Showing papers by "David Mouillet published in 2008"
TL;DR: The SPHERE (Spectro-Polarimetric High-contrast Exoplanet Research) planet finder instrument for ESO's VLTtelescope, scheduled for first light in 2011, aims to detect giant extra-solar planets in the vicinity of bright stars by the aid of an extreme-AO turbulence compensation system and to characterize the objects found through spectroscopic and polarimetric observations.
Abstract: The SPHERE (Spectro-Polarimetric High-contrast Exoplanet Research) planet finder instrument for ESO's VLT
telescope, scheduled for first light in 2011, aims to detect giant extra-solar planets in the vicinity of bright stars by the aid
of an extreme-AO turbulence compensation system and to characterize the objects found through spectroscopic and
polarimetric observations. Dual imaging observations within the Y, J, H and Ks atmospheric windows (~0.95 - 2.32μm)
will be done by the aid of the IRDIS cryogenic camera. We describe briefly the science goals of IRDIS and present its
system architecture. Current status of the instrument design is presented, and expected performance is described in terms
of end-to-end simulations.
241 citations
TL;DR: The SPHERE project as discussed by the authors is a project to equip the VLT with a second-generation instrument capable of delivering true images of true extrasolar planets, and the development strategy for creating a coherent software that allows to achieve high observation fidelity is discussed.
Abstract: TheSPHEREprojectisaESOsecondgenerationinstrumentwhichaimstodetectgiantextra-solarplanetsinthevicinityofbrightstars andto characterisethe objects foundthroughspectroscopicandpolarimetricobservations.TechnicaltolerancesarethetightesteverforaninstrumentinstalledattheVLT,andSPHEREdemandsaratheruniqueDRHsoftwarepackagetoaccompany the data from the observation preparation to the search for planetary signals. This paper addresses the currentstatus of the data reduction and handling system (DRHS) for the SPHERE instruments. It includes descriptions of thecalibration and science data, reduction steps and their data products. The development strategy for creating of a coherentsoftware that allows to achieve high observationef ciency is brie y discussed.Keywords: SPHERE, data reduction,pipelines, planet nding 1. INTRODUCTION SPHERE ( S pectro- P olarimetric H igh-contrast E xoplanetResearch)is a projecttoequiptheVLTwith asecond-generationinstrument capable of delivering true images of true extrasolar planets.
120 citations
TL;DR: The ZIMPOL instrument as mentioned in this paper is a single-beam polarimeter that achieves very high polarimetric accuracy using fast polarization modulation and demodulating CCD detectors, which can detect Jupiter-sized planets in close orbit around the brightest nearby stars.
Abstract: The ESO planet finder instrument SPHERE will search for the polarimetric signature of the reflected light from
extrasolar planets, using a VLT telescope, an extreme AO system (SAXO), a stellar coronagraph, and an imaging
polarimeter (ZIMPOL). We present the design concept of the ZIMPOL instrument, a single-beam polarimeter
that achieves very high polarimetric accuracy using fast polarization modulation and demodulating CCD detectors.
Furthermore, we describe comprehensive performance simulations made with the CAOS problem-solving
environment. We conclude that direct detection of Jupiter-sized planets in close orbit around the brightest nearby
stars is achievable with imaging polarimetry, signal-switching calibration, and angular differential imaging.
94 citations
TL;DR: In this paper, the authors studied the active giant V390 Aur using spectropolarimetry to obtain direct and simultaneous measurements of the magnetic field and the activity indicators in order to infer the origin of the activity.
