based telescopes to produce images with sharpness rivalling those from the Hubble Space Telescope. The technique is expected to revolutionise the future of ground-based optical astronomy. Written by an international team of experts who have pioneered the development of the field, this timely volume provides both a rigorous introduction to the technique and a comprehensive review of current and future systems. It is set to become the standard reference for graduate students, researchers and optical engineers in astronomy and other areas of science where adaptive optics is finding exciting new applications. Title: Astronomy with Adaptive Optics: Experiences from the University of Hawaii AO Program Authors: Close, L. M.; Roddier, F.; Potter, D.; Roddier, C.; Graves, J. E.; Northcott, M. Bibcode: 1999ESOC...56..109C Altcode: 1999aaop.conf..109C No abstract at ADS Title: NOTE: Neptune's Cloud Structure and Activity: Ground-Based Monitoring with Adaptive Optics Authors: Roddier, F.; Roddier, C.; Graves, J. E.; Northcott, M. J.; Owen, T. Bibcode: 1998Icar..136..168R Altcode: Since August 1995, near-infrared images of Neptune have regularly been obtained with the University-of-Hawaii telescope. These images reveal Neptune's cloud structure with an angular resolution reaching 0.12″ in the H band. Title: Discovery of an Arc of Particles near Enceladus' Orbit: A Possible Key to the Origin of the E Ring Authors: Roddier, C.; Roddier, F.; Graves, J. E.; Northcott, M. J. Bibcode: 1998Icar..136...50R Altcode: High angular resolution (adaptive optics) images taken on August 12, 1995 between 11:26 and 12:23 (UT) show a faint elongated structure apparently moving away from Saturn. The structure is consistent with light scattered by an arc of particles on a Keplerian orbit close to that of Enceladus. The orbit is slightly inclined (1.8°), and the arc is 76° ahead of the satellite. It appears to be a transient phenomenon since the arc brightness decreased by almost a factor two during the observations, and no such structure was observed at the same orbital position two days before. A possible explanation is that a large block of ice previously ejected by Enceladus collided with ice fragments trapped on the satellite orbit near its L4Lagrange point. The collision likely occurred about 6 h before observations started and produced a rapidly expanding cloud of small particles. We estimate the total mass of particles to be at least 105kg. Title: Satellites and Rings of Neptune Authors: Roddier, C.; Roddier, F.; Graves, J. E.; Guyon, O.; Northcott, M. J.; Sicardy, B. Bibcode: 1998IAUC.7051....1R Altcode: 1998IAUC.7051Q...1R C. Roddier, F. Roddier, J. E. Graves, O. Guyon, and M. J. Northcott, Institute for Astronomy, University of Hawaii (UH); and B. Sicardy, Paris-Meudon Observatory, report: "Infrared (1.72- micron) images of Neptune taken on July 6 with the UH adaptive optics system (Hokupa'a) mounted on the Canada-France-Hawaii 3.6-m telescope have now been thoroughly processed. In addition to the observations of Neptune VI (Galatea), VII (Larissa), and VIII (Proteus) reported on IAUC 6987, Neptune V (Despina) and Neptune's ring arcs have also been detected. Despina, which was far from maximum elongation, moved substantially during the 600-s exposure time, but its average position is consistent within +/- 1 deg of that estimated from Voyager 2 data in 1989 (as for Proteus and Larissa). Each of the three brightest arcs Liberte, Egalite, and Fraternite are identified. The fainter leading arc Courage cannot be confirmed. The positions of the main arcs are close to that given by the second orbital solution of Nicholson et al. (1995, Icarus 113, 295), which corresponds to a mean motion of 820.1118 deg/day. Photometric profiles of the arcs have been obtained and compared with those of Porco (1991, Science 253, 995), allowing for the blur due to our 600-s integration time. For the two trailing arcs (Fraternite and Egalite), the fit is very good. It shows that the arcs are 4 +/- 2 deg ahead of the position estimated from Nicholson's second solution. For Liberte the uncertainty is larger due to noise. Four 200-s exposures made in the J band were also analyzed. The arcs were not detected. However, the data confirm that Galatea is 5 +/- 1 deg ahead of the nominal predicted position (IAUC 6987). In these data, Despina is closer to maximum elongation. Its image is sharper and its position is again consistent within +/- 1 deg with that predicted from Voyager data. We note that the uncertainties in the orbital parameters derived from Voyager data by Owen et al. (1991, A.J. 101, 1511) lead to the following standard errors on the current satellite longitudes: +/- 2.9 deg for Proteus, +/- 5.2 deg for Larissa, +/- 9.1 deg for Despina, and +/- 8.1 deg for Galatea. The estimated errors are believed to be conservative by typically a factor of two (ibid.). Further analysis is thus required to see if the Galatea O-C is significant or a mere effect of the accumulation of error between 1989 and 1998." Title: University of Mexico adaptive optics program Authors: Cuevas, Salvador; Sotelo, Pablo D.; Garfias, Fernando; Iriarte, Arturo; Martinez, Luis A.; Orlov, Valeri G.; Voitsekhovich, Valeri V.; Chapa, O.; Tinoco, Silvio J.; Vernin, Jean; Avila, Remy; Marchis, Franck; Graves, J. Elon; Northcott, Malcolm J.; Roddier, Francois J.; Roddier, Claude A. Bibcode: 1998SPIE.3353..531C Altcode: We describe different works conducing to the adaptive optics system for the TIM 6.5m telescope. We show turbulence profiles result at our San Pedro Martir Observatory in Baja using the Generalized SCIDAR. We can conclude that the turbulence conditions in this site are comparable to the major observatories in the world. From these results and taken in account curvature AO simulations it is possible to predict the performances in limiting magnitude and sky coverage of different AO systems and telescopes in our observatory. We can also define the degree of the AO system for the TIM 6.5m telescope. We made a short description of our LOLA tip-tilt corrector system and the GUIELOA 19 elements curvature AO system. The calculation of the optics quality for the TIM 6.5m is briefly mentioned. Studies about the influence of the finite outerscale on the optical quality of AO corrected images are described. Title: Wavefront curvature sensing on extended arbitrary scenes: simulation results Authors: Kupke, Renate; Roddier, Francois J.; Mickey, Donald L. Bibcode: 1998SPIE.3353..918K Altcode: We describe and evaluate the performance of a wavefront sensor based on curvature sensing which can be used to detect static aberrations given an extended reference source. The description includes a full mathematical treatment of the sensor signal, as well as how this signal is relate to the Laplacian of the wavefront. Evaluation of the technique is performed with computer simulations. A Monte-Carlo simulation is utilized to evaluate the performance of the technique in the presence of noise. The sensor was found to provide accurate measurement of the wavefront coefficients on high-contrast extended objects. It behaves well in the presence of a field stop, and in the presence of additive Gaussian noise. Title: First light for Hokupa'a: 36-element curvature AO system at UH Authors: Graves, J. Elon; Northcott, Malcolm J.; Roddier, Francois J.; Roddier, Claude A.; Close, Laird M. Bibcode: 1998SPIE.3353...34G Altcode: The University of Hawaii adaptive optics program has scaled its previously successful 13 elements AO system to 36 actuators and named it 'Hokupa'a', meaning 'immovable star' in Hawaiian. First light for Hokupa'a in early November of 1997, was on the Canada France Hawaii Telescope on Mauna Kea, an f/35, 3.35 meter telescope. Performance at the telescope has now been measured and compares favorably with that predicted theoretically. The extension to 36 elements has now allowed the system to give diffraction limited performance down to I band on stars as faint as 12.5 magnitude in median 0.7 arcsecond seeing on Mauna Kea. Like our previous system, extensive computer simulations were carried out to achieve the best possible match between the curvature WFS and the deformable curvature mirror. Title: Scientific results from the University of Hawaii: adaptive problems well suited to AO techniques Authors: Close, Laird M.; Roddier, Francois J.; Roddier, Claude A.; Graves, J. Elon; Northcott, Malcolm J.; Potter, Dan Bibcode: 1998SPIE.3353..406C Altcode: The University of Hawaii AO group has been actively carrying out astronomical AO observations for the last four years. The UHAO group and out collaborators have utilized the curvature AO system to obtain diffraction-limited images of asteroids, planets, moons, protoplanetary disks, young stars, young star clusters, planetary nebulae, black holes, galaxies and quasars. The current scientific capabilities of the new 36-actuator Hokupa'a AO curvature system will be briefly reviewed. Four key astronomical situations that are excellent for AO observations will be discussed. Examples of scientific observational techniques will be highlighted with actual AO astronomical results. Title: Satellites of Neptune Authors: Roddier, C.; Roddier, F.; Graves, J. E.; Guyon, O.; Northcott, M. J. Bibcode: 1998IAUC.6987....2R Altcode: 1998IAUC.6987B...1R; 1998IAUC.6987R...1R C. Roddier, F. Roddier, J. E. Graves, O. Guyon, and M. J. Northcott, Institute for Astronomy, University of Hawaii (UH), report: "Infrared (1.72-micron) images of Neptune were taken on July 6 with the UH adaptive optics system (Hokupa'a) mounted on the Canada-France-Hawaii telescope. Neptune VIII (Proteus), VII (Larissa), and VI (Galatea) were detected and observed from July 6.490 to 6.552 UT. Whereas Proteus and Larissa were found to be at their expected position, Galatea was found to be 5 +/- 1 degrees ahead of the predicted position (8.6 min early), a difference possibly due to its interaction with Neptune's Adams ring (cf. Ferrari and Brahic 1994, Icarus 111, 193; Hanninen and Porco 1997, Icarus 126, 1)." Title: Maximum Gain and Efficiency of Adaptive Optics Systems Authors: Roddier, François Bibcode: 1998PASP..110..837R Altcode: A definition is given for the efficiency of an adaptive optics (AO) system. An expression is derived that allows the efficiency of an AO system to be simply estimated. Estimates are derived for the efficiency of several AO systems currently used in astronomy. The advantages of building high-efficiency systems are emphasized. Title: Adaptive Optics Imaging of the Circumbinary Disk around the T Tauri Binary UY Aurigae: Estimates of the Binary Mass and Circumbinary Dust Grain Size Distribution Authors: Close, L. M.; Dutrey, A.; Roddier, F.; Guilloteau, S.; Roddier, C.; Northcott, M.; Ménard, F.; Duvert, G.; Graves, J. E.; Potter, D. Bibcode: 1998ApJ...499..883C Altcode: We have obtained high-resolution (FWHM = 0.15") deep images of the UY Aur binary at J, H, and K' with the University of Hawaii adaptive optics instrument. We clearly detect an R ~ 500 AU circumbinary disk discovered with millimeter interferometry, making UY Aur the second young binary with a confirmed circumbinary disk. It appears that the disk is inclined ~42° from face on. We find that the near side of the disk is brighter than the far side by factors of 2.6, 2.7, and 6.5 times at K', H, and J, respectively. The original GG Tau circumbinary disk has been reexamined and is found to have similar flux ratios of 1.5, 2.6, and 3.6 at K', H, and J, respectively. A realistic power-law distribution (p = 4.7) of spherical dust aggregates (composed of silicates, amorphous carbon, and graphite) that reproduces the observed ISM extinction curve also predicts these observed flux ratios from Mie scattering theory. We find the observed preference of forward-scattering over back-scattering is well fitted (global χ2 minimization) by Mie scattering off particles in the range amin = 0.03 μm to amax = 0.5-0.6 μm. The existence of a significant population of grain radii larger than 0.6 μm is not supported by the scattering observations.

Based on the observed disk inclination we derive an orbit for UY Aur where the mass for the binary is 1.6+0.47-0.67 M⊙. Based on the observed K7 and M0 spectral types for UY Aur A and B, accretion disk models for the inner disks around the central stars were constructed. The models suggest that small (lower limit R ~ 5-10 AU) inner disks exist around B and A. It appears that B is accreting ~5 times faster than A, and that both inner disks may be exhausted in ~102-103 yr without replenishment from the outer circumbinary disk. Our images suggest that these inner disks may indeed be resupplied with material through thin streamers of material that penetrate inside the circumbinary disk. Currently it appears that such a streamer may be a close to UY Aur B. Comparison of our IR images and the millimeter images of the gas clearly show that the dust seen in our IR images traces the gas in the circumbinary disk, as was also the case with GG Tau. Title: Adaptive Optics Provides a Sharp Image of Io's Volcanoes Authors: Dumas, C.; Close, L.; Graves, B.; Northcott, M.; Roddier, F.; Hainaut, O.; Connelley, M. Bibcode: 1998BCFHT..38...26D Altcode: No abstract at ADS Title: A Model of Scattering from Dust in Proto-planetary Disks applied to O.1" resolution U. of Hawaii Adaptive Optics Images of the Disk around Young Stars Authors: Potter, D. E.; Close, L.; Roddier, F. Bibcode: 1997AAS...191.0503P Altcode: 1997BAAS...29.1213P We present a method for using the infrared extinction profile and observed scattered infrared radiation from dust in proto-planetary disks to obtain constraints on the dust grain size distribution, density profile, inclination, and extent of the disk. Our method utilizes a Mie scattering algorithm which calculates the exact scattering angle probabilities for light incident on a homogeneous sphere. The dielectric properties of the dust used in the modeling are that of a realistic mix of silicate, amorphous carbon, graphite, and vacuum. The code produces disk images and extinction values from given inclination angles, dust size and density distributions, wavelengths, and flaring profiles. Parameter fitting routines can thus be carried out between these models and high resolution observations to constrain the parameter values of the observed disks. The recently obtained University of Hawaii adaptive optics images of UY Aur and GG Tau resolve circumbinary disks in both systems. We apply our method to the intensity distributions revealed by the images to constrain the particle size distributions and densities for both systems. We obtain good fits to both the extinction profile and the observed intensity variations on the front and back side of the disk with a rather steep ( ~ -4.7) power law distribution and a range of dust sizes ranging from 0.03 and 0.6 microns. A significant population of grains larger than 0.6 microns is not supported by the observations. Title: Adaptive Optics Infrared Imaging Polarimetry and Optical HST Imaging of Hubble's Variable Nebula (R Monocerotis/NGC 2261): A Close Look at a Very Young Active Herbig Ae/Be Star Authors: Close, L. M.; Roddier, F.; Hora, J. L.; Graves, J. E.; Northcott, M.; Roddier, C.; Hoffman, W. F.; Dayal, A.; Fazio, G. G.; Deutsch, L. K. Bibcode: 1997ApJ...489..210C Altcode: We present high-resolution (FWHM = 0.2") near-IR (J, H, and K') adaptive optics images of the Herbig Ae/Be star R Monocerotis. Optical Hubble Space Telescope (HST) WFPC2 PC camera archival images are also presented. For the first time, adaptive optics was utilized to make high-resolution (FWHM = 0.2") IR-imaging polarimetry maps of R Mon. In addition, the first mid-IR array images (at 11.7 and 20.8 μm) of R Mon have been obtained. We also present new 3.16, 3.93, and 4.67 μm images.

