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172 results on '"Francois Rigaut"'

151. Adaptive optics prototype system for IR astronomy II: first observing results

Author

P. Kern, Fritz Merkle, Pierre Léna, Gérard Rousset, and Francois Rigaut

Subjects
Physics, Infrared astronomy, business.industry, Detector, Noise (electronics), law.invention, Telescope, Optics, Signal-to-noise ratio, law, K band, Sensitivity (control systems), business, Adaptive optics, Remote sensing
Abstract

Observational results obtained at a 1.52-m telescope in the near-infrared wavelength range of 1.6-5 micron with the use of an adaptive-optics prototype system are reviewed. The purpose of the experiment is to evaluate the correction performance of adaptive optics under actual turbulence conditions at an astronomical site. The observations demonstrate that the full gain in resolution can be obtained. A significant gain in sensitivity is observed, and it is shown that a considerable improvement in signal-to-noise ratio can be achieved due to the bright maximum of sharpened images in all cases where the signal-to-noise ratio is set by background or detector noise.

Published
1990

152. 3.33. A close look at NGC1068 by adaptive optics: dust torus and micro-spiral structure

Author

Olivier Lai, Danielle Alloin, Daniel Rouan, and Francois Rigaut

Subjects
Physics, Active galactic nucleus, Opacity, Bar (music), Astronomy, Torus, Astrophysics, Unified Model, Spiral (railway), Adaptive optics, Parsec
Abstract

As the closest Seyfert nucleus, NGC 1068 is a key object to establish on firm grounds the model of active galactic nuclei (AGN). Two important questions relative to AGNs are : i) can we actually see the parsec-scale torus of dust and molecular gas around the central engine predicted by the popular Unified Model model (e.g. Antonucci, 1993)?; ii) how the gas is brought down to the parsec scale to feed the monster, and, in particular, is there a micro spiral/bar system that could produce the required torque ? Adaptive Optics in the near-IR has potential advantages to make a significant progress in those two questions : the low dust opacity and the excellent angular resolution.

Published
1998

153. Interferometric Coupling of the Keck Telescopes with Single-Mode Fibers

Author

Stephen T. Ridgway, F. Dauny, Olivier Guyon, Jean Guerin, J. Gathright, Peter Wizinowich, C. Collin, J. Nishikawa, Francois Rigaut, Katherine C. Roth, M. Hrynevych, D. Ziegler, Guy Perrin, P. Fédou, J. Crétenet, Sébastien Vergnole, Andrew J. Adamson, Laurent Delage, C. Berthod, C. Deléglise, M. Marteaud, B.-T. Melse, Julien Woillez, C. Marlot, Pierre Léna, T. Goeltzenlichter, Takayuki Kotani, D. Le Mignant, Alan T. Tokunaga, B. Brient, R. Hulin, Frederic H. Chaffee, Jean-Michel Reess, Olivier Lai, François Reynaud, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Pôle Astronomie du LESIA, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Ingénieurs, Techniciens et Administratifs, W. M. Keck Observatory, Canada-France-Hawaii Telescope Corporation (CFHT), National Research Council of Canada (NRC)-Centre National de la Recherche Scientifique (CNRS)-University of Hawai'i [Honolulu] (UH), Institut de Recherche en Communications Optiques et Microondes (IRCOM), Université de Limoges (UNILIM)-Centre National de la Recherche Scientifique (CNRS), United Kingdom Infra-Red Telescope, Hilo, Division technique INSU/SDU (DTI), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Galaxies, Etoiles, Physique, Instrumentation (GEPI), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Pôle instrumental, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Subaru Telescope, National Astronomical Observatory of Japan (NAOJ), National Optical Astronomy Observatory, Tucson (NOAO), Gemini Observatory, and Institute for Astronomy, University of Hawaii

Subjects
Coupling, Physics, Multidisciplinary, Wavelength range, business.industry, Astrophysics::Instrumentation and Methods for Astrophysics, Single-mode optical fiber, Astrophysics::Cosmology and Extragalactic Astrophysics, Interferometry, Optics, Interference (communication), Mauna kea, Observatory, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], business, Astrophysics::Galaxy Astrophysics
Abstract

Here we report successful interferometric coupling of two large telescopes with single-mode fibers. Interference fringes were obtained in the 2- to 2.3-micrometer wavelength range on the star 107 Herculis by using the two Keck 10-meter telescopes, each feeding their common interferometric focus with 300 meters of single-mode fibers. This experiment demonstrates the potential of fibers for future kilometric arrays of telescopes and is the first step toward the 'OHANA (Optical Hawaiian Array for Nanoradian Astronomy) interferometer at the Mauna Kea observatory in Hawaii. It opens the way to sensitive optical imagers with resolutions below 1 milli‐arc second. Our experimental setup can be directly extended to large telescopes separated by many hundreds of meters.