Abstract: Aims We have studied the active giant V390 Aur using spectropolarimetry to obtain direct and simultaneous measurements of the magnetic field and the activity indicators in order to infer the origin of the activity Methods We used the new spectropolarimeter NARVAL at the Bernard Lyot Telescope (Observatoire du Pic du Midi, France) to obtain a series of Stokes I and Stokes V profiles Using the LSD technique we were able to detect the Zeeman signature of the magnetic field in each of our 5 observations and to measure its longitudinal component Using the wide wavelength range of the spectra we could monitor the Call K&H and IR triplet, as well as the H α lines which are activity indicators The Stokes I LSD profiles enabled us to detect and measure the profiles of two weak stellar companions Results From five observations obtained from November 2006 to March 2007, we deduce that the magnetic field has a complex structure which evolves with time and is reminiscent of a dynamo-induced magnetic field The activity indicators also present day to day variations, but their behaviour does not completely follow the magnetic field variations, because their longitudinal component can cancel the contribution of complex magnetic features There is a significant difference between the magnetic field observed on November 27, 2006 and on March 15, 2007, at the same rotational phase, but with an interval of 10 rotations The behaviour of the activity indicators together with the measured enhanced magnetic field on March 15, 2007 support the idea of a change in the field topology Analysis (RV and EW) of the absorption components of the Stokes I LSD profile shows that the secondary of the visual wide orbit binary ADS 3812 is itself a spectroscopic binary, and suggests that the synchronization effect does not play role for V390 Aur (the primary), and that the giant should be considered as effectively single with regard to its fast rotation and activity
35 citations
TL;DR: In this article, an end-to-end model was used to analyze the sensitivity to various parameters (WFE, alignment of the coronagraph, differential aberrations) and to put some specifications on the sub-systems.
Abstract: SPHERE (Spectro Polarimetric High contrast Exoplanet REsearch), the planet finder instrument for the VLT is designed to study relatively bright extrasolar giant planets around young or nearby stars. SPHERE is a set of three instruments fed by the same AO-system, two of them share the same coronagraph. This complex system has been modeled with Fourier Optics to investigate the performance of the whole instrument. In turns, this end-to-end model was useful to analyze the sensitivity to various parameters (WFE, alignment of the coronagraph, differential aberrations) and to put some specifications on the sub-systems. This paper presents some example of sensitivity analysis and some contrast performance of the instruments as a function of the flux for the main observing mode of SPHERE: the Dual Band Imaging (DBI), equivalent to the Spectral Differential Imaging technique.
25 citations
TL;DR: The 2nd generation VLT instrument SPHERE will include an integral field spectrograph to enhance the capabilities of detection of planetary companions close to bright stars as mentioned in this paper, and is foreseen to work in near============IR (0.95-1.65 micron) at low spectral resolution
Abstract: The 2nd generation VLT instrument SPHERE will include an integral field spectrograph to enhance the capabilities
of detection of planetary companions close to bright stars. SPHERE-IFS is foreseen to work in near
IR (0.95-1.65 micron) at low spectral resolution. This paper describes the observing strategies, the adopted
hardware solutions for calibrating the instrument, and the data reduction procedures that are mandatory for the
achievement of the extreme contrast performances for which the instrument is designed.
6 citations
TL;DR: In this article, the apodizer characterization (average transmission radial profile, global reflectivity and transmittivity in the visible), ALC nulling performances compared with expectations, sensitivity of the ALC performances to misalignments of its components.
Abstract: We present some of the High Dynamic Range Imaging activities developed around the coronagraphic test-bench of the Laboratoire A. H. Fizeau (Nice). They concern research and development of an Apodized Lyot Coronagraph (ALC) for the VLT-SPHERE instrument and experimental results from our testbed working in the visible domain. We determined by numerical simulations the specifications of the apodizing filter and searched the best technological process to manufacture it. We present the results of the experimental tests on the first apodizer prototype in the visible and the resulting ALC nulling performances. The tests concern particularly the apodizer characterization (average transmission radial profile, global reflectivity and transmittivity in the visible), ALC nulling performances compared with expectations, sensitivity of the ALC performances to misalignments of its components.
4 citations
TL;DR: The Spectro-Polarimetric High-contrast Exoplanet Research (SPHERE) instrument for the VLT is designed for discovering and studying new extra-solar giant planets orbiting nearby stars by direct imaging as discussed by the authors.