We have found that R Mon is a 0.69" binary star with a companion that dereddens onto the classical T Tauri locus. Based on the near-infrared photometry of this companion we believe it is a 1.5 M⊙, very young (<3 × 105 yr) classical T Tauri star. The close presence of a young companion suggests that R Mon itself is a rare example of a very young isolated massive star.

At the highest resolutions, R Mon is revealed to be extended by ~0.1" east-west, and ~0.05" north-south in the visible. The young R Mon star is not directly visible in the optical but appears as a resolved conical reflection nebula in scattered light. At infrared wavelengths, the dense circumstellar dust is penetrated and R Mon appears to be an unresolved point source located at 0.06" +/- 0.02" south of the peak optical flux.

The large-scale optical-IR morphology of R Mon and its large reflection nebula (NGC 2261) suggests a thin bipolar parabolic shell of dust. The appearance of the parabolic shell is consistent with an inclination of 20° +/- 10° from the plane of the sky. This inclination implies that R Mon is located 760+800-280 pc distant based on previous proper-motion and radial velocity measurements of R Mon's jet. Our high-resolution (FWHM ~ 0.2") adaptive optics infrared polarimetry maps agree with the current interpretation that NGC 2261 is a reflection nebula illuminated by R Mon.

Interior to the parabolic shell there is a complex of twisted filaments along the eastern edge. These filaments resemble a double-helical structure which is well described by a power law from ~103 to 105 AU from R Mon. This double helix may trace a twisted magnetic field above R Mon.

Based on H I emission-line ratios, we find the direct extinction toward R Mon to be AV = 13.1 mag in the infrared (λ > 1.28 μm), falling to a lower value of AV = 3.6 mag in the optical (λ < 1.28 μm), where scattered light increasingly lowers the effective extinction in the line ratios. The large AV = 13.1 extinction is likely due to the dusty atmosphere of an inclined R ~ 100 AU optically thick accretion disk surrounding R Mon. A simple model of such an accretion disk + star system (with Macc ~ 8 × 10-5 M⊙ yr-1, M* = 10.4 M⊙, R* = 2 R⊙, and T* ~ 3.5 × 104 K) reproduces the observed dereddened R Mon spectral energy distribution (SED) from the optical (0.4 μm) to the millimeter region. Consideration of the lower extinction (AV = 3.6) on the path followed by the scattered visible light eliminated any need for an inner ``gap'' in the accretion disk model to reproduce the SED.

In general, young stellar objects (YSOs) that are obscured in the optical but directly visible in the infrared will have different effective optical and infrared extinctions. Infrared extinctions derived from optical observations dominated by scattered light will be underestimates of the true IR extinction along the direct path. The use of an independent estimator of both the optical and infrared extinctions such as common upper-level H I recombination lines is highly desirable. The utilization of the correct optical and infrared extinctions may relieve the need for optically thin inner-disk gaps to explain YSO near-IR SEDs. Title: First ground-based adaptive optics observations of Neptune and Proteus Authors: Roddier, F.; Roddier, C.; Brahic, A.; Dumas, C.; Graves, J. E.; Northcott, M. J.; Owen, T. Bibcode: 1997P&SS...45.1031R Altcode: High angular resolution (0.15″) K-band images of Neptune were obtained in August 1995, with the University-of-Hawaii adaptive optics system mounted on the 3.6m Canada-France-Hawaii telescope. The images show bright high contrast features that are believed to be high altitude clouds. They confirm that low latitude (<30°) cloud activity has shifted since Voyager from the south hemisphere to the north hemisphere, whereas higher latitude activity seems more permanent. Proteus can be seen at the locations predicted from Voyager data. Its K-magnitude is 19.0±0.03. The corresponding geometrical albedo is identical to that measured in the visible by Voyager. Title: Saturn Authors: Roddier, C.; Roddier, F.; Graves, J. E.; Northcott, M. J. Bibcode: 1997IAUC.6697....1R Altcode: C. Roddier, F. Roddier, J. E. Graves and M. J. Northcott, Institute for Astronomy, University of Hawaii (UH), report: "Infrared images of Saturn's rings were taken on 1995 Aug. 12 with the UH adaptive-optics system mounted on the Canada-France-Hawaii telescope. After careful processing, evidence was found for a faint streak of light moving away from Saturn at the level of the E ring. The object is elongated in the direction of Saturn with a sharp edge on Saturn's side and a fuzzy tail on the other side. Assuming motion on a keplerian orbit, the object's orbital radius must be within a few km of that of Saturn II (Enceladus). The object's sharp edge is ahead of Enceladus by an orbital longitude of 75 deg. Its orbit is inclined by about 2 deg with respect to the ring plane. The object could possibly be an arc structure confined by gravitational interaction with both Saturn I (Mimas) and Enceladus." Title: Azimuthal distribution of arcs and clumps in the F ring of Saturn during August 1995 ring plane crossing. Authors: Ferrari, C.; Brahic, A.; Charnoz, S.; Thebault, P.; Roddier, F. Bibcode: 1997DPS....29.1703F Altcode: 1997BAAS...29..998F Ground-based observations of the August 1995 Saturn's ring plane crossing with the University of Hawaii Adaptive Optics System have led to the discovery of several new objects orbiting around the planet. Their orbits are known with variable accuracy but most of them are compatible with the F ring. Some of these objects are clearly azimuthally elongated structures, possibly arcs, the others are not resolved. Planetary arcs are swarms of clumps, which largest particles are most probably unresolved kilometer-sized objects (Ferrari and Brahic, 1992, 1994, 1997). Are these objects evolving with time ? On which timescale ? The F ring arcs have been first observed during the Voyager encounters. New constraints on the evolution of the brightest of them, on a two-weeks timescale, at the epoch of the Voyager 2 flyby, are presented. A revised orbit of the F ring is used to derive an azimuthal distribution of the newly discovered objects at August 1995 epoch. This is compared with the azimuthal profile of the F ring observed three months later, during the Sun ring plane crossing (Nicholson et al., 1996). The possible nature and lifetime of these new objects is discussed. Title: Stellar Coronograph with Phase Mask Authors: Roddier, F.; Roddier, C. Bibcode: 1997PASP..109..815R Altcode: The detection of faint light sources very close to a bright star is primarily limited by light scattered by the Earth's atmosphere. This source of scattered light can now be reduced by means of adaptive optics, or totally eliminated by using a telescope in space. Then diffraction by the telescope aperture becomes the primary source of scattered light. Whereas a classical Lyot coronograph can reduce the amount of light diffracted away from the star, it becomes inefficient very close to the star. Instead of forming the stellar image on an opaque mask, it is proposed here to use a small phase plate which produces a 180 degrees phase shift on the core of the stellar image. Light diffracted outside the core is then eliminated by destructive interference. Applied to the Hubble Space Telescope, the technique would easily allow detection of a stellar companion 0.3" away from a star and at least 8 magnitude fainter. (SECTION: Astronomical Instrumentation) Title: Environment of young stars: from adaptive optics to telescope arrays. Authors: Roddier, F. Bibcode: 1997CRASB.325...35R Altcode: Protoplanetary disks around young stars can now be observed with a 0.1″angular resolution using adaptive optics. These observations bring a new vision of the primordial solar nebula. Unfortunately, the close surroundings of the star are masked by its glare. A new stellar coronagraph with a phase mask should enable one to observe much closer to the central star. The technique applies to images produced by telescope arrays. It could allow to detect planets at distances as close as that between the Earth and the Sun. Title: Adaptive optics observations of solar system objects Authors: Roddier, F.; Brahic, A.; Dumas, C.; Graves, J. E.; Han, B.; Northcott, M. J.; Owen, T.; Roddier, C. Bibcode: 1997DPS....29.2701R Altcode: 1997BAAS...29.1023R Diffraction-limited images can now be obtained from the ground using adaptive optics. We present here a number of results obtained with this technique by researchers at the Institute for Astronomy. These include: 1) Observations of the rings of Saturn as the Earth was crossing the ring plane in August 95. Evidence was found for a dozen of 20- to 40-km diameter objects, probably clumps, orbiting at the distance of the F-ring. Among these objects two of them have been identified with objects 1995 S5 and S7 observed by the Hubble Space Telescope. An eclipse of Epimetheus by the F ring was observed, putting new constraints on its orbit as well as the size and density of the F ring. Photometric profiles have been obtained along the rings, and their time evolution has been modeled. 2) Observations of Titan through narrowband filters in and out of the 1.6 micron methane window. The surface feature observed by Smith et al and Combes et al on the leading hemisphere has been detected as well, albeit with morphological differences. A program of adaptive-optics observations of Titan is under way. 3) K-band observations of Uranus and its rings. Puck has been detected. 4) K-band observations of Neptune, confirming that low-latitude cloud activity has shifted from the south to the north hemisphere since Voyager observations. For the first time Proteus was detected from Earth and its albedo was measured at 2.2 mu m. 5) Wide band observations of Pluto and Charon. A program of narrow band photometry of the individual components is under way. 6) Observations of asteroid 4 Vesta during its 1996 opposition through narrow band filters in and out the pyroxene bands. Its dimensions and shape as well as the nature of the geological units present on its surface, have been derived. Title: Adaptive Optics 0.2" Resolution Infrared Images of HL Tauri: Direct Images of an Active Accretion Disk around a Protostar Authors: Close, Laird M.; Roddier, François; J. Northcott, Malcolm; Roddier, Claude; Elon Graves, J. Bibcode: 1997ApJ...478..766C Altcode: We have obtained 0.2" FWHM images of HL Tau at K', H, and J utilizing the University of Hawaii Adaptive Optics System at the 3.6 m CFHT. These are the highest resolution deep images of HL Tau ever obtained in the infrared. They provide unique insight into HL Tau's circumstellar environment. An active accretion disk is directly resolved around HL Tau for the first time in the infrared. The physical characteristics of this accretion disk (RD ~ 150 AU, and P.A. ~ 125°) are consistent with the inner disk discovered by submillimeter (0.8 mm) interferometry by Lay et al. (1994), and confirmed by 2.7 mm interferometry by Mundy et al. (1996).

Bipolar cavities aligned with the accretion disk axis are for the first time detected in the infrared. We have monitored the upper cavity at comparable angular resolution for three epochs over the last 2 yr. The cavity appears to be expanding at up to ~30 km s-1. This cavity is estimated to have been created in an outburst in the direction of the optical jet ~100 yr ago.

