Papers by Stephane Brillant
ESO Astrophysics Symposia European Southern Observatory, 2008
We present here a short review of the calibration processes that are currently applied to the ins... more We present here a short review of the calibration processes that are currently applied to the instruments AMBER and MIDI of the VLTI (Very Large Telescope Interferometer) at Paranal. We first introduce the general principles to calibrate the raw data (the “visibilities”) that have been measured by long-baseline optical interferometry. Then, we focus on the specific case of the scientific
The Phase Referenced Imaging and Microarcsecond Astrometry (PRIMA) instrument was recently delive... more The Phase Referenced Imaging and Microarcsecond Astrometry (PRIMA) instrument was recently delivered to the summit of Cerro Paranal and installed as part of the Very Large Telescope Interferometer (VLTI) infrastructure. PRIMA is designed to (i) provide phase-referenced interferometric imaging at milliarcsecond scales, (ii) enable faint star science several magnitudes fainter than the current atmospheric limits of the VLTI, and (iii) provide astrometric measurements at the tens of micro-arcsecond level. PRIMA has successfully seen first fringes and is currently (as of late 2008) undergoing initial commissioning tests.
The Astrophysical Journal, 2015
Proceedings of SPIE - The International Society for Optical Engineering
The ESO Very Large Telescope Interferometer (VLTI) offers the unique access to the combination of... more The ESO Very Large Telescope Interferometer (VLTI) offers the unique access to the combination of the four 8-meter Unit Telescopes (UT) of Cerro Paranal. The quality of the scientific observations in interferometric mode is strongly related to the stability of the optical path difference (OPD) between the telescopes. Vibrations at the level of the telescopes and affecting the mirrors were shown to be an important source of perturbation for the OPD. ESO has thus started an important effort on the UTs and VLTI to tackle this effect. Active controls based on accelerometers and phase measurements have been developed to provide real-time correction of the variation of OPD introduced by vibrations. Systematic studies and measurement of the sources of vibration (instruments, wind, telescope altitude, ...) have been performed. Solutions to reduce the vibrations via design modification and/or new operation configurations are studied and implemented. To ensure good operational conditions, the...
4 planets have been detected so far with the microlensing methode. We will present the observatio... more 4 planets have been detected so far with the microlensing methode. We will present the observational constraints to directly detect the lens and greatly improve our knowledge of the systems. By detecting the lens star we will obtain accurate determination of the mass of the planet and its orbital separation. We use the most extreme case OGLE-2005-BLG-390Lb (∼5.5 Earth mass orbiting a red dwarf at ∼2.6 AU) as an illustration.
Brown dwarfs are important objects because they may provide a missing link between stars and plan... more Brown dwarfs are important objects because they may provide a missing link between stars and planets, two populations that have dramatically different formation history. In this paper, we present the candidate binaries with brown dwarf companions that are found by analyzing binary microlensing events discovered during 2004 - 2011 observation seasons. Based on the low mass ratio criterion of q < 0.2, we found 7 candidate events, including OGLE-2004-BLG-035, OGLE-2004-BLG-039, OGLE-2007-BLG-006, OGLE-2007-BLG-399/MOA-2007-BLG-334, MOA-2011-BLG-104/OGLE-2011-BLG-0172, MOA-2011-BLG-149, and MOA-201-BLG-278/OGLE-2011-BLG-012N. Among them, we are able to confirm that the companions of the lenses of MOA-2011-BLG-104/OGLE-2011-BLG-0172 and MOA-2011-BLG-149 are brown dwarfs by determining the mass of the lens based on the simultaneous measurement of the Einstein radius and the lens parallax. The measured mass of the brown dwarf companions are (0.02 +/- 0.01) M_Sun and (0.019 +/- 0.002) M_...
Optical and Infrared Interferometry II, 2010
The Astronomical Multi-BEam Recombiner (AMBER), has been operational at the Very Large Telescope ... more The Astronomical Multi-BEam Recombiner (AMBER), has been operational at the Very Large Telescope Interferometer (VLTI) for many years. We present here some of the constant improvements we have been providing while still operating the instrument, with a heavy load of visitor and service observing programs, most of the nights of the year. In particular, we present here improvements regarding the
Advances in Stellar Interferometry, 2006
The VLTI has been operating for about 5 years using the VINCI instrument first, and later MIDI. I... more The VLTI has been operating for about 5 years using the VINCI instrument first, and later MIDI. In October 2005 (Period 76) the first Science Operations with the AMBER instrument started, with 14 Open Time proposals in the observing queues submitted by the astronomical community. AMBER, the near-infrared/red focal instrument of the VLTI, operates in the bands J, H, and,
Dome C: Astronomy and Astrophysics Meeting, 2005
Abstract. PLANET, the Probing Lensing Anomaly NETwork, is an international team conducting observ... more Abstract. PLANET, the Probing Lensing Anomaly NETwork, is an international team conducting observations of on-going gravitational microlensing events from five sites in the southern hemisphere. Our primary goal is to detect or to put constraints on sub-stellar companions ...
Observatory Operations: Strategies, Processes, and Systems V, 2014
ABSTRACT This paper presents the recent changes undergone by the Science Operations department of... more ABSTRACT This paper presents the recent changes undergone by the Science Operations department of the ESO Paranal Observatory. This revised science operations model, named SciOps2, aims at improving operations efficiency and quality of the data delivered to our community of users. The changes regarding the new department structure, its staffing, and the distribution of tasks and responsibilities, are described in details, as well as the measured impact of these changes.