Abstract: The Spectro-Polarimetric High-contrast Exoplanet Research (SPHERE) instrument for the VLT is designed for discovering and studying new extra-solar giant planets orbiting nearby stars by direct imaging In this paper, we describe the philosophy behind the SPHERE baseline data processing sequences dealing with calibration observations, and how these can affect the reduction of subsequent calibrations and scientific data Additionally, we present the result of our detector simulations and the first tests of data reduction recipe prototypes
3 citations
TL;DR: The SPHERE project as discussed by the authors is an exo-solar planet imager, which aims to detect giant exosolar planets in the vicinity of bright stars and to characterize them through spectroscopic and polarimetric observations.
Abstract: The SPHERE is an exo-solar planet imager, which goal is to detect giant exo-solar planets in the vicinity of bright stars and to characterize them through spectroscopic and polarimetric observations. It is built by a consortium of 11 institutes from five countries. Rather than a traditional instrument, it is a complete system with a core made of an extreme-Adaptive Optics (AO) turbulence correction, pupil tracker and interferential coronagraphs feeding 3 different science instruments: working in Near Infrared Y, J, H and Ks bands (0.95 – 2.32µm) and in visible (0.5 – 0.9µm) light. In this paper, we focus on project organization matters like the make-up of the consortium and the decision flow. We try to identify if the management is adequate to the size and scope of the project and the consortium that is in charge of developing it. Our view regarding the organization of future multi-site complex fast track projects are presented.
1 citations
TL;DR: In this paper, an end-to-end model was used to analyze the sensitivity to various parameters (WFE, alignment of the coronagraph, differential aberrations) and to put some specifications on the sub-systems.
Abstract: SPHERE (Spectro Polarimetric High contrast Exoplanet REsearch), the planet finder instrument for the VLT is designed to study relatively bright extrasolar giant planets around young or nearby stars. SPHERE is a set of three instruments fed by the same AO-system, two of them share the same coronagraph. This complex system has been modeled with Fourier Optics to investigate the performance of the whole instrument. In turns, this end-to-end model was useful to analyze the sensitivity to various parameters (WFE, alignment of the coronagraph, differential aberrations) and to put some specifications on the sub-systems. This paper presents some example of sensitivity analysis and some contrast performance of the instruments as a function of the flux for the main observing mode of SPHERE: the Dual Band Imaging (DBI), equivalent to the Spectral Differential Imaging technique.
1 citations
TL;DR: An experimental frame combination pipeline for ultra high-contrast imaging with systems like the upcoming VLT SPHERE instrument is developed, meant to be robust at dealing with data that may contain non-ideal effects like sub-pixel pointing errors, missing data points, non-symmetrical noise sources, arbitrary geometric distortions, and rapidly changing point spread functions.
Abstract: We summarize here an experimental frame combination pipeline we developed for ultra high-contrast imaging with systems like the upcoming VLT SPHERE instrument. The pipeline combines strategies from the Drizzle technique, the Spitzer IRACproc package, and homegrown codes, to combine image sets that may include a rotating field of view and arbitrary shifts between frames. The pipeline is meant to be robust at dealing with data that may contain non-ideal effects like sub-pixel pointing errors, missing data points, non-symmetrical noise sources, arbitrary geometric distortions, and rapidly changing point spread functions. We summarize in this document individual steps and strategies, as well as results from preliminary tests and simulations.
TL;DR: In this paper, an experimental frame combination pipeline was developed for ultra high-contrast imaging with systems like the upcoming VLT SPHERE instrument, which combines strategies from the Drizzle technique, the Spitzer IRACproc package, and homegrown codes, to combine image sets that may include a rotating field of view and arbitrary shifts between frames.
Abstract: We summarize here an experimental frame combination pipeline we developed for ultra high-contrast imaging with systems like the upcoming VLT SPHERE instrument. The pipeline combines strategies from the Drizzle technique, the Spitzer IRACproc package, and homegrown codes, to combine image sets that may include a rotating field of view and arbitrary shifts between frames. The pipeline is meant to be robust at dealing with data that may contain non-ideal effects like sub-pixel pointing errors, missing data points, non-symmetrical noise sources, arbitrary geometric distortions, and rapidly changing point spread functions. We summarize in this document individual steps and strategies, as well as results from preliminary tests and simulations.