Accurate photometry and astrometry were obtained for the nearby 0.3" XZ Tau binary and the unresolved HL Tau star + inner disk at K', H, and for the first time at J. The large H - K = 2.14 +/- 0.11 color of the HL Tau point source indicates an extinction of AJ = 7.73 +/- 0.42 (AV ~ 24) along the line of sight to the star. Based on this large extinction, the SED for HL Tau's unresolved central source was dereddened. A simple accretion disk + star model reproduced the newly dereddened SED. The model assumed a large infalling envelope (as observed in 13CO; see Hayashi et al. 1993) accreting at 5 × 10-6 M⊙ yr-1 onto a stable accretion disk (RD = 150 AU) around a young 0.7 M⊙ pre-main-sequence (PMS) star. We find that to reproduce the observed SED, the central unresolved source in HL Tau is required to be a very young (~105 yr) PMS star surrounded by an active accretion disk. The large observed extinction from the inclined disk implies an estimated accretion disk mass of ~0.04 M⊙. Title: Improved Imaging Performance of the NASA IRTF Telescope Authors: Baron, R. L.; Joseph, R.; Tokunaga, A.; Onaka, P.; Smith, S.; Young, T.; Roddier, F.; Roddier, C.; Hall, D.; Lin, Gang Bibcode: 1997AAS...18912101B Altcode: 1997BAAS...29..733B Improved imaging of the NASA IRTF (Infrared Telescope Facility) is being pursued intensely on a number of fronts. We report initial results, direction for the next steps and current/expected performance. Successful engineering and shared risk observations have been made with a tip-tilt secondary and fast loop control system. Near diffraction limited images (at 2.2 microns and longer wavelengths) with effective exposures of minutes have been taken. Telescope optics are being evaluated and alignment errors minimized using this instrument. The system is still under development and with completion of this work we expect this performance to be available to a large user community. Title: Satellites of Saturn Authors: Roddier, C.; Roddier, F.; Brahic, A.; Graves, J. E.; Northcott, M. J.; Owen, T. Bibcode: 1996IAUC.6515....1R Altcode: C. Roddier and F. Roddier, Institute for Astronomy (IfA), University of Hawaii; A. Brahic, Observatoire de Paris; and J. E. Graves, M. J. Northcott and T. Owen, IfA, report: "Images of Saturn's rings, taken in Aug. 1995 with the University of Hawaii adaptive-optics system mounted on the Canada-France-Hawaii telescope, have now been deconvolved and carefully processed. They show evidence for at least nine additional objects all orbiting in the F ring. A good orbital fit (including the effects of the Saturnian J2 and J4 harmonics) was obtained for all of them with a single distance of 140 500 +/- 500 km. The following list includes the three objects already announced on IAUC 6407. As before, the longitudes (uncertainty +/- 1 deg) are for the epoch 1995 Aug. 10.5 TT (at Saturn) and are measured from the ascending node of Saturn's equator on the earth's J2000.0 equator: S/1995 S 11, longitude 302 deg, estimated radius 12 km; S/1995 S 9, 317, 16; S/1995 S 12, 320, 10; S/1995 S 7 = 1995 S 8, 325, 20; S/1995 S 13, 330, 12; S/1995 S 14, 46, 16; S/1995 S 15, 105, 12; S/1995 S 16, 114, 10; S/1995 S 17, 116, 10; S/1995 S 18, 118, 10; S/1995 S 19, 120, 10; S/1995 S 5 = 1995 S 10, 131, 20. We also find some evidence for S/1995 S 11, S/1995 S 15, S/1995 S 16 and S/1995 S 17 in the HST data (cf. IAUC 6243). S/1995 S 12 is part of the possible S/1995 S 9 arc structure mentioned on IAUC 6407, now resolved into two components; we no longer see evidence for arc structures. The 12 objects listed above cover a total longitude range of 135 deg. Assuming that objects are uniformly distributed, one can estimate that the F ring contains some 32 of them with radii larger than 10 km." Title: First infrared images of the GG Tau ring Authors: Roddier, C.; Roddier, F.; Northcott, M. J.; Graves, J. E. Bibcode: 1996BCFHT..35....9R Altcode: No abstract at ADS Title: Satellites of Saturn Authors: Roddier, F.; Brahic, A.; Dumas, C.; Ferrari, C.; Graves, J. E.; Northcott, M. J.; Owen, T.; Perret, L.; Roddier, C.; Thebault, P. Bibcode: 1996IAUC.6407....1R Altcode: F. Roddier, Institute for Astronomy, University of Hawaii (IfA); A. Brahic, Observatoire de Paris and Universite de Paris (Paris); C. Dumas, IfA; C. Ferrari, Paris; J. E. Graves, M. J. Northcott, and T. Owen, IfA; L. Perret, Paris; C. Roddier, IfA; and P. Thebault, Paris, report: "A new adaptive-optics system developed at the University of Hawaii was operated at the 3.6-m Canada- France-Hawaii telescope during four nights spanning the 1995 Aug. ring-plane crossing. Several hundred 15-, 30-, and 60-s exposures were obtained in the bands I, J, H, and K; the average angular resolution is 0".15 in the H band. Saturn X (Janus), XI (Epimetheus), XII (Helene), XIII (Telesto), XIV (Calypso), XV (Pandora), and XVI (Prometheus) were identified; positions are in fair agreement with the new ephemerides deduced from Hubble Space Telescope (HST) observations. Three additional objects --- S/1995 S 8, S/1995 S 9, and S/1995 S 10 --- have been discovered. The number of fitted observations is given below, followed by our estimate of the equivalent orbital radius and longitude for epoch 1995 Aug. 10.5 TDT (at Saturn), measured from the ascending node of Saturn's equatorial plane on the earth's J2000.0 equator; the fits include the effects of Saturnian J2 and J4 harmonics: S/1995 S 8, 16 observations, 141 400 +/- 1000 km, 323 +/- 1 deg; S/1995 S 9, 16, 141 400 +/- 2000 km, 315 +/- 1.8 deg; S/1995 S 10, 8, 140 050 +/- 100 km, 131.4 +/- 1.1 deg. S/1995 S 10 has been observed on both Aug. 9 and 10; it is co-orbital to the F ring. This object is most probably the candidate satellite S/1995 S 5, which was observed by the HST on Aug. 10. S/1995 S 8 may be identified with S/1995 S 7 observed by HST, since the observations are consistent. The S/1995 S 9 azimuthal extent of 5 deg suggests an arc structure, which may be embedded in the F ring; it cannot be linked with any other objects discovered by HST at the same epoch." Title: Adaptive Optics Imaging of GG Tauri: Optical Detection of the Circumbinary Ring Authors: Roddier, C.; Roddier, F.; Northcott, M. J.; Graves, J. E.; Jim, K. Bibcode: 1996ApJ...463..326R Altcode: High angular resolution images of GG Tau have been obtained in the I, J, H, and K bands with the University of Hawaii adaptive optics system. The close binary pair is found to be near periastron, and it rotates clockwise. It consists of a K7-M0 star with an M4 companion. Masses inferred from dynamical motion are larger than the spectral type suggest. The companion appears to be younger than the main star. Both stars seem to be surrounded with a warm unresolved disk. Images reveal a circumbinary ring also recently detected at millimetric wavelengths. The ring seems to be produced by light scattered by the edge of a cavity inside a much larger disk. At the cavity edge, the disk thickness is estimated to be one-tenth of the cavity radius. Light which illuminates this cavity edge appears to be reddened by absorption through the inner disks. Azimuthal variations of the illumination indicate that the inner disks must be lumpy. Title: Saturn' Rings Edge-on Observations at 0.1 Arcsecond Resolution With Adaptive Optics Authors: Brahic, A.; Dumas, C.; Ferrari, C.; Graves, J.; Han, B.; Northcott, M.; O'Connor, D.; Owen, T.; Perret, L.; Roddier, C.; Roddier, F.; Thebault, P. Bibcode: 1995DPS....27.2709B Altcode: 1995BAAS...27.1132B No abstract at ADS Title: Ground-based Near-Infrared Adaptive-Optics Imaging of the Surface of Titan Authors: Han, B.; Owen, T.; Brahic, A.; Dumas, C.; Roddier, F.; Roddier, C.; Northcott, M.; Graves, J. E.; O'Connor, D. Bibcode: 1995DPS....27.1802H Altcode: 1995BAAS...27.1104H No abstract at ADS Title: Near-Infrared Observations of Pluto and Charon Using Adaptive Optics Imaging Authors: O'Connor, D. J.; Anuskiewicz, J.; Brahic, A.; Dumas, C.; Graves, J. E.; Northcott, M.; Owen, T.; Roddier, C.; Roddier, F. Bibcode: 1995DPS....27.1611O Altcode: 1995BAAS...27.1101O No abstract at ADS Title: Adaptive Optics Imaging of Proto--Planetary Nebulae: Frosty Leo and the Red Rectangle Authors: Roddier, F.; Roddier, C.; Graves, J. E.; Northcott, M. J. Bibcode: 1995ApJ...443..249R Altcode: Near-infrared, 0.1 arcsec resolution images of the bipolar nebulae Frosty Leo and Red Rectangle have been obtained with an adaptive optics system developed at the University of Hawaii. In both cases evidence is found supporting a binary star formation mechanism for the nebulae. Title: First astronomical observations with the University-of-Hawai'i experimental adaptive optics system. Authors: Roddier, F.; Anuskiewicz, J.; Graves, J. E.; Northcott, M. J.; Roddier, C.; Surace, J.; Tokunaga, A. Bibcode: 1995seft.conf..313R Altcode: This paper describes the first scientific results obtained with an experimental adaptive optics system developed at the University of Hawai'i. Observations were made in December 1993 at the 3.6-m Canada-France-Hawai'i Telescope (CFHT), and in January 1994 at the 4-m United Kingdom Infrared Telescope (UKIRT). High angular resolution images of various astronomical sources were obtained in the I band with a CCD camera, and in the J, H and K bands with a 256×256 NICMOS array. In all cases the observed objects were bright enough to serve as a reference source for the wave-front sensor. A brief description of the system and a discussion of its performance are given. The paper describes the observations and the scientific results. Title: Application of interferometry and adaptive optics to the detection of extra-solar planets: a computer simulation. Authors: Roddier, C.; Roddier, F. Bibcode: 1995Ap&SS.223..183R Altcode: No abstract at ADS Title: Prospects for Imaging Interferometry Authors: Roddier, F. Bibcode: 1995Ap&SS.223..109R Altcode: No abstract at ADS Title: Error propagation in a closed-loop adaptive optics system: a comparison between Shack-Hartmann and curvature wave-front sensors. Authors: Roddier, F. Bibcode: 1995OptCo.113..357R Altcode: It is shown that the error propagation problem associated with curvature sensing can be offset when the sensor is used in a closed feedback loop with an unresolved reference point source. A demonstration is given in the ideal case of full compensation under low noise conditions. Title: Testing optical telescopes from defocused stellar images Authors: Roddier, Claude A.; Graves, J. Elon; Northcott, Malcolm J.; Roddier, Francois J. Bibcode: 1994SPIE.2199.1172R Altcode: Wave-front reconstruction from defocused stellar images has now been widely applied to the testing of ground-based optical telescopes. We describe here the latest improvements to the technique and discuss how to reach a maximum accuracy. Statistics are given on the aberrations observed over 10 different telescopes. Title: Adaptive optics at the University of Hawaii IV: a photon-counting curvature wavefront sensor Authors: Graves, J. Elon; Roddier, Francois J.; Northcott, Malcolm J.; Anuskiewicz, Jim; Monnet, Guy Bibcode: 1994SPIE.2201..502G Altcode: A photon counting wavefront curvature sensor (WFS) with 13 subapertures suitable for adaptive optics in astronomy has been developed at the University of Hawaii. This sensor is capable of using very faint point sources or slightly extended sources to derive the wavefront signal. The sensitivity of this sensor is continuously variable and can be adjusted in real time to match the seeing conditions at the time. The wavefront sampling geometry has been optimized for correcting the standard atmosphere up to 9 orders expressed in terms of Zernike's. Its output is used in conjunction with a newly developed deformable bimorph mirror for high efficiency correction capabilities. This WFS has successfully been used recently at the CFHT and UKIRT facilities on Mauna Kea on a variety of astronomical objects. Point sources, double stars, planetary nebula, galactic nuclei, and some of the moons of Jupiter have all been successfully attempted. Limiting magnitude has not been explored in great detail at the telescope, but we have taken the system down to magnitude R equals 13.7 (V equals 15) with a 3.6 meter aperture with success. This was achieved during bright time or whilst the full moon was present. Title: Adaptive optics at the University of Hawaii I: current performance at the telescope Authors: Roddier, Francois J.; Anuskiewicz, Jim; Graves, J. Elon; Northcott, Malcolm J.; Roddier, Claude A. Bibcode: 1994SPIE.2201....2R Altcode: The experimental adaptive optics system, currently developed at the University of Hawaii, is now equipped with a VME-based control system, and a high sensitivity wave-front sensor. The sensor uses an array of 13 photon-counting avalanche photodiodes which enable the system to work with faint reference or `guide' sources, as faint as magnitude 15. Results of the first successful observing runs are described here. Title: Curvature-based wavefront sensor for use on extended patterns Authors: Kupke, Renate; Roddier, Francois J.; Mickey, D. Bibcode: 1994SPIE.2201..519K Altcode: We present results of simulations involving a curvature-based wavefront sensor which uses an extended pattern as a reference source. The proposed sensor provides measurements of both symmetric and asymmetric aberration terms by comparing the Fourier transforms of two oppositely defocused images. Symmetric terms such as defocus and astigmatism can be measured without regard to the object distribution. The asymmetric terms, such as tip and tilt, rely on averaging the signal over many atmospheric realizations in order to determine the object phase, or on defining an arbitrary reference phase. Only after removal of the object Fourier transform phase can the asymmetric terms be identified. Although this paper reports on preliminary results, we believe the proposed sensor will be useful for both real-time compensation of atmospheric distortions while imaging the Sun, and post-facto compensation of optical misalignments in Earth-pointing satellites. Title: The UH Experimental Adaptive Optics System: First Telescope Results with a Photon-Counting Avalanche Photodiode Array Authors: Graves, J. E.; Northcott, M. J.; Roddier, C.; Roddier, F.; Anuskiewicz, J.; Monnet, G.; Rigaut, F.; Madec, P. Y. Bibcode: 1994ESOC...48...47G Altcode: 1994aao..conf...47G No abstract at ADS Title: Adaptive optics: performance and limitations [invited] Authors: Roddier, F. Bibcode: 1994IAUS..158..273R Altcode: No abstract at ADS Title: First Astronomical Observations with the University-of-Hawaii Experimental adaptive optics system Authors: Roddier, F.; Anuskiewicz, J.; Graves, J. E.; Northcott, M. J.; Roddier, C.; Surace, J.; Tokunaga, A. Bibcode: 1994awca.conf...23R Altcode: No abstract at ADS Title: The Problematic of Adaptive Optics Design Authors: Roddier, F. Bibcode: 1994ASIC..423...89R Altcode: 1994aoa..conf...89R No abstract at ADS Title: Prospects in Adaptive Optics for Solar Applications Authors: Roddier, F.; Graves, J. E. Bibcode: 1994IAUS..154..557R Altcode: No abstract at ADS Title: Wave-front reconstruction from defocused images and the testing of ground-based optical telescopes. Authors: Roddier, C.; Roddier, F. Bibcode: 1993JOSAA..10.2277R Altcode: 1993JOSA...10.2277R; 1993OSAJ...10.2277R A new method has been developed for testing the optical quality of ground-based telescopes. Aberrations are estimated from wideband long-exposure defocused stellar images recorded with current astronomical CCD cameras. An iterative algorithm is used that simulates closed-loop wave-front compensation in adaptive optics. Compared with the conventional Hartmann test, the new method is easier to implement, has a similar accuracy, and provides a higher spatial resolution on the reconstructed wave front. It has been applied to several astronomical telescopes and has been found to be a powerful diagnostic tool for improving image quality. Title: SISTERS: a space interferometer for the search for terrestrial exo-planets by rotation shearing Authors: Bely, Pierre Y.; Burrows, Christopher J.; Roddier, Francois J.; Weigelt, Gerd; Bernasconi, M. C. Bibcode: 1993SPIE.1947...73B Altcode: A concept for a space-based interferometer dedicated to the detection of extrasolar earth-like planets is presented. Detection is done in the near infrared (10 micrometers ) where the expected star to planet flux ratio is down to 10(superscript 6) compared to 10(superscript 10) in the visible. The longer wavelength also makes is easier to avoid light scatter due to optics micro-roughness. Parent star cancellation is obtained with a rotation shearing interferometer working at its null on axis. The interferometer is of the Fizeau configuration with an aperture composed of twelve 1.2 meter mirrors on a 20 meter ring. This size, which corresponds to a resolving power of 0.05 arcsecond, allows for the investigation of about 30 candidate stars. The interferometer is supported by a chemically rigidized structure deployed by inflation. All optical elements are passively cooled to about 70 degrees Kelvin to reduce the instrumental infrared background. The spacecraft is located at the second Lagrangian point of the