Published
2006

154. The Stellar Content Near the Galactic Center

Author

T. J. Davidge, D. A. Simons, David Crampton, René Doyon, and Francois Rigaut

Subjects
Physics, Space and Planetary Science, Astrophysics (astro-ph), Content (measure theory), Galactic Center, FOS: Physical sciences, Astronomy and Astrophysics, Angular resolution, Astrophysics
Abstract

High angular resolution J, H, K, and L' images are used to investigate the stellar content within 6 arcsec of SgrA*. The data, which are complete to K ~ 16, are the deepest multicolor observations of the region published to date., Comment: 34 pages, including 12 figures

Published
1997

155. Estimation of the adaptive optics long-exposure point-spread function using control loop data

Author

Jean-Pierre Veran, Daniel Rouan, Francois Rigaut, and Henri Maitre

Subjects
Wavefront, Point spread function, Physics, business.industry, Astrophysics::Instrumentation and Methods for Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Atomic and Molecular Physics, and Optics, Deformable mirror, Synchronization, Electronic, Optical and Magnetic Materials, law.invention, Telescope, Optics, law, Control system, Computer Vision and Pattern Recognition, business, Adaptive optics, Image restoration
Abstract

Astronomical images obtained with adaptive optics systems can be enhanced by using image restoration techniques. However, this usually requires an accurate knowledge of the system point-spread function (PSF) which is variable in time. We present a method to estimate the PSF related to each image, using data from the adaptive optics control computer, namely, the wave-front sensor measurements and the commands to the deformable mirror, accumulated in synchronization with the acquisition. This method requires no extra observing time and has been successfully tested on PUEO, the Canada–France–Hawaii Telescope adaptive optics system. With this system, accurate PSF estimations could be achieved for guide stars of magnitude 13 or brighter.

Published
1997

156. High Spatial Resolution Near-Infrared Imaging of the Central Regions of M31

Author

Francois Rigaut, T. J. Davidge, René Doyon, and David Crampton

Subjects
Physics, Luminous infrared galaxy, Barred spiral galaxy, Space and Planetary Science, High spatial resolution, Elliptical galaxy, Astronomy, Astronomy and Astrophysics, Near infrared imaging, Astrophysics, Interacting galaxy, Galaxy
Published
1997

157. Toward a conceptual design for MAVIS

Author

Francois Rigaut, David Brodrick, Guido Agapito, Valentina Viotto, Cedric Plantet, Bernardo Salasnich, Mcdermid, Richard M., Giovanni Cresci, Simon Ellis, Matteo Aliverti, Simone Antoniucci, Andrea Balestra, Andrea Baruffolo, Maria Bergomi, Marco Bonaglia, Giuseppe Bono, Lorenzo Busoni, Elena Carolo, Simonetta Chinellato, Gayandhi De Silva, Simone Esposito, Daniela Fantinel, Jacopo Farinato, Thierry Fusco, Dionne Haynes, Anthony Horton, Gaston Gausachs, James Gilbert, Damien Gratadour, Davide Greggio, Marco Gullieuszik, Pierre Haguenauer, Visa Korkiakoski, Demetrio Magrin, Laura Magrini, Luca Marafatto, Helen McGregor, Trevor Mendel, Stephanie Monty, Benoit Neichel, Fernando Pedichini, Enrico Pinna, Elisa Portaluri, Kalyan Radhakrishnan, Roberto Ragazzoni, David Robertson, Christian Schwab, Rob Sharp, Marco Stangalini, Stefan Stroebele, Elliott Thorn, Annino Vaccarella, Daniele Vassallo, Sudharshan Venkatesan, Lew Waller, Stacy Warner, Frederic Zamkotsian, and Hao Zhang

158. Analytical model for Shack-Hartmann-based adaptive optics systems

Author

Jean-Pierre Veran, Olivier Lai, and Francois Rigaut

Subjects
Point spread function, business.industry, Computer science, Computation, Phase (waves), Spectral density, Systems modeling, Residual, symbols.namesake, Optics, Fourier transform, symbols, business, Adaptive optics, Algorithm
Abstract

In this paper, we present a novel approach to modeling Shack-Hartmann-based adaptive optics (AO) system which allow to easily predict their performance. The idea is to start for the power spectral density (PSD) of the turbulent phase and to derive the PSD of the compensated phase by taking into account the various errors affecting the AO correction, which can be expressed analytically in the Fourier domain. Once the PSD of the compensated phase is known, the computation of the residual point spread function is straightforward.