Optical and Infrared Interferometry, 2008
The ESO Very Large Telescope Interferometer (VLTI) offers access to the four 8 m Unit Telescopes ... more The ESO Very Large Telescope Interferometer (VLTI) offers access to the four 8 m Unit Telescopes (UT) and the four 1.8 m Auxiliary Telescopes (AT) of the Paranal Observatory located in the Atacama Desert in northern Chile. The fourth AT has been delivered to operation in December 2006, increasing the flexibility and simultaneous baselines access of the VLTI. Regular science operations are now carried on with the two VLTI instruments, AMBER and MIDI. The FINITO fringe tracker is now used for both visitor and service observations with ATs and will be offered on UTs in October 2008, bringing thus the fringe tracking facility to VLTI instruments. In parallel to science observations, technical periods are also dedicated to the characterization of the VLTI environment, upgrades of the existing systems, and development of new facilities. We will describe the current status of the VLTI and prospects on future evolution.
Optical and Infrared Interferometry II, 2010
Multiple Application Curvature Adaptive Optics (MACAO) systems are used at the coudé focus of the... more Multiple Application Curvature Adaptive Optics (MACAO) systems are used at the coudé focus of the unit telescopes (UTs) at the La-Silla Paranal Observatory, Paranal, to correct for the wave-front aberrations induced by the atmosphere. These systems are in operation since 2005 and are designed to provide beams with 10 mas residual rms tip-tilt error to the VLTI laboratory. We have initiated several technical studies such as measuring the Strehl ratio of the images recorded at the guiding camera of the VLTI, establishing the optimum setup of the MACAO to get collimated and focused beam down to the VLTI laboratory and to the instruments, and ascertaining the data generated by the real time computer, all aimed at characterizing and improving the overall performance of these systems. In this paper we report the current status of these studies.
Optical and Infrared Interferometry III, 2012
The ESO Very Large Telescope Interferometer (VLTI) offers access to the four 8-m Unit Telescopes ... more The ESO Very Large Telescope Interferometer (VLTI) offers access to the four 8-m Unit Telescopes (UT) and the four 1.8-m Auxiliary Telescopes (AT) of the Paranal Observatory located in the Atacama Desert in northern Chile. The two VLTI instruments, MIDI and AMBER deliver regular scientific results. In parallel to the operation, the instruments developments are pursued, and new modes are studied and commissioned to offer a wider range of scientific possibilities to the community and increase sensitivity. New configurations of the ATs have been offered and are frequently discussed with the science users of the VLTI and implemented to optimize the scientific return. The PRIMA instrument, bringing astrometry capability to the VLTI and phase referencing to the instruments is being commissioned. The visitor instrument PIONIER is now fully operational and bringing imaging capability to the VLTI.
Optical and Infrared Interferometry II, 2010
The ESO Very Large Telescope Interferometer (VLTI) offers access to the four 8-m Unit Telescopes ... more The ESO Very Large Telescope Interferometer (VLTI) offers access to the four 8-m Unit Telescopes (UT) and the four 1.8-m Auxiliary Telescopes (AT) of the Paranal Observatory located in the Atacama Desert in northern Chile. The two VLTI instruments, MIDI and AMBER deliver regular scientific results. In parallel to the operation, the instruments developments are pursued, and new modes are
Optical and Infrared Interferometry II, 2010
The ESO Very Large Telescope Interferometer (VLTI) offers the unique access to the combination of... more The ESO Very Large Telescope Interferometer (VLTI) offers the unique access to the combination of the four 8-meter Unit Telescopes (UT) of Cerro Paranal. The quality of the scientific observations in interferometric mode is strongly related to the stability of the optical path difference (OPD) between the telescopes. Vibrations at the level of the telescopes and affecting the mirrors were shown to be an important source of perturbation for the OPD. ESO has thus started an important effort on the UTs and VLTI to tackle this effect. Active controls based on accelerometers and phase measurements have been developed to provide real-time correction of the variation of OPD introduced by vibrations. Systematic studies and measurement of the sources of vibration (instruments, wind, telescope altitude, ...) have been performed. Solutions to reduce the vibrations via design modification and/or new operation configurations are studied and implemented. To ensure good operational conditions, the levels of vibrations are regularly monitored to control any environmental change. This document will describe the modifications implemented and foreseen and give a status of the VLTI-UT vibrations evolution.
Ground-based and Airborne Telescopes V, 2014
ABSTRACT The ESO Very Large Telescope Interferometer (VLTI) using the Unit Telescope (UT) was str... more ABSTRACT The ESO Very Large Telescope Interferometer (VLTI) using the Unit Telescope (UT) was strongly affected by vibrations since the first observations. Investigation by ESO on that subject had started in 2007, with a considerable effort since mid 2008. An important number of investigations on various sub-systems (On telescope: Guiding, Passive supports, Train Coude, insulation of electronics cabinets; On Instruments: dedicated campaign on each instruments with a special attention on the ones equipped with Close Cycle Cooler) were realized. Vibrations were not only recorded and analyzed using the usual accelerometers but also using on use sub-systems as InfRared Image Sensor (IRIS) and Multiple Applications Curvature Adaptive Optics (MACAO) and using a specific tool developed for vibrations measurements Mirror vibrAtion Metrology systeM for the Unit Telescope (MAMMUT). Those tools and systems have been used in order to improve the knowledge on telescope by finding sources. The sources whenever it was possible were damped. As known for years, instruments are still the principal sources of vibrations, for the majority of the UT. A special test in which 2 UTs instruments were completely shut down was realized to determine the minimum Optical Path Length (OPL) achievable. Vibrations is now a part of the instruments interface document and during the installation of any new instrument (KMOS) or system (AOF) a test campaign is realized. As a result some modifications (damping of CCC) can be asked in case of non-compliance. To ensure good operational conditions, levels of vibrations are regularly recorded to control any environmental change.
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Papers by Stephane Brillant