earth-sun system in order to minimize attitude control and baffling requirements. Title: HARDI-2: a high-angular-resolution deployable interferometer for UV observations of nearby stars Authors: Bely, Pierre Y.; Burrows, Christopher J.; Lamers, H. J.; Roddier, Francois J.; Weigelt, Gerd Bibcode: 1993SPIE.1947...84B Altcode: We describe a concept for an orbiting astronomical observatory which will allow high spatial resolution far-UV observations of nearby stars. The scientific goal is to study stellar activity and mass loss using imaging and spectroscopy. Specific areas of study include stellar surfaces, large scale magnetohydroynamic effects, interacting binaries and stellar winds. The instrument is an interferometer with an 8-meter baseline providing 3 milliarcseconds resolution at 1200 Angstrom. The interferometer configuration is of the Fizeau type which affords excellent ultraviolet throughput because of the small number of reflections. The collecting aperture is composed of six 0.6 meter diameter elements distributed on a circle in such a way as lead to near uniform u-v plan coverage when the instrument is rotated around the line of sight. This will lead to excellent imaging capabilities. The interferometer individual channels are kept coaligned and coherent using the light of a nearby guide star. The supporting structure is folded for launch and automatically deployed once on orbit. To minimize disturbance torques and thermal shocks, the spacecraft will be located on a high earth orbit or at the Lagrangian point. Title: Combined approach to the Hubble Space Telescope wave-front distortion analysis. Authors: Roddier, Claude; Roddier, Francois Bibcode: 1993ApOpt..32.2992R Altcode: Stellar images taken by the Hubble Space Telescope at various focus positions have been analyzed to estimate wave-front distortion. Rather than using a single algorithm, the authors found that better results were obtained by combining the advantages of various algorithms. For the planetary camera, the most accurate algorithms consistently gave a spherical aberration of -0.290-μm rms with a maximum deviation of 0.005 μm. Evidence was found that the spherical aberration is essentially produced by the primary mirror. The illumination in the telescope pupil plane was reconstructed and evidence was found for a slight camera misalignment. Title: Testing Telescopes from Out-Of Images - Application to Groundbased Telescopes and to the Space Telescope Authors: Roddier, C.; Roddier, F. Bibcode: 1993oia..conf..236R Altcode: No abstract at ADS Title: SISTERS: a space interferometer for the search for terrestrial exo-planets by rotation shearing. Authors: Bely, P. -Y.; Burrows, C. J.; Roddier, F.; Weigelt, G.; Bernasconi, Marco C. Bibcode: 1992ESASP.354...99B Altcode: 1992tsbi.rept...99B A concept for a space-based interferometer dedicated to the detection of extrasolar earth-like planets is presented. Detection is done in the near infrared (10 μm) where the expected star to planet flux ratio is down to 106 compared to 1010 in the visible. The longer wavelength also makes it easier to avoid light scatter due to optics micro-roughness. Parent star cancellation is obtained with a rotation shearing interferometer working at its null on axis. Title: HARDI: a high angular resolution deployable interferometer. Authors: Bely, P. -Y.; Burrows, C. J.; Roddier, F.; Weigelt, G. Bibcode: 1992ESASP.354..235B Altcode: 1992tsbi.rept..235B The authors describe a proposed orbiting interferometer covering the UV, visible and near-IR spectral ranges. With a 6-meter baseline and a collecting area equivalent to about a 1.4 meter diameter full aperture, this instrument is intended to offer significant improvements in resolution over the Hubble Space Telescope, and complement the new generation of ground-based interferometers with much better limiting magnitude and spectral coverage. Title: HARDI: A high angular resolution deployable interferometer for space Authors: Bely, Pierre Y.; Burrows, Christopher; Roddier, Francois; Weigelt, Gerd Bibcode: 1992NASCP3066..114B Altcode: 1992loui.rept..114B We describe here a proposed orbiting interferometer covering the UV, visible, and near-IR spectral ranges. With a 6-m baseline and a collecting area equivalent to about a 1.4 m diameter full aperture, this instrument will offer significant improvements in resolution over the Hubble Space Telescope, and complement the new generation of ground-based interferometers with much better limiting magnitude and spectral coverage. On the other hand, it has been designed as a considerably less ambitious project (one launch) than other current proposals. We believe that this concept is feasible given current technological capabilities, yet would serve to prove the concepts necessary for the much larger systems that must eventually be flown. The interferometer is of the Fizeau type. It therefore has a much larger field (for guiding) better UV throughout (only 4 surfaces) than phased arrays. Optimize aperture configurations and ideas for the cophasing and coalignment system are presented. The interferometer would be placed in a geosynchronous or sunsynchronous orbit to minimize thermal and mechanical disturbances and to maximize observing efficiency. Title: Status of Astronomical Adaptive Optics Developments Authors: Roddier, F. Bibcode: 1992ESOC...39..571R Altcode: 1992hrii.conf..571R No abstract at ADS Title: Towards lower cost adaptive optics systems. Authors: Roddier, F. Bibcode: 1992aolt.meet...59R Altcode: Techniques to reduce the cost of adaptive optics systems without degrading performance are discussed. Title: Recent results of the UH (University of Hawaii) adaptive optics system. Authors: Graves, J. E.; McKenna, D. L.; Northcott, M. J.; Roddier, F. Bibcode: 1992aolt.meet..146G Altcode: Uncompensated, tip-tilt compensated, and fully compensated images are presented. The compensation is performed in the laboratory, after a seeing generator, and at the telescope. Title: New optical testing methods developed at the University of Hawaii: results on ground-based telescopes and Hubble Space Telescope Authors: Roddier, Claude A.; Roddier, Francois J. Bibcode: 1992SPIE.1531...37R Altcode: New methods have been developed to test telescope optics either at the fabrication stage or while in operation. Results recently obtained at the University of Hawaii are presented. Title: The UH (University of Hawaii) prototype adaptive optics system. Authors: Graves, J. E.; McKenna, D. L.; Northcott, M. J.; Roddier, F. Bibcode: 1992aolt.meet..173G Altcode: A description is given of the adaptive optics system currently built at UH for astronomical applications. Results of laboratory and telescope performance tests are presented. Title: The UH (University of Hawaii) wavefront curvature sensor. Authors: Roddier, F.; Graves, J. E.; McKenna, D. L.; Northcott, M. J. Bibcode: 1992aolt.meet..170R Altcode: The theory of curvature sensing is reviewed and the UH sensor is described. Results of laboratory performance tests are presented. Title: University of Hawaii adaptive optics system: I. General approach Authors: Roddier, F.; Graves, J. E.; McKenna, D.; Northcott, M. Bibcode: 1991SPIE.1542..248R Altcode: An innovative adaptive optics (AO) system is being developed at the University of Hawaii to sharpen images produced by telescopes on Mauna Kea. Title: Reconstruction of the Hubble Space Telescope mirror figure from out-of-focus stellar images Authors: Roddier, C.; Roddier, F. Bibcode: 1991SPIE.1494...78R Altcode: From the illumination recorded in two defocused stellar images it is possible to reconstruct both the amplitude and the phase of the incoming wave front viewed from the focal plane, providing a powerful diagnostic tool for telescope optics. Results obtained from defocused stellar images taken in flight by the Hubble Space Telescope are presented. Title: Large-mirror testing facility at the National Optical Astronomy Observatories. Authors: Barr, L. D.; Coudé du Foresto, V.; Fox, J.; Poczulp, G. A.; Richardson, J.; Roddier, C.; Roddier, F. Bibcode: 1991OptEn..30.1405B Altcode: A method for testing the surfaces of large mirrors has been developed to be used even when conditions of vibration and thermal turbulence in the light path cannot be eliminated. The full aperture of the mirror under test is examined by means of a scatterplate interferometer that has the property of being a quasi-common-path method, although any means for obtaining interference fringes will do. The method uses a remotely operated CCD camera system to record the fringe pattern from the workpiece. The typical test is done with a camera exposure of about a millisecond to "freeze" the fringe pattern on the detector. Averaging up to 10 separate exposures effectively eliminates the turbulence effects. The method described provides the optician with complete numerical information and visual plots for the surface under test and the diffracted image the method will produce, all within a few minutes, to an accuracy of 0.01 μm measured peak-to-valley. Title: Large-mirror testing facility at the National Optical Astronomy Observatories Authors: Coudé du Foresto, V.; Fox, J.; Poczulp, G. A.; Richardson, J.; Roddier, Claude; Roddier, Francois; Barr, L. D. Bibcode: 1991OptEn..30.1405C Altcode: A method for testing the surfaces of large mirrors has been developed to be used even when conditions of vibration and thermal turbulence in the light path cannot be eliminated. The full aperture of the mirror under test is examined by means of a scatterplate interferometer that has the property of being a quasi-common-path method, although any means for obtaining interference fringes can be used. By operating the test equipment remotely, the optician does not cause unnecessary vibrations or heat in the testing area. The typical test is done with a camera exposure of about a millisecond to 'freeze' the fringe pattern on the detector. Averaging up to 10 separate exposures effectively eliminates the turbulence effects. From the intensity information, a phase map of the wavefront reflected from the surface is obtained using a phase-unwrapping technique. The method provides the optician with complete numerical information and visual plots for the surface under test and the diffracted image the method will produce to an accuracy of 0.01 micron measured peak-to-valley. The method has been extensively used for a variety of test of a 1.8-m-diam borosilicate-glass honeycomb mirror, where the method was shown to have a sensitivity equal to a Foucault test. Title: A Simple Low-Order Adaptive Optics System for Near-Infrared Applications Authors: Roddier, Francois; Northcott, Malcolm; Graves, J. Elon Bibcode: 1991PASP..103..131R Altcode: It is shown that low-order wavefront compensation can significantly improve astronomical images over most of the sky. A novel approach to wavefront sensing and compensation is described. It is optimized for low-order correction and high efficiency. Computer-simulation results show it can achieve the desired performance, and preliminary laboratory tests demonstrate its feasibility. Title: Self-calibration in rotational shearing interferometry Authors: Roddier, Claude; Roddier, Francois Bibcode: 1990SPIE.1351..698R Altcode: Diffraction-limited imaging of an incoherent object observed through fixed unknown aberrations is demonstrated using rotational shear interferograms. Reconstruction algorithms were inspired by radio-astronomy self-calibration methods. They require no reference point source other than the object itself to calibrate the effects of aberrations. Title: Variations on a Hartmann theme. Authors: Roddier, F. Bibcode: 1990OptEn..29.1239R Altcode: The author explores modifications of the classical Hartmann wavefront sensing technique that can be used to improve its accuracy, dynamic range, and spatial resolution. He describes a differential sensor with variable sensitivity. The author reviews the use of various possible Hartmann masks and discusses their interferometric properties. He propose the use of Fourier analysis and shows its relationship to moire methods. The author finally envisages the possibility of mapping both the slope and the total curvature (Laplacian) of the wavefront with the same setup. Title: Diffraction-limited imaging of unknown objects through fixed unknown aberrations using interferometry. Authors: Roddier, Claude; Roddier, Francois Bibcode: 1990JOSAA...7.1824R Altcode: 1990OSAJ....7.1824R; 1990JOSA....7.1824R Diffraction-limited imaging of unknown objects through fixed unknown aberrations is demonstrated using rotational shear interferograms. Objects are assumed to be fully incoherent. No reference point source is used to calibrate the effects of aberrations. Several algorithms are described, and two are successfully used to reconstruct extended objects. Best results are obtained by combining the two successful ones. Title: Spatial interferometry in optical astronomy. Authors: Gezari, Daniel Y.; Roddier, Francois; Roddier, Claude Bibcode: 1990sioa.book.....G Altcode: This report is a bibliographic guide to publications of spatial interferometry techniques applied to optical astronomy. Listings appear in alphabetical order, by first author, as well as in specific subject categories listed in chronological order, including imaging theory and speckle interferometry, experimental techniques, and observational results of astronomical studies of stars, the Sun, and the solar system. Title: Variations on a Hartmann theme Authors: Roddier, Francois J. Bibcode: 1990SPIE.1237..662R Altcode: No abstract at ADS Title: A space interferometer concept for the detection of extrasolar earth-like planets. Authors: Bely, P. Y.; Burrows, C. J.; Roddier, F. Bibcode: 1990SPIE.1237..198B Altcode: A concept for a space-based interferometer dedicated to the detection of extrasolar earth-like planets is described. The interferometer is of the Fizeau configuration with an aperture composed of twelve 1.2 m mirrors on a 20 m ring. The subapertures are distributed to optimize the u-v plane coverage when the interferometer is rotated around its axis. Parent star cancellation is obtained by the combination of a coronagraph and a rotation shearing interferometer. The interferometer is supported by a chemically rigidized structure deployed by inflation. Due to the lack of side shield and the resulting limited pointing capability with respect to the sun, it is proposed to locate the instrument at the second Lagrangian point of the earth-sun system. Title: Testing of telescope optics: a new approach Authors: Roddier, C.; Roddier, F.; Stockton, A.; Pickles, A.; Roddier, N. Bibcode: 1990SPIE.1236..756R Altcode: Results recently obtained for the use of the curvature-sensing method as a substitute for slope sensing in optical wavefront reconstruction, using long-exposure CCD images of the beam cross-section on either side of the telescope focal plane. A program based on the solution to the Poisson equation is then applied in order to reconstruct the wavefront. Relative to the existing Hartmann sensing methods, curvature-sensing yields sensitivity comparable to that of the Shack-Hartmann test. Additional optics and reference plane-based calibration are obviated. Tests of the new method on an 88-inch Ritchey-Chretien telescope have yielded a map of residual wavefront errors as a solution of the Poisson equation. Title: Seeing monitor based on wavefront curvature sensing Authors: Roddier, F.; Graves, J. E.; Limburg, E. Bibcode: 1990SPIE.1236..474R Altcode: A new wavefront sensing technique called curvature sensing is described. It maps the wavefront total curvature rather than its slope and has been applied to an experimental seeing monitor which detects turbulence induced fast focus fluctuations. Some of the advantages this monitor presents, as compared to DIMM's, are: (1) sensitivity is increased by the use of a circular pupil, (2) the cost is lowered by the use of a photomultiplier, (3) the loss of signal is prevented by the system's fast run, (4) the system runs continuously, and (5) the noise bias is continuously measured and subtracted out. Title: Seeing at Mauna Kea: a joint UH-UN-NOAO-CFHT study Authors: Roddier, Francois J.; Cowie, L. L.; Graves, J. Elon; Songaila, A.; McKenna, Daniel; Vernin, Jean; Azouit, M.; Caccia, J. L.; Limburg, Eric J.; Roddier, Claude A.; Salmon, Derrick A.; Beland, Stephane; Cowley, David J.; Hill, S. Bibcode: 1990SPIE.1236..485R Altcode: Two short-term campaigns are described in which several instruments were simultaneously used to obtain quantitative estimates of the various contributions to image degradation at the Mauna Kea observatory. The various contributions include the free atmosphere, boundary layer turbulence, dome and mirror seeing effects, and telescope optics. A secondary goal of the study was to investigate the relationship between seeing and meteorological conditions on Mauna Kea, which may lead to seeing forecasting. The first campaign was held from November 1 to 13, 1987; the second was held from June 9 to 19, 1989. The campaigns were a cooperative effort involving five institutions: the Institute of Astronomy and