160. ULTIMATE-subaru: Wide-field near-infrared surveyor with GLAO at subaru telescope

Author

Yusei Koyama, Ian Price, Yutaka Hayano, Nobuo Arimoto, Masayuki Akiyama, Tadayuki Kodama, Yosuke Minowa, Shin Oya, Takashi Hattori, Ikuru Iwata, Kentaro Motohara, Michitoshi Yoshida, Ichi Tanaka, Nicholas Herrald, Celine d'Orgeville, Christophe Clergeon, and Francois Rigaut

Subjects
Physics, Near-infrared spectroscopy, Astronomy, Instrumentation (computer programming), Adaptive optics, Subaru Telescope, Wide field

161. Comparison of vibration mitigation controllers for adaptive optics systems

Author

Benoit Neichel, James Osborn, Andrés Guesalaga, Dani Guzman, and Francois Rigaut

Subjects
Wavefront, business.industry, Turbulence, Computer science, Kalman filter, Band-stop filter, Residual, Atomic and Molecular Physics, and Optics, Deformable mirror, Wind speed, law.invention, Vibration, Telescope, Optics, law, Integrator, Electrical and Electronic Engineering, business, Adaptive optics, Spectroscopy, Engineering (miscellaneous)
Abstract

Vibrations are detrimental to the performance of modern adaptive optics (AO) systems. In this paper, we describe new methods tested to mitigate the vibrations encountered in some of the instruments of the Gemini South telescope. By implementing a spectral analysis of the slope measurements from several wavefront sensors and an imager, we can determine the frequencies and magnitude of these vibrations. We found a persistent vibration at 55 Hz with others occurring occasionally at 14 and 100 Hz. Two types of AO controllers were designed and implemented, Kalman and H∞, in the multiconjugate AO tip-tilt loop. The first results show a similar performance for these advanced controllers and a clear improvement in vibration rejection and overall performance over the classical integrator scheme. It is shown that the reduction in the standard deviation of the residual slopes (as measured by wavefront sensors) is highly dependent on turbulence, wind speed, and vibration conditions, ranging--in terms of slopes RMS value--from an almost negligible reduction for high speed wind to a factor of 5 for a combination of low wind and strong vibrations.

168. MAVIS: Adaptive Optics Module Analysis Report - PDR

Author

VIOTTO, VALENTINA, PINNA, Enrico, AGAPITO, Guido, PLANTET, Cedric Antoine Adrien Gabriel, GREGGIO, Davide, ALIVERTI, Matteo, COLAPIETRO, MIRKO, BONAGLIA, Marco, Brian Taylor, Antony Galla, Stefan Stroebele, ITA, DEU, AUS, D. Brodrick, J. Cranney, P. Haguenauer, F. Rigaut, B. Salasnich, S. Ströbele, I. Vaughn, and Francois Rigaut

Published
2023

170. MAVIS: Deformable Mirror Technology Stability Analysis - PDR

Author

VIOTTO, VALENTINA, DM tiger team, ITA, DEU, AUS, David Brodrick, and Francois Rigaut

Abstract

The current standard Deformable Mirror (DM) technology suffers from a creep effect, in which the actuators, if not checked by a direct measurement of their positions (as in the central area seen by the LGS close loop) will “creep”, i.e. slowly drift as a function of their past command history. The purpose of this document is to list the possible consequences of this effect and quantify their impact on MAVIS (performance, function, etc).

Published
2022

171. MAVIS Design Description - Phase A

Author

SALASNICH, Bernardo, Gausachs,Gaston, Vaccarella, Annino, Haynes, Dionne, Haguenauer, Pierre, BERGOMI, Maria, VIOTTO, VALENTINA, Churilov, V., McDermid, Richard, Brodrick, David, Rigaut, Francois, AUS, David Brodrick, and Francois Rigaut

Published
2020

172. MAVIS Technical Budget - Phase A

Author

AGAPITO, Guido, VIOTTO, VALENTINA, PLANTET, Cedric Antoine Adrien Gabriel, GREGGIO, Davide, Zang, Hao, Gausachs, Gaston, Ellis, Simon, Schwab, Christian, Korkiakoski, Visa, Brodrick, David, AUS, David Brodrick, and Francois Rigaut

Published
2020

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