the Department of Meteorology both at the University of Hawaii (UH), the National Optical Astronomy Observatories (NOAO) in Tucson, the Canada-france-Hawaii Corporation (CFHT), and the Department of Astrophysics at the University of Nice (UN), France. The general approach, instruments used, and some of the results already obtained are described. Title: Bibliography of spatial interferometry in optical astronomy Authors: Gezari, Daniel Y.; Roddier, Francois; Roddier, Claude Bibcode: 1990STIN...9020911G Altcode: The Bibliography of Spatial Interferometry in Optical Astronomy is a guide to the published literature in applications of spatial interferometry techniques to astronomical observations, theory and instrumentation at visible and infrared wavelengths. The key words spatial and optical define the scope of this discipline, distinguishing it from spatial interferometry at radio wavelengths, interferometry in the frequency domain applied to spectroscopy, or more general electro-optics theoretical and laboratory research. The main bibliography is a listing of all technical articles published in the international scientific literature and presented at the major international meetings and workshops attended by the spatial interferometry community. Section B summarizes publications dealing with the basic theoretical concepts and algorithms proposed and applied to optical spatial interferometry and imaging through a turbulent atmosphere. The section on experimental techniques is divided into twelve categories, representing the most clearly identified major areas of experimental research work. Section D, Observations, identifies publications dealing specifically with observations of astronomical sources, in which optical spatial interferometry techniques have been applied. Title: The ESO differential image motion monitor Authors: Sarazin, M.; Roddier, F. Bibcode: 1990A&A...227..294S Altcode: This paper describes the ESO differential image-motion monitor and reviews the theory of differential image motion measurements. It is shown that this small transportable image-motion monitor, which is able to operate in the open air, can yield quantitative estimates of the image quality produced by a large telescope situated at the same location. Several copies of this instrument are being used for the European Very Large Telescope site testing campaign, in search of the best possible location for this telescope. Title: Active telescope systems Authors: Roddier, Francois J. Bibcode: 1989SPIE.1114.....R Altcode: The present conference discusses topics in the fundamental limitations of adaptive optics in astronomical telescopy, integrated telescope systems designs, novel components for adaptive telescopes, active interferometry, flexible-mirror and segmented-mirror telescopes, and various aspects of the NASA Precision Segmented Reflectors Program. Attention is given to near-ground atmospheric turbulence effects, a near-IR astronomical adaptive optics system, a simplified wavefront sensor for adaptive mirror control, excimer laser guide star techniques for adaptive astronomical imaging, active systems in long-baseline interferometry, mirror figure control primitives for a 10-m primary mirror, and closed-loop active optics for large flexible mirrors subject to wind buffet deformations. Also discussed are active pupil geometry control for a phased-array telescope, extremely lightweight space telescope mirrors, segmented-mirror manufacturing tolerances, and composite deformable mirror design. Title: HARDI: a high angular resolution deployable interferometer for space Authors: Bely, Pierre Y.; Burrows, Christopher; Roddier, Francois; Weigelt, Gerd Bibcode: 1989SPIE.1130...92B Altcode: The present orbiting interferometer proposal for operation in the UV, visible, and near-IR spectral ranges employs a 6-m baseline and a collecting area equivalent to an approximately 1.4-m diameter aperture. The instrument, which is of Fizeau type and therefore possesses better UV throughput than phased arrays, is projected to be able to furnish resolutions superior to those of the Hubble Space Telescope, as well as to complement prospective ground-based interferometers with its greater limiting magnitude and spectral coverage. A single launch will suffice to place the system in GEO or sun-synchronous orbit, in order to minimize thermal and mechanical disturbances and maximize observing efficiency. Title: Curvature sensing and compensation: a computer simulation. Authors: Roddier, Nicolas; Roddier, Francois Bibcode: 1989SPIE.1114...92R Altcode: The concept of curvature sensing and compensation in adaptive optics is investigated by means of a computer simulation. Satisfactory correction is observed when the signal from a 13 element sensor is directly applied to a simulated membrane mirror. Title: Diffraction-limited imaging through aberrated optics using pupil-plane and/or image-plane information Authors: Roddier, Francois; Roddier, Claude; van Peursem, Stacy Bibcode: 1989SPIE.1059..173R Altcode: Diffraction-limited imaging of an unknown, incoherently illuminated object is demonstrated through strongly aberrated optics with unknown aberrations. No reference source other than the object itself is used to calibrate the aberrations. Two different techniques are discussed and their merits are compared. Title: Optical Propagation and Image Formation Through the Turbulent Atmosphere Authors: Roddier, F. Bibcode: 1989ASIC..274...33R Altcode: 1989dli..conf...33R No abstract at ADS Title: Pupil-Plane Interferometry Authors: Roddier, C.; Roddier, F. Bibcode: 1989ASIC..274..221R Altcode: 1989dli..conf..221R No abstract at ADS Title: Diffraction-limited imaging through aberrated optics using pupil-plane and/or image-plane information. Authors: Roddier, F.; Roddier, C.; van Peursem, S. Bibcode: 1989sscn.conf..173R Altcode: Diffraction-limited imaging of an unknown, incoherently illuminated object is demonstrated through strongly aberrated optics with unknown aberrations. No reference source other than the object itself is used to calibrate the aberrations. Two different techniques are discussed and their merits are compared. Title: Spatially resolving the stellar environment. Authors: Roddier, Francois Bibcode: 1989mse..proc...65R Altcode: High angular resolution stellar interferometry at optical wavelengths is making rapid progress. This contribution reviews the techniques of speckle interferometry and speckle imaging, pupil-plane interferometry, adaptive optics, and long-baseline optical interferometry. Within a decade or two, imaging stars and their environment will be possible with telescope arrays in space and on the ground. Title: Compact rotational shearing interferometer for astronomical applications. Authors: Roddier, C.; Roddier, F.; Demarcq, J. Bibcode: 1989OptEn..28...66R Altcode: The fabrication and assembly of a compact rotational shearing interferometer with variable shear and phase compensation is described. The interferometer has been used for seeing measurements and interferometric imaging in optical astronomy. Title: Interferometric imaging in optical astronomy Authors: Roddier, F. Bibcode: 1988PhR...170...97R Altcode: Not Available

Operated by the Association of Universities for Research in Astronomy, Inc., under contract with the National Science Foundation. Title: Diffraction-limited astronomical infrared imaging through the turbulent atmosphere Authors: Christou, J. C.; Freeman, J. D.; McCarthy, D. W., Jr.; Roddier, F.; Beckers, J. M. Bibcode: 1988JPhD...21S..49C Altcode: No abstract at ADS Title: Curvature Sensing and Compensation: A New Concept in Adaptive Optics Authors: Roddier, F.; Roddier, C. Bibcode: 1988ESOC...30..667R Altcode: 1988vltt.conf..667R; 1988vlti....2..667R The authors describe a new wavefront sensor which can favourably replace the Shack-Hartmann sensor either for the control of telescope optics or in adaptive optics systems. In the last case the sensor delivers a signal which can be directly applied to a membrane mirror producing a very simple and fast, entirely analog, control loop. Title: Coupling starlight into single-mode fiber optics Authors: Shaklan, Stuart; Roddier, Francois Bibcode: 1988ApOpt..27.2334S Altcode: The efficiency with which starlight can be coupled into a single-mode fiber optic that is placed in the focal plane of a telescope has been calculated. The calculations are performed for a wide range of seeing conditions, with and without rapid image stabilization, and for a wide range of wavelengths. The dependence of coupling efficiency on the f-ratio of the incident beam is explored. Also, the coupling efficiency as a function of displacement for a perfect Airy pattern is calculated. A computer program is used which simulates atmospheric wavefronts to determine the variance of instantaneous coupling efficiency as a function of seeing. In perfect conditions, the maximum efficiency at the LP11 mode cutoff is 78 percent due to the mismatch of the Airy pattern and the nearly Gaussian mode of the fiber. Maximum total coupled power is attained at d/r(0) = 4 with rapid image stabilization. Title: Curvature sensing and compensation: a new concept in adaptive optics Authors: Roddier, François Bibcode: 1988ApOpt..27.1223R Altcode: No abstract at ADS Title: Application of bispectrum analysis for phase recovery from one-dimensional infrared speckle data. Authors: Freeman, J. D.; Christou, J. C.; Roddier, F.; McCarthy, D. W., Jr.; Cobb, M. L. Bibcode: 1988JOSAA...5..406F Altcode: 1988OSAJ....5..406F The authors apply bispectrum analysis to one-dimensional astronomical infrared specklegrams and compare the recovered phases and their variances with those obtained by the Knox-Thompson algorithm. A number of averaging techniques are used to combine the multiple object phase estimates from the average bispectrum phases. Analysis of these techniques indicates that only a fraction of the nonredundant support of the bispectrum is necessary for the object phase retrieval. The authors have calibrated their bispectra for zero-mean additive detector noise. Results are presented for a bright point source and the nearby binary star Ross 614AB along with its point-source comparison. Title: An Entry Level Interferometer for Space Authors: Bely, P. Y.; Burrows, C.; Roddier, F.; Weigelt, G. Bibcode: 1988soae.conf....6B Altcode: No abstract at ADS Title: Passive versus active methods in optical interferometry. Authors: Roddier, F. Bibcode: 1988ESOC...29..565R Altcode: 1988hrii.conf..565R This paper is an attempt to compare active versus passive methods for image reconstruction. Adaptive optics is shown to provide a better signal-to-noise ratio on bright sources whereas passive image reconstruction is more effective on faint sources. The same two kinds of approach and the same conclusion also apply to long baseline interferometry and image reconstruction from aperture synthesis. Concepts developed for adaptive optics can be applied with profit to telescope arrays. In this case, the active approach seems more practical. Title: Pupil Plane Interferometry Authors: Roddier, C.; Roddier, F. Bibcode: 1988dli..conf..221R Altcode: No abstract at ADS Title: Optical Propagation and Image Formation Through the Turbulent Atmosphere Authors: Roddier, F. Bibcode: 1988dli..conf...33R Altcode: No abstract at ADS Title: Phase recovery from pupil-plane interferograms. Authors: Roddier, C.; Roddier, F. Bibcode: 1988ESOC...29..257R Altcode: 1988hrii.conf..257R No abstract at ADS Title: Application of speckle masking to 1-D infrared speckle data: modulus recovery and imaging. Authors: Christou, J. C.; Freeman, J. D.; McCarthy, D. W., Jr.; Roddier, F. Bibcode: 1988ESOC...29..201C Altcode: 1988hrii.conf..201C The authors have applied the speckle masking or bispectrum algorithm to both real and simulated 1-D infrared speckle data in order to retrieve the phase information. The bispectrum modulus has also been used as an alternative approach to obtain the Fourier modulus of the data. The authors show results, including images, from real data obtained using slit scanning data as well as the NOAO infrared speckle camera. Title: Interferometric imaging in optical astronomy. Authors: Roddier, F. Bibcode: 1988PhR...170...99R Altcode: No abstract at ADS Title: Phase variances from triple correlation analysis Authors: Roddier, Francois; Christou, Julian C. Bibcode: 1988OptCo..65..115R Altcode: A simple heuristic model for the triple correlation procedure (Roddier, 1986) is extended to enable computation of the variances of bispectrum phases. The bispectrum analysis is applied to one-dimensional infrared speckle data obtained at the 2.3-m Stewart Observatory telescope for an unresolved source, validating the effectiveness of the method. Good qualitative agreement is also obtained between the measured and model bispectrum SNR. It is noted that the recovered phases of HR 1739 show structure that is not commensurate with a point source. Title: Fiber linked telescope arrays on the ground and in space Authors: Connes, P.; Roddier, F.; Shaklan, S.; Ribak, E. Bibcode: 1987ESASP.273...73C Altcode: 1987ois..work...73C The use of single-mode optical fibers in telescope arrays, first proposed for a set of free-flying spacecraft, is developed and applied to more modest, shorter range projects. The basic advantage remains a considerable simplification in the control system; the main limitation is spectral range. Two proposals are described: a ground-based array of small optical telescopes supported on a radio dish, and a similar space array. The control system is almost the same in both cases, hence the ground-based array can be considered a test-bench for the space device. Title: Imaging strategies for a space-borne interferometer Authors: Roddier, Francois Bibcode: 1987ESASP.273...23R Altcode: 1987ois..work...23R The author describes two main strategies: (1) a large filled aperture consisting of a mosaic of light-weight mirrors. Internal referencing is used to coalign and approximately cophase the array. Diffraction-limited imaging is achieved by means of interferometric techniques such as roll deconvolution or pupil-plane interferometry. (2) A diluted array of diffraction-limited telescopes. Such an array can be exactly coaligned and cophased using internal and/or external references. In case of either strategy, pointing accuracy and mechanical vibrations will limit the system performances. Title: Single-mode fiber optics in a long-baseline interferometer Authors: Shaklan, Stuart B.; Roddier, Francois Bibcode: 1987ApOpt..26.2159S Altcode: The potential for using single-mode fiber optics to link two or more telescopes in a large optical to near-IR astronomical interferometer was investigated. On an optical bench, the effects of dispersion, temperature, and birefringence on wide-bandwidth interference fringes were observed using up to 30 m of single-mode fiber in each arm of a Twyman-Green interferometer. Title: Application of Bispectrum Analysis to 1-D Infrared Speckle Data Authors: Christou, J. C.; Freeman, J. D.; Roddier, F.; McCarthy, D. W.; Cobb, M. L. Bibcode: 1987BAAS...19..749C Altcode: No abstract at ADS Title: The physics of seeing: application of theory to site evaluation and testing. Authors: Roddier, F. Bibcode: 1987iopo.conf...12R Altcode: Theory is used as a guideline to find an optimum strategy for the evaluation of seeing quality. The ESO experimental campaign is described as an example. Title: The Alpha-Orionis Envelope and its Evolution Authors: Roddier, C.; Roddier, F. Bibcode: 1987iia..conf..231R Altcode: No abstract at ADS Title: Ground-based interferometry. Authors: Roddier, F. Bibcode: 1987txra.symp...41R Altcode: The results of high-angular-resolution interferometric observations are reviewed, and prospects of future developments with ground-based telescopes are discussed. Stellar sources up to magnitude m = 16 have been resolved at the diffraction limit of large telescopes. Complete image reconstruction of turbulence-degraded images is now currently achieved, and new promising techniques are being developed for this purpose. Submarcsec resolution has been achieved with long-baseline interferometers using intensity interferometry, and marcsec resolution is now achieved with much higher sensitivity using direct Michelson interferometry. Title: Application of Triple Correlation to One-Dimensional Infrared Speckle Data Authors: Freeman, J. D.; Christou, J. C.; Roddier, F.; McCarthy, D. W., Jr.; Cobb, M. L. Bibcode: 1987iia..conf...47F Altcode: Triple correlation analysis, also known as bispectrum or speckle masking, is a recently introduced technique to recover object phases from atmospherically degraded short-exposure images (specklegrams). In this paper the authors discuss how they have applied the bispectrum analysis to 1-D infrared speckle data, taking into account additive detector noise, to obtain object phases and to compare these phases to those obtained using Knox-Thompson analysis. The authors also compare three methods of obtaining the object phases from the bispectrum phases, one of which is a rigorous statistical analysis using a minimum variance unbiased estimator. Title: Application of bispectrum analysis to infrared speckle data. Authors: Christou, J. C.; Freeman, J. D.; Roddier, F.; McCarthy, D. W., Jr.; Cobb, M. L.; Shaklan, S. B. Bibcode: 1987SPIE..828...32C Altcode: The bispectrum algorithm is applied to one-dimensional infrared speckle data for retrieval of diffraction-limited phases using a standard weighting-averaging technique to combine the multiple phase estimates contained in the bispectrum. The bispectrum modulus is also used to obtain visibility amplitudes. Results, including images, are presented for three different binary stars. Simulated data have also been used to study the behavior of the algorithm under different signal-to-noise conditions, as well as a study of phase recovery for different defocus conditions. The algorithm is sensitive, at a low level, to focus changes, especially for noisy data. Comparison of the bispectrum phases is made with those obtained from Knox- Thompson cross spectra for all cases. Title: Processing of Interferograms Authors: Roddier, C.; Roddier, F. Bibcode: 1987iia..conf...25R Altcode: Since 1976, the authors have developed algorithms to map both the amplitude and the phase of the fringes in pupil-plane interferograms. These algorithms are essentially based on fast Fourier transforms. The authors describe here the latest improvements. Title: Choix du site. Authors: Roddier, F. Bibcode: 1987JAF....29...31R Altcode: No abstract at ADS Title: Seeing and atmospheric turbulence: parameters relevant to adaptive optics. Authors: Roddier, F. Bibcode: 1987LFTR...28....7R Altcode: Atmospheric parameters relevant to adaptive optics are reviewed and the fundamental limitations imposed by the atmosphere are discussed. Title: Image reconstruction from rotational shear interferograms: laboratoryand astronomical results. Authors: Roddier, Francois; Roddier, Claude Bibcode: 1987SPIE..828..108R Altcode: Images can be reconstructed from incoherent holograms recorded with a rotation shearing interferometer. Reconstruction is possible through strong optical aberrations if holograms are also taken either of a reference source through the same shear, or of the same source through a different shear. Title: Curvature sensing and compensation. Authors: Roddier, F.; Forbes, F.; Shaklan, S.; Pinches, C. Bibcode: 1987LFTR...28..169R Altcode: A new concept is proposed for real-time sensing and compensation of atmospherically distorted wavefronts, using natural (incoherent), possibly extended, reference sources. Instead of measuring an array of 2-dimensional tilts, the optical sensor is sensitive to the local wavefront curvature and to radial tilts at the pupil edge. Radial tilts provide the boundary conditions required to solve the Poisson equation for the wavefront. The sensor delivers a signal which can be amplified and directly applied as a potential distribution on a bimorph or a membrane mirror without requiring any computation. Title: High angular resolution infrared imaging at NOAO (Poster) Authors: Christou, J. C.; Beckers, J. M.; Roddier, F.; Ridgway, S.; Probst, R.; Freeman, J. D.; McCarthy, D. W., Jr.; Cobb, M. L. Bibcode: 1987iawa.conf..464C Altcode: The authors discuss how the SBRC 58×62 InSb infrared imaging array will be used for 2-D infrared speckle interferometry (IRSI) at NOAO. The 2-D IRSI is a logical extension of the 1-D slit-scanning technique currently employed by a number of groups. Title: Signal-To Ratios and Beam Combination Authors: Roddier, F. Bibcode: 1987iia..conf..135R Altcode: No abstract at ADS Title: Phase Closure with Rotational Shear Interferometers Authors: Roddier, F.; Roddier, C. Bibcode: 1987iia..conf...79R Altcode: The authors show that phase closure relations can be obtained from rotational shear interferograms and they discuss the necessary conditions for the object phases to be recovered from such relations. Title: Redundant versus nonredundant beam recombination in an aperture synthesis with coherent optical arrays. Authors: Roddier, F. Bibcode: 1987JOSAA...4.1396R Altcode: 1987OSAJ....4.1396R Signal-to-noise ratios for the amplitude of the object Fourier components are compared assuming either redundant or nonredundant beam recombination. A general condition is given for the object brightness below which redundant beam recombination is superior. A similar condition is found when the variance of the closure phases is considered. Title: Seeing measurements with a pupil-plane rotation shearing interferometer. Authors: Roddier, C.; Roddier, F. Bibcode: 1987iopo.conf...77R Altcode: A compact, very stable, rotation-shearing interferometer is used to determine seeing quality from wavefront coherence measurements on the telescope pupil. A change in the rotational shear enables optimization of the instrument according to telescope size and seeing conditions. Fringes are recorded directly on film without intensification. Fried's seeing parameter r0 is estimated with a few per cent accuracy. The result of recent measurements is presented. Title: A Fiber-Linked Groundbased Array Authors: Connes, P.; Shaklan, S.; Roddier, F. Bibcode: 1987iia..conf..165C Altcode: The authors give a preliminary discussion of what a multi-telescope fiber-linked ground-based array might look like, and an account of some encouraging fiber tests performed at NOAO. Title: Single Aperture Interferometry - General Introduction Authors: Roddier, F. Bibcode: 1987iia..conf....1R Altcode: The paper deals with interferometric techniques used to reconstructed turbulence degraded images through a single telescope. The author reviews the physical basis of these techniques and describes briefly the present state of the art without trying to be exhaustive. Title: Imaging stellar structures and surfaces. Authors: Roddier, Francois Bibcode: 1987LIACo..27..247R Altcode: 1987oahp.proc..247R After having reviewed the basis of maximum entropy methods, the author reviews several techniques which have been used to produce stellar images starting from the most indirect ones. In the most direct ones, interferometric techniques, the spatial coherence of the light is measured and used to produce images almost as in a direct imaging process. With the development of long baseline interferometry at optical wavelengths, these techniques are likely to produce considerable advances in the field of stellar physics. Title: Pupil plane versus image plane in Michelson stellar interferometry. Authors: Roddier, Francois Bibcode: 1986JOSAA...3.2160R Altcode: 1986OSAJ....3.2160R Photon noise statistics are used to estimate the effect of image motion or guiding errors on the signal-to-noise ratio for the fringe visibility either in pupil-plane or in image-plane measurements. Pupil-plane observations are found to provide better results in all cases. Title: Phase closure with rotational shear interferometers. Authors: Roddier, Francois; Roddier, Claude Bibcode: 1986OptCo..60..350R Altcode: Two rotational shear interferometers, with the shear angle of one being twice that of the other, are employed to obtain phase closure relations and to make possible the complete reconstruction of an incoherent object through unknown aberrations. Complete image reconstruction is possible with a single exposure in which two interferograms are recorded simultaneously, and the present method is very efficient on bright sources, though reconstruction on faint sources is possible by averaging closure phasors over many exposures. It is noted that multiple path integration would require many more phase closure relations, and more than two interferometers. Title: Triple correlation as a phase closure technique Authors: Roddier, François Bibcode: 1986OptCo..60..145R Altcode: A simple heuristic model is used to discuss the relationship between triple correlation and phase closure in interferometric image reconstruction. The main properties of triple correlation are easily rederived giving deeper insight into the method.

Operated by the Association of Universities for Research in Astronomy, Inc., under contract with the National Science Foundation. Title: High Resolution Mirror Figure Estimates from Interferograms Authors: Roddier, C.; Roddier, F.; Richardson, J. Bibcode: 1986BAAS...18..944R Altcode: No abstract at ADS Title: New Observations of Alpha Orionis with a Rotation Shearing Interferometer Authors: Roddier, F.; Roddier, C.; Petrov, R.; Martin, F.; Ricort, G.; Aime, C. Bibcode: 1986ApJ...305L..77R Altcode: New two-dimensional maps of the visibility of fringes produced by Alpha Orionis have been obtained at several wavelengths using the McMath telescope at Kitt Peak in 1982 February. These maps show evidence for a time evolution of the dust envelope and indicate a possible stellar companion. Comparison with more recent speckle data favors our interpretation. Title: Betelgeuse Correction Authors: Roddier, F. Bibcode: 1986S&T....71..541R Altcode: No abstract at ADS Title: Signal-to-noise ratio in differential speckle interferometry. Authors: Petrov, R.; Roddier, F.; Aime, C. Bibcode: 1986JOSAA...3..634P Altcode: 1986OSAJ....3..634P Expressions are given for the signal-to-noise ratio of the amplitude and for the uncertainty of the phase of the cross spectrum of two speckle images in the presence of photon shot noise. Applications to astronomical observations are discussed. Title: Use of single-mode fibers in an optical interferometric array. Authors: Shaklan, S.; Roddier, F. Bibcode: 1986JOSAA...3P...5S Altcode: 1986OSAJ....3....5S No abstract at ADS Title: Interferometric seeing measurements at La Silla. Authors: Roddier, Claude; Roddier, Francois Bibcode: 1986ESOC...24..269R Altcode: 1986vlt..work..269R The transfer function for long-exposure astronomical images is the product of the telescope transfer function and the wavefront coherence function. Since coherence is best measured interferometrically, interferometers appear to be the most appropriate tools to make accurate estimates of seeing quality, independent of the optical performance of the telescope. In 1975, C. Roddier used a rotational shear interferometer, optimizing the instrument efficiency by adjusting the angular shear to telescope size and seeing conditions. The increase in sensitivity was so large that it became possible to record fringes directly on Tri-X film without intensification. The instrument was later used simultaneously with a scidar to estimate the relative contribution of upper and lower layers in the atmosphere. The authors describe similar measurements made at La Silla during the February 1986 site testing campaign. Title: National Optical Astronomy Observatories (NOAO) IR adaptive optics program. III - Criteria for the wavefront sensor selection Authors: Goad, L.; Roddier, F.; Beckers, J.; Eisenhardt, P. Bibcode: 1986SPIE..628..305G Altcode: The NOAO IR Adaptive Optics Program has elected to develop a system using the visual light from an object to sense the wavefront errors and generate the corrections required to give diffraction-limited imaging in the near-IR (2-10 microns). The performance of a variety of possible sensors systems has been evaluated, computing both their ideal performance and their expected performance with available detectors. A major consideration in this evaluation is the ability of the sensor to measure mean wavefront tilts of the visual wavefront over subapertures corresponding to the (larger) IR wavefront scale lengths. A Hartmann-Shack sensor with red-sensitive image intensifiers and a Reticon detector are used. Title: Guidelines for a site testing campaign and the LASSCA (La Silla Site Campaign) experience. Authors: Roddier, F. Bibcode: 1986ESOC...24..261R Altcode: 1986vlt..work..261R The application of state-of-the-art measurement techniques to the evaluation of astronomical observatory sites is discussed, and the methods used in the La Silla Site Campaign (LASSCA) to characterize a prospective site for the ESO Very Large Telescope are described. The limitations of conventional site assessments based on observations through a moderate-size telescope are indicated; the effects of atmospheric properties, refractive-index properties, and wavefront properties on image properties are examined theoretically; and the value of newly available wavefront measurements and remote-sensing data on turbulence is stressed. LASSCA comprised seeing-disk profiles and speckle interferograms, rotation shearing interferograms and differential image-motion measurements, tower microthermal measurements and acoustic soundings, scidar (Vernin and Pelon, 1985) turbulence soundings, soil-temperature measurements, and tower and balloon data on temperature and winds. Title: Concepts for a large telescope in space with interferometric imaging Authors: Bely, P. Y.; Roddier, F. Bibcode: 1986aiaa.meetQ....B Altcode: A candidate for the successor to the Hubble Space Telescope is presented. The telescope is a traditional Cassegrain with a 10-meter diameter monolithic primary, passively cooled optics and a wavelength coverage from the far ultraviolet to mid-infrared. Diffraction-limited imagery is achieved in the visible and ultraviolet through interferometric techniques. The observatory is located in the geosynchronous orbit to minimize environmental constraints and increase observing efficiency. Title: National Optical Astronomy Observatories (NOAO) infrared adaptive optics program. II - Modeling atmospheric effects in adaptive optics systems for astronomical telescopes Authors: Roddier, Francois; Roddier, Claude Bibcode: 1986SPIE..628..298R Altcode: However perfect an adaptive optical system can be, it will never fully correct the image. The effects of amplitude errors due to stellar scintillation, the effects of chromatic errors due to both refraction and diffraction in a two-wavelength system, and the effects of nonisoplanicity, are presently discussed. All these errors are directly related to the height of turbulence layers. An expression is derived for the scale height of turbulence, which should be considered as an important parameter in selecting new sites for astronomical observations. The performance of adaptive optical systems is usually described in terms of Strehl ratios. The results of computations of the whole transfer function for long exposure compensated images are presented. It is shown that the point-spread function for a partially compensated image generally consists of an Airy disk surrounded with a halo. The ratio of the energy in the Airy disk over the energy in the halo is independent of the telescope aperture and provides a better measure of the quality of the compensation. Title: National Optical Astronomy Observatories / NOAO / Infrared Adaptive Optics Program - Part Four - Infrared Background Speckle Noise Induced by Adaptive Optics in Astronomical Telescopes Authors: Roddier, F.; Eisenhardt, P. Bibcode: 1986SPIE..628..314R Altcode: The infrared emission of astronomical sources is buried in a large background due to the thermal emission of the telescope. The real time deformations of an adaptive flexible mirror are likely to produce a spurious modulation of this background, adding noise to the signal. The authors estimate the amount of noise introduced by such a mirror. Title: Fiber-coupled interferometric imaging array. Authors: Roddier, F. Bibcode: 1986JOSAA...3P...6R Altcode: No abstract at ADS Title: Fiber-coupled interferometric imaging array (A) Authors: Roddier, Francois Bibcode: 1986JOSAA...3....6R Altcode: 1986OSAJ....3....6R No abstract at ADS Title: National Optical Astronomy Observatories (NOAO) infrared adaptive optics program. I - General description Authors: Beckers, Jacques M.; Roddier, Francois J.; Eisenhardt, Peter R.; Goad, Larry E.; Shu, Ker-Li Bibcode: 1986SPIE..628..290B Altcode: The authors describe the general principles behind a polychromatic adaptive optics program for astronomy. In this program the atmospheric wavefront distortions are measured at visible wavelengths (700 nm) using an astronomical object in the vicinity of the infrared object of interest. The resulting wavefront corrections are applied to an infrared imaging system which utilizes a two-dimensional detector array. The authors describe the principles of this adaptive optics system. Title: IR Background Speckle Noise Induced by Adaptive Optics in Astronomical Telescopes Authors: Eisenhardt, P.; Roddier, F. Bibcode: 1985BAAS...17Q.901E Altcode: No abstract at ADS Title: An image reconstruction of alpha Orionis. Authors: Roddier, F.; Roddier, C. Bibcode: 1985ApJ...295L..21R Altcode: A description is given of an attempt to reconstruct an image of the star Alpha Orionis from a map of fringe visibilities obtained on November 30, 1980 with the CFH Telescope in Hawaii. The maximum entropy algorithm proposed by Gull and Daniell (1978) was used. The data were obtained through a 90 A bandwidth filter centered at 5350 A - a window chosen because it avoids strong molecular absorption bands in the stellar spectrum. The interferometric image reconstruction indicates that dust condensation may well occur close to the stellar disk. Title: High Angular Resolution Interferometric Observations of Betelgeuse in the Visible Authors: Roddier, F.; Roddier, C.; Karovska, M. Bibcode: 1985ASSL..117...63R Altcode: 1985mlrg.proc...63R A new high angular resolution interferometric technique, based on pupil plane observation and rotation shearing of the wavefront, has been developed in the authors' laboratory and compares favorably with speckle interferometry. A two-dimensional map of the visibility of the fringes produced by Betelgeuse has been obtained from data recorded at the C.F.H. telescope on November 30, 1980, in the continuum at λ = 5348 Å. The map (C. Roddier and F. Roddier, 1983) shows evidence for departure from circular symmetry. It has been interpreted as produced by a stellar disk surrounded with an irregular envelope. The authors present here an attempt to reconstruct an image from these data. Title: On a Possible Close Companion to αOri Authors: Karovska, M.; Noyes, R. W.; Roddier, F.; Nisenson, P.; Stachnik, R. V. Bibcode: 1985BAAS...17..598K Altcode: No abstract at ADS Title: Polychromatic Adaptive Optics for Infrared Telescopes Authors: Beckers, J. M.; Eisenhardt, P.; Goad, L.; Roddier, F. Bibcode: 1985BAAS...17R.571B Altcode: No abstract at ADS Title: IR background speckle noise induced by adaptive optics in astronomical telescopes. Authors: Roddier, F.; Eisenhardt, P. Bibcode: 1985SPIE..556..248R Altcode: The infrared emission of astronomical sources is buried in a large background due to the thermal emission of the telescope. The real time deformations of an adaptive flexible mirror are likely to produce a spurious modulation of this background, adding noise to the signal. The authors estimate the amount of noise introduced by such a mirror. Title: Long-baseline Michelson interferometry with large ground-based telescopes operating at optical wavelengths. II. Interferometry at infrared wavelengths. Authors: Roddier, F.; Lena, P. Bibcode: 1984JOpt...15..363R Altcode: 1984JOp....15..363R The theoretical bases, techniques, and instrumentation applied in long baseline interferometry of astrophysical objects at IR wavelengths are surveyed. Light detection is carried out with single photoelectric sensors functioning in the 1-30 microns window or with one- or two-dimensional CCD device grids which measure the incoming flux. Numerical expressions have been devised to account for single-photon, background and detector intrinsic noise sources and standard noise values have been calculated for each. The SNR and phase stability of sensed image fringes determine if the photoelectric analysis will proceed by synchronous detection or quadratic detection, respectively. The interference will be analyzed either in the image or in terms of the registration on the pupil plane of the detector. Techniques for estimating the image spectral density and limiting magnitudes are reviewed. Applications of long-baseline systems to studying asteroids, comets, star formation, and galactic nuclei are discussed, noting the large advantages available in visible wavelength studies if the instrumentation was space-based. Title: Long-baseline Michelson interferometry with large ground-based telescopes operating at optical wavelengths. I. General formalism. Interferometry at visible wavelengths. Authors: Roddier, F.; Lena, P. Bibcode: 1984JOpt...15..171R Altcode: 1984JOp....15..171R Present knowledge on long baseline interferometry with large telescopes is reviewed, and reasonable estimates are made of the performances which may be expected in the visible range using this technique. The general formalism of this interferometric scheme is discussed, with a detailed examination of aperture size effects. The time and chromatic dependences are presented. Michelson interferometry at visible wavelengths is addressed, including the estimation of the image energy spectrum and of the limiting magnitude, the limits of present technology, and the potential of the technique. Title: PM. 09 Interferometric Image Reconstruction Using the L. D. R. in a Light Bucket Mode Authors: Roddier, F.; Breckinridge, J. B. Bibcode: 1984BAAS...16..832R Altcode: The application of a rotational shear interferometer to the large deployable reflector may lead to very high spatial resolution image reconstruction. It is shown that interferometric techniques could extend the imaging capabilities of the reflector down to the visible where complete image reconstruction, with an angular resolution limit of a few milliarcseconds, may still be achieved to stellar magnitudes as faint as 21. Title: Distributions et transformation de Fourier a l'usage des physiciens et des ingenieurs Authors: Roddier, F. Bibcode: 1984detd.book.....R Altcode: No abstract at ADS Title: Review on Increase in Spatial Resolving Power Authors: Roddier, F. Bibcode: 1984apoa.conf...22R Altcode: No abstract at ADS Title: Special requirements for high angular resolution interferometry. Authors: Roddier, F. Bibcode: 1984ESOC...18..193R Altcode: 1984stfl.work..193R Stringent conditions imposed on the optical quality of the earth's atmosphere by interferometric imaging techniques are reviewed. It is suggested that these conditions be taken into account in any future site testing campaign. Consideration is given to seeing parameters relevant to interferometric imaging, statistics of Fried's parameter, the life time of fringes and speckles, the isoplanatic angle, the turbulence outerscale, and the application to site testing. Title: Measuring atmospheric seeing Authors: Roddier, F. Bibcode: 1984vlti.conf..191R Altcode: 1984vlts.coll..191R; 1984IAUCo..79..191R The techniques available for measurement of image plane, pupil plane, turbulence, and meteorological parameters are reviewed, and their relative merits with respect to applications are assessed. It is inferred that image plane measurements are best suited for correcting observations for image degradation. Pupil plane measurements, on the other hand, are more accurate for comparing seeing conditions between telescopes and sites. Several methods of remote turbulence sounding are also evaluated, including sodar, radar, and Scidar (stellar scintillation sounder). It is suggested that to improve image quality, a combination of remote sensing techniques and pupil plane measurements is most appropriate. Title: High angular resolution observations of alpha Orionis with a rotationshearing interferometer. Authors: Roddier, C.; Roddier, F. Bibcode: 1983ApJ...270L..23R Altcode: A two-dimensional map of the visibility of fringes produced by α Orionis through a rotation shearing interferometer is presented. It shows evidence for a circumstellar envelope and for departure from circular symmetry. Title: Testing seeing quality Authors: Roddier, F. Bibcode: 1983ESOC...17..255R Altcode: 1983vlt..work..255R Problems of good telescope site location to solve image degradation are discussed. Differences between dome seeing, which is related to turbulence within the instrument, and atmospheric seeing which is related to image degradation due to the fluctuations of the atmospheric reflective index are analyzed, stressing the need for an appropriate choice of telescope location. Methods for site testing are presented considering three types of parameters: meteorological (pressure, temperature, and wind profiles), turbulence, and optical (speckle life time and Fried parameter). Good turbulence profiles yield reliable estimates of the image quality and techniques measuring these profiles are covered in detail. Although in situ measurements can be done they are cumbersome, while remote sensing through use of optical sensors seems the most promising. These techniques not only provide accurate estimates of optical quality of the atmosphere but also reveal the atmospheric layers which contribute to image degradation. Relating these turbulent layers to meteorological data yields better estimates of their occurrence frequency and gives hints on how to possibly avoid them by an appropriate site selection. Title: Future possibilities of ground-based interferometry in the visible Authors: Roddier, F. Bibcode: 1983ESOC...17..155R Altcode: 1983vlt..work..155R Attention is given to the performance claims and other relative advantages of three main classes of telescope configurations that have been proposed to increase light collecting area: (1) a single giant telescope of about 16 meter aperture, employing either a single segmented mirror or multiple mirrors, (2) a limited number of large telescopes of approximately 8 m aperture having thin, servocontrolled mirrors, and (3) a large array of 16 telescopes of 4 m aperture. The choice of the most advantageous system is made on the basis of high angular resolution interferometry's requirements, whose criteria include angular resolution, Fourier plane coverage, limiting magnitude, accuracy, and imaging capability. Title: On the origin of speckle boiling and its effects in stellar speckle interferometry. Authors: Roddier, F.; Gilli, J. M.; Lund, G. Bibcode: 1982JOpt...13..263R Altcode: 1982JOp....13..263R An optimum exposure time is formulated for speckle interferometric observations of stellar objects. The exposure interval is constrained by the need to stop as soon as the speckle pattern of the object is captured, yet the aperture must remain open long enough to adequately view what are nominally faint sources. It is shown that the optimum exposure time is related to the time scale of speckle boiling or speckle lifetime. The speckle lifetime is demonstrated to be limited to the ratio of Fried's parameter (1966) to the standard deviation of the wind velocities distribution and the atmospheric turbulence of the earth atmosphere. Theoretical investigations of the effect of a finite exposure time, the space-time correlation of speckle patterns, the wavefront boiling time, and Michelson interferometry and adaptive optics are presented. The results of a laboratory simulation of astronomical speckle boiling are presented, and found to agree with previous works. The effects of atmospheric turbulence being concentrated in a single layer are discussed. Title: On the isoplanatic patch size in stellar speckle interferometry. Authors: Roddier, F.; Gilli, J. M.; Vernin, J. Bibcode: 1982JOpt...13...63R Altcode: 1982JOp....13...63R No abstract at ADS Title: How to achieve diffraction limited resolution with large space telescopes Authors: Roddier, F. Bibcode: 1982AdSpR...2d...3R Altcode: 1982AdSpR...2R...3R Large space telescopes cannot be made diffraction-limited at least for short wavelengths. Methods for reconstructing diffraction-limited images are reviewed including active optics, Michelson stellar interferometry, non-redundant aperture arrays, deconvolution and shearing interferometry. Expressions are given for the signal-to-noise ratio in each case and the result of laboratory simulations are presented. It is concluded that diffraction-limited images could be obtained in the visible up to magnitude 21 with large deployable reflectors planned to be used in the far I.R. or millimetric range. Title: High angular resolution with rotation shearing interferometers: preliminary results and future potentials. Authors: Roddier, F.; Roddier, C. Bibcode: 1982ASSL...92..207R Altcode: 1982IAUCo..67..207R; 1982ialo.coll..207R A rotation-shearing interferometer has been designed and constructed which consists of a beam-splitting cube and two phase-compensated roof prisms giving high-contrast, high-luminosity fringes at any rotation angle. A chromatic lens system provides a pupil image with a magnification proportional to the inverse of the wavelength thus permitting the use of large optical bandwidths; the bandwidth is limited by turbulence to a few hundred Angstroms as in speckle interferometry. Visual estimates of the diameter of the star Betelgeuse (alpha Ori) at 10 wavelengths are presented; observations of other stars are also briefly discussed. Title: Rotation interferometry: a new technique for achieving high angular resolution. Authors: Roddier, C.; Roddier, F.; Vernin, J. Bibcode: 1981siha.conf..165R Altcode: 1982siha.conf..165R No abstract at ADS Title: Atmospheric limitations to high angular resolution imaging. Authors: Roddier, F. Bibcode: 1981siha.conf....5R Altcode: 1982siha.conf....5R The statistics of wavefront perturbations are reviewed, their implications for high-angular resolution imaging are discussed, and expressions are given for the signal-to-noise ratios and the limiting magnitudes in several cases. The described coherence properties of wavefront perturbations include the probability density function, spatial coherence, spatio-temporal coherence, spatio-angular coherence, and spectral coherence. The SNR in high resolution imaging is addressed, including the SNR in the image spectrum, the energy transfer function, the effect of pupil redundancy and sampling, the minimum integration time, and the limiting stellar magnitude in the visible. Title: The effects of atmospheric turbulence in optical astronomy Authors: Roddier, F. Bibcode: 1981PrOpt..19..281R Altcode: Atmospheric turbulence is examined in terms of its effects on optical astronomy. The statistical properties of atmospheric turbulence are explored, considering structure, temperature and humidity fluctuations, and the dependence of the contribution of turbulence to optical propagation with height and time. The statistical properties of the perturbed complex field are analyzed for the output of a thin turbulent layer, multiple and thick layers, and fourth order moments. Long exposure images are considered for the relation between the object and the image, for an expression of the optical transfer function, for resolving power, and for application to Michelson's stellar interferometry. Short exposure images vary with the image energy spectrum and the probability density functions of stellar speckles. Attention is also given to the effects of exposure time and nonisoplanicity effects, optical path fluctuations, stellar scintillation, and applications to high resolution imaging. It is noted that astronomical instruments may become useful for atmospheric remote sensing, as is now done for stellar scintillation. Title: Twin-image holography with spectrally broad light Authors: Roddier, C.; Roddier, F.; Martin, F.; Baranne, A.; Brun, R. Bibcode: 1980JOpt...11..149R Altcode: The bandwidth limitation to incoherent twin-image holography is examined, and a solution to the problem for the reconstruction and recording of turbulence- or aberration-degraded astronomical images is presented. The maximum usable bandwidth to prevent chromatic blurring is shown to vary inversely with the total number of pixels in the reconstructed image; however, it is noted that the use of very short exposures in the restoration of turbulence-degraded images favors an increase in bandwidth. Previously designed achromatic interferometers are indicated, and it is pointed out that the chromatic effect in the hologram irradiance distribution disappears if an image is produced in front of the interferometer with a magnification proportional to the wavelength, as in rotation shearing interferometry. A chromatic lens system based on two meniscus lenses providing a chromatic change in magnification is outlined, and experimental results obtained with the system and demonstrating the utility of the system in increasing fringe numbers are presented. Title: New trends in stellar speckle interferometry. Authors: Roddier, F. Bibcode: 1980SPIE..243...83R Altcode: Recent advances are presented of the stellar speckle interferometer technique, with particular attention given to (1) the extension of the technique to infrared wavelengths, (2) improved calibration of atmospheric effects, and (3) an improved understanding of atmospheric effects. Arrays of detector elements are now available, but they are extremely expensive. Theoretical estimates of the modulation transfer function can be obtained from numerical computations, assuming log-normal statistics for the wavefront perturbations, which was first done by Korff (1973). Improved calculations, which take the central telescope obstruction into account, were made by Roddier (1979) and were found to be in good agreement with the photoelectric measurements made by Aime et al. (1979) in the visible, as well as with infrared measurements obtained by Chelli et al. (1979). The discussion of the atmospheric effects includes the effects of a single thin turbulent layer at a certain altitude above the telescope, moving at a certain wind velocity. Title: Observations of the Sun with interferometry and speckle-interferometry techniques Authors: Roddier, F. Bibcode: 1980fsoo.conf...96R Altcode: No abstract at ADS Title: Speckle and Intensity Interferometry. Applications to Astronomy Authors: Roddier, F. Bibcode: 1980LNP...112..344R Altcode: 1980ipcp.conf..344R No abstract at ADS Title: Statistical determination of a morphological parameter in solar granulation: spatial distribution of granules. Authors: Aime, C.; Martin, F.; Grec, G.; Roddier, F. Bibcode: 1979A&A....79....1A Altcode: Summary. This article is concerned with the study of morphological properties of solar granulation, which are derived from two dimensional harmonic (power spectrum) analysis of the granule position. By use of a morphological model for the granulation, it is shown that the deviations in granules positions from an hexagonal reference structure (Benard Cells) have a gaussian distribution. A mathematical analysis demonstrates that the histograms of intergranular separation found in various literature may be interpreted as Rice-Nakagami distributions. The usefulness of such harmonic techniques is shown for research into ordered or quasi-periodic structures. Key words: solar granulation - harmonic analysis - morphology Title: Modulation Transfer Function for Infra-red Stellar Speckle Interferometry: Evidence for a Log-normal Statistic Authors: Chelli, A.; Lena, P.; Roddier, C.; Roddier, F.; Sibille, F. Bibcode: 1979AcOpt..26..583C Altcode: 1979JMOp...26..583C No abstract at ADS Title: Rotation-shearing interferometry Authors: Roddier, F. Bibcode: 1979hars.proc...32R Altcode: 1979IAUCo..50...32R An approach toward correcting wavefront errors, imaging with a coherence interferometer, is presented. This consists of post detection processing of interferograms in the pupil space. While similar to Michelson interferometry, it allows observation of all the Fourier components of the image at the same time. Imaging through fixed aberrations is covered noting that the signal to noise ratio in incoherent holograms decreases as the square root the number of resolved pixels in the image. Imaging through turbulence is demonstrated with a double point source as the object. While none of the images shows a resolved structure, the double point source is clearly resolved in the restored image with a correct ratio of intensities between the two point sources. Finally, astronomical applications are discussed including use with the 1.52 m telescope of the Haute Provence Observatory. Title: Imaging with a Coherence Interferometer in Optical Astronomy Authors: Roddier, C.; Roddier, F. Bibcode: 1979ASSL...76..175R Altcode: 1979ifcf.coll..175R; 1979IAUCo..49..175R A technique of imaging with a coherence interferometer is described which consists of postdetection processing of interferograms in the pupil space. This technique, also called incoherent holography, consists of observing the interference pattern produced by two superimposed images of the telescope pupil, one being rotated with respect to the other. Imaging through fixed aberrations and imaging through turbulence are discussed. Title: The effects of atmospheric turbulence on the formation of visible and infrared images. Authors: Roddier, F. Bibcode: 1979JOpt...10..299R Altcode: 1979JOp....10..299R The paper briefly reviews the properties of atmospheric turbulence relevant to image formation. Statistics of associated wavefront perturbations are described, and their consequences are examined for both classical and interferometric imaging. Title: Observations of the sun with interferometry and speckle-interferometry techniques. Authors: Roddier, F. Bibcode: 1979MmArc.106...96R Altcode: No abstract at ADS Title: Estimation errors for the covariance determination of stationary and ergodic stochastic processes with a nonzero mean value. Authors: Martin, F.; Borgnino, J.; Aime, C.; Ricort, G.; Roddier, F. Bibcode: 1979JOpt...10...99M Altcode: 1979JOp....10...99M No abstract at ADS Title: Defocusing effects in astronomical speckle interferometry Authors: Roddier, F.; Ricort, G.; Roddier, C. Bibcode: 1978OptCo..24..281R Altcode: Theoretical transfer functions for astronomical speckle interferometry, through a defocused telescope, have been computed assuming a log-normal complex amplitude for the incoming wavefront. They are found to be in reasonable agreement with recently published observations. The theory also applies to the effect of astigmatism. Title: Observations of the Sun with interferometry and speckle interferometry techniques Authors: Roddier, F. Bibcode: 1978fsoo.conf...96R Altcode: No abstract at ADS Title: Experiments for large multi-mirror telescopes. I.- Detection of non radial stellar oscillations. Authors: Roddier, F.; Fossat, E.; Grec, G.; Roddier, C. Bibcode: 1978otf..conf..357R Altcode: Preliminary measurements made with a 2-m telescope equipped with a sodium cell have shown that nonradial oscillations similar to the solar 5-min oscillations could be detected on bright stars with an integration time of three hours and a 5-m telescope. Because of their aberrations, large optical telescopes of the future will act as light collectors rather than imaging devices. An analysis demonstrates how interferometric techniques can be used to obtain good images with a multi-mirror telescope. Title: Experiments for large multi-mirror telescopes. II.- Imaging with a multi-mirror telescope. Authors: Roddier, F.; Roddier, C. Bibcode: 1978otf..conf..359R Altcode: No abstract at ADS Title: One-dimensional stellar and solar speckle interferometry Authors: Aime, C.; Roddier, F. Bibcode: 1977OptCo..21..435A Altcode: A new technique called ``one-dimensional speckle-interferometry'' is analysed. It appears to be a good compromise between standard speckle-interferometry and Michelson interferometry for precise, high resolution astronomical measurements. Title: Defocusing effects in astronomical speckle interferometry. Authors: Roddier, F.; Ricort, G.; Roddier, C. Bibcode: 1977OptCo..24..281R Altcode: No abstract at ADS Title: Seeing effects removal in a Michelson stellar interferometer. Authors: Roddier, C.; Roddier, F. Bibcode: 1976JOSA...66.1347R Altcode: 1976OSAJ...66.1347R There is no unique definition of the fringe contrast in a random structure such as the image given by a Michelson stellar interferometer. A definition is given which leads to a contrast value independent of the seeing conditions provided the wave-front perturbations on the two apertures are uncorrelated. Moreover, if simultaneous observations through a single aperture are available, the seeing effects can be completely removed. Title: Imaging through turbulence with telescope arrays Authors: Aime, C.; Roddier, F. Bibcode: 1976OptCo..19...57A Altcode: By applying speckle-interferometry technique to the synthetic image given by an array of large telescopes, quantitative measurements of object power-spectra can be made in spite of atmospheric turbulence, provided the apertures are sufficiently apart so that the wave-front perturbations remain uncorrelated. The signal-to-noise ratio depends upon the redundancy of the array. Title: On the fringe visibility in a Michelson stellar interferometer. Authors: Roddier, C.; Roddier, F. Bibcode: 1976JOSA...66..580R Altcode: 1976OSAJ...66..580R Speckle interferometry theory is applied to Michelson interferometry, and the fringe contribution in the stellar image Wiener spectrum is calculated as a function of aperture diameter and seeing conditions for an unresolved star. Computing the Wiener spectrum for a turbulence-degraded point-source image facilitates quantitative determination of fringe visibility in Michelson stellar interferometry. Fringe contributions to the image Wiener spectrum become independent of aperture diameters at large apertures. The results encourage the use of long-baseline Michelson interferometry with large telescopes for quantitative measurements of very-small-scale light distributions in stellar sources, with negligible image degradation by atmospheric turbulence. Title: Treatment of astronomical images degraded by atmospheric fluctuations. Authors: Roddier, F. Bibcode: 1976RvPA...11..195R Altcode: No abstract at ADS Title: Effects of the atmosphere in stellar speckle interferometry. Authors: Roddier, F.; Roddier, C. Bibcode: 1976JOSA...66..181R Altcode: 1976OSAJ...66..181R No abstract at ADS Title: The treatment of astronomical images degraded by atmospheric fluctuations. Authors: Roddier, F. Bibcode: 1975AnTel..30..304R Altcode: Atmospheric turbulence can produce speckle distortion in astronomical images. Various methods, based on phase reconstruction and speckle interferometry, are discussed for restoring images thus distorted. It is shown that complete restoration is theoretically possible by means of incoherent-light holography. Title: Principle of production of an acoustic hologram of the solar surface Authors: Roddier, F. Bibcode: 1975CRASB.281...93R Altcode: A procedure is described which permits point-by-point photographic recording of the complex amplitude of photospheric oscillations. Examination of such holograms in coherent light could lead to a visualization of subjacent acoustic sources. The method is based on a previous investigation by Sheeley and Bhatnagar (1971) employing Doppler photography. Title: Influence of exposure time on spectral properties of turbulence-degraded astronomical images. Authors: Roddier, C.; Roddier, F. Bibcode: 1975JOSA...65..664R Altcode: 1975OSAJ...65..664R No abstract at ADS Title: Atmospheric turbulent layers localisation by optical processing of stellar shadow pattern Authors: Martin, F.; Borgnino, J.; Roddier, F. Bibcode: 1975NROpt...6...15M Altcode: An optical information processing technique, commonly used for speckle-pattern analysis, is applied to the study of the motion of shadow patterns associated with stellar scintillation. The intensities of the diffraction patterns produced by several double-exposure photographs are added on a single plate. Interference fringes are observed at right angles to the direction of displacement. Fringe spacing is inversely proportional to the speed of motion. By fitting the velocity deduced from fringe measurements to the results of meteorological wind soundings, an approximate altitude is obtained for the atmospheric turbulence layers producing stellar scintillation. Title: Détection au sol de la turbulence stratosphérique par intercorrélation spatioangulaire de la scintillation stellaire. Authors: Vernin, J.; Roddier, F. Bibcode: 1975CRASB.280..463V Altcode: No abstract at ADS Title: Evidence for Large-Scale Oscillations of the Solar Photosphere Authors: Fossat, E.; Ricort, G.; Aime, C.; Roddier, F. Bibcode: 1974ApJ...193L..97F Altcode: Doppler shifts of the Na D1 line, averaged over large solar areas up to the whole sun, have been recorded with a sodium resonance device. The power spectra of the observed fluctuations show that (1) the 5-minute oscillation has an horizontal coherence of 35,000 km at the level of the sodium line formation; (2) the corresponding peak at 3.3 mHz is not predominant for scales greater than 5'. New oscillations appear with a 10-minute period. Title: Detection of atmospheric turbulent layers by spatiotemporal and spatioangular correlation measurements of stellar-light scintillation. Authors: Rocca, A.; Roddier, F.; Vernin, J. Bibcode: 1974JOSA...64.1000R Altcode: No abstract at ADS Title: Speckle interferometry through small multiple apertures. Michelson stellar interferometer and aperture synthesis in optics. Authors: Roddier, F. Bibcode: 1974OptCo..10..103R Altcode: The use of a Michelson stellar interferometer or multiple-hole interferometers is considered as a special case of speckle interferometry. Formulas are given for the power spectrum of the interference pattern produced by the multiple apertures. The limitation in stellar magnitude is shown to increase with the number of apertures, while it is independent of the telescope size when a large single aperture is used. Title: Correlation measurements on the complex amplitude of stellar plane waves perturbed by atmospheric turbulence Authors: Roddier, C.; Roddier, F. Bibcode: 1973JOSA...63..661R Altcode: 1973OSAJ...63..661R The mutual coherence function (MCF) of the complex amplitude of stellar light waves perturbed by atmospheric turbulence has been determined interferometrically. Results are in good agreement with horizontal laser-beam determinations. Stellar measurements provide quantitative estimations of seeing conditions for astronomical observations. Title: Experimental determination of two-dimensional spatiotemporal power spectra of stellar light scintillation. Evidence for a multilayer structure of the air turbulence in the upper troposphere. Authors: Vernin, J.; Roddier, F. Bibcode: 1973JOSA...63..270V Altcode: No abstract at ADS Title: A Sodium Experiment for Photospheric Velocity Field Observations Authors: Fossat, E.; Roddier, F. Bibcode: 1971SoPh...18..204F Altcode: A method for studying small scale photospheric velocity fields with a balloon experiment is proposed. A sodium resonance cell is used with a diffraction limited telescope. Good pointing accuracy is not necessary. Preliminary results of ground-based observations are given. Title: A Model of the Solar Photospheric Velocity Field Authors: Gonczi, G.; Roddier, F. Bibcode: 1971A&A....11...28G Altcode: The velocity field in the solar photosphere is determined from an analysis of the geometrical properties (asymmetry and general shape) of the profiles of the Sr 4607 line observed by Roddier (1965) with an atomic beam spectrograph. Below an optical depth of 4 x 10-8 (at 5000 A), the adopted model has two adjacent columns with different microturbulence which is anisotrope and increasing with depth. The column with the smallest microturbulence rises with a velocity of 0.7 km/s and the other one descends with a velocity of 0.3 km/s. This model gives profiles of Sr 14607 from the centre to the limb of the solar disk which are in good agreement with the experimental ones, and it is also in good agreement with some recent observations of the photospheric microstructures. Key words: velocity field - turbulence - convection - microturbulence - line profile Title: Line Profiles in Sunspot Umbrae and Penumbrae by Atomic Beam Spectroscopy Authors: Roddier, F. Bibcode: 1971IAUS...43..249R Altcode: No abstract at ADS Title: Interpretation of the East-West Asymmetry of the Initial Appearance of Sunspots Authors: Rix, H.; Roddier, F. Bibcode: 1970A&A.....9..301R Altcode: The East-West asymmetry in the initial appearance of s'mspots is explained, assuming that sunspots begin to form at a level deeper than optical depth unity and move towards the surface of the s'm, by the variation of the photospheric opacity with height combined with the variation of the heliocentric angle as the observation moves from the centre to the limb. This contribution to the asymmetry is the same order of magnitude as the contribution from the classical "foreshortening effect". A conical model of a sunspot is used to include the contribution of these two effects. A comparison of the theory with the observed East-West asymmetry gives a mean ascentional velocity of the sunspots of 3 m/s. This comparison gives further evidence that the evolution of some sunspots is interrupted. Title: A Fourier Spectrum Analysis of Long Samples of Solar Line Oscillations Authors: Gonczi, G.; Roddier, F. Bibcode: 1969SoPh....8..255G Altcode: Sequences of the oscillations of solar lines up to 2 hours 20 min long have been recorded at the same point on the sun. The power spectra show several peaks separated by 0.85 × 10−3 cps on average from each other. A sharp main peak at 3.3 × 10−3 cps (300 sec period) is almost always present. Title: Observation of the Solar Line Oscillations with an Atomic-Beam Spectro-Photometer Authors: Roddier, F. Bibcode: 1967ApJ...147.1113R Altcode: An atomic-beam resonance spectrophotometer has been used with the McMath solar telescope to observe the 300-sec oscillation of velocity in photospheric granules. The Sr 4607 line profile periodically changes between a symmetric profile at the expected wavelength and an asymmetric one shifted to the violet. Title: Étude à haute résolution de quelques raies de Fraunhofer par observation de la résonance optique d'un jet atomique. III Authors: Roddier, F. Bibcode: 1966AnAp...29..639R Altcode: No abstract at ADS Title: The Sodium D Lines in Comet Ikeya-Seki Authors: Livingston, W.; Roddier, F.; Spinrad, H.; Slaughter, C.; Chapman, D. Bibcode: 1966S&T....31...24L Altcode: No abstract at ADS Title: Microturbulence Above the Hydrogen Convection Zone Authors: Roddier, F. Bibcode: 1966IAUTB..12..553R Altcode: No abstract at ADS Title: Micromotions, Macromotions, and Non-LTE Effects Authors: Pecker, J. -C.; Roddier, F. Bibcode: 1965SAOSR.174..437P Altcode: No abstract at ADS Title: Étude à haute résolution de quelques raies de Fraunhofer par observation de la réponse optique d'un jet atomique. I. Réalisation d'un spectrographe à jet atomique. Authors: Roddier, F. Bibcode: 1965AnAp...28..463R Altcode: No abstract at ADS Title: Étude à haute résolution de quelques raies de Fraunhofer par observation de la réponse optique d'un jet atomique. II. Résultats des observations solaires Authors: Roddier, F. Bibcode: 1965AnAp...28..478R Altcode: No abstract at ADS Title: Etude à Haute Résolution du Profil de la Raie λ = 4607.3 Å du Strontium Neutre en Différents Points du Disque Solaire et Mesure des Longeurs d'Onde au Spectrographe à Jet Atomique Authors: Blamont, J. E.; Roddier, F. Bibcode: 1964CRASB.258..449B Altcode: No abstract at ADS Title: Precise Observation of the Profile of the Fraunhofer Strontium Resonance Line. Evidence for the Gravitational Red Shift on the Sun Authors: Blamont, J. E.; Roddier, F. Bibcode: 1961PhRvL...7..437B Altcode: No abstract at ADS