References of "Perrin, G"
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See detailThe Subaru Coronagraphic Extreme Adaptive Optics System: Enabling High-Contrast Imaging on Solar-System Scales
Jovanovic, N.; Martinache, F.; Guyon, O. et al

in Publications of the Astronomical Society of the Pacific (2015), 127

The Subaru Coronagraphic Extreme Adaptive Optics (SCExAO) instrument is a multipurpose high-contrast imaging platform designed for the discovery and detailed characterization of exoplanetary systems and ... [more ▼]

The Subaru Coronagraphic Extreme Adaptive Optics (SCExAO) instrument is a multipurpose high-contrast imaging platform designed for the discovery and detailed characterization of exoplanetary systems and serves as a testbed for high-contrast imaging technologies for ELTs. It is a multiband instrument which makes use of light from 600 to 2500 nm, allowing for coronagraphic direct exoplanet imaging of the inner 3λ/D from the stellar host. Wavefront sensing and control are key to the operation of SCExAO. A partial correction of low-order modes is provided by Subaru's facility adaptive optics system with the final correction, including high-order modes, implemented downstream by a combination of a visible pyramid wavefront sensor and a 2000-element deformable mirror. The well-corrected NIR (y-K bands) wavefronts can then be injected into any of the available coronagraphs, including but not limited to the phase-induced amplitude apodization and the vector vortex coronagraphs, both of which offer an inner working angle as low as 1λ/D. Noncommon path, low-order aberrations are sensed with a coronagraphic low-order wavefront sensor in the infrared (IR). Low noise, high frame rate NIR detectors allow for active speckle nulling and coherent differential imaging, while the HAWAII 2RG detector in the HiCIAO imager and/or the CHARIS integral field spectrograph (from mid-2016) can take deeper exposures and/or perform angular, spectral, and polarimetric differential imaging. Science in the visible is provided by two interferometric modules: VAMPIRES and FIRST, which enable subdiffraction limited imaging in the visible region with polarimetric and spectroscopic capabilities respectively. We describe the instrument in detail and present preliminary results both on-sky and in the laboratory. [less ▲]

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See detailDevelopment and recent results from the Subaru coronagraphic extreme adaptive optics system
Jovanovic, N.; Guyon, O.; Martinache, F. et al

in Ground-based and Airborne Instrumentation for Astronomy V (2014, July 01)

The Subaru Coronagraphic Extreme Adaptive Optics (SCExAO) instrument is one of a handful of extreme adaptive optics systems set to come online in 2014. The extreme adaptive optics correction is realized ... [more ▼]

The Subaru Coronagraphic Extreme Adaptive Optics (SCExAO) instrument is one of a handful of extreme adaptive optics systems set to come online in 2014. The extreme adaptive optics correction is realized by a combination of precise wavefront sensing via a non-modulated pyramid wavefront sensor and a 2000 element deformable mirror. This system has recently begun on-sky commissioning and was operated in closed loop for several minutes at a time with a loop speed of 800 Hz, on ~150 modes. Further suppression of quasi-static speckles is possible via a process called "speckle nulling" which can create a dark hole in a portion of the frame allowing for an enhancement in contrast, and has been successfully tested on-sky. In addition to the wavefront correction there are a suite of coronagraphs on board to null out the host star which include the phase induced amplitude apodization (PIAA), the vector vortex, 8 octant phase mask, 4 quadrant phase mask and shaped pupil versions which operate in the NIR (y-K bands). The PIAA and vector vortex will allow for high contrast imaging down to an angular separation of 1 λ/D to be reached; a factor of 3 closer in than other extreme AO systems. Making use of the left over visible light not used by the wavefront sensor is VAMPIRES and FIRST. These modules are based on aperture masking interferometry and allow for sub-diffraction limited imaging with moderate contrasts of ~100-1000:1. Both modules have undergone initial testing on-sky and are set to be fully commissioned by the end of 2014. [less ▲]

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See detailFIRST, a fibered aperture masking instrument. II. Spectroscopy of the Capella binary system at the diffraction limit
Huby, Elsa ULg; Duchêne, G.; Marchis, F. et al

in Astronomy and Astrophysics (2013), 560

Aims: FIRST is a prototype instrument built to demonstrate the capabilities of the pupil remapping technique, using single-mode fibers and working at visible wavelengths. Our immediate objective is to ... [more ▼]

Aims: FIRST is a prototype instrument built to demonstrate the capabilities of the pupil remapping technique, using single-mode fibers and working at visible wavelengths. Our immediate objective is to demonstrate the high angular resolution capability of the instrument and to show that the spectral resolution of the instrument enables characterization of stellar companions. Methods: The FIRST-18 instrument is an improved version of FIRST-9 that simultaneously recombines two sets of nine fibers instead of one, thus greatly enhancing the (u, v) plane coverage. We report on observations of the binary system Capella at three epochs over a period of 14 months (≳4 orbital periods) with FIRST-18 mounted on the 3 m Shane telescope at Lick Observatory. The binary separation during our observations ranges from 0.8 to 1.2 times the diffraction limit of the telescope at the central wavelength of the spectral band. Results: We successfully resolved the Capella binary system at all epochs, with an astrometric precision as good as 1 mas under the best observing conditions. FIRST also gives access to the spectral flux ratio between the two components directly measured with an unprecedented spectral resolution of R ~ 300 over the 600-850 nm range. In particular, our data allow detection of the well-known overall slope of the flux ratio spectrum, leading to an estimation of the "pivot" wavelength of 0.64 ± 0.01 μm, at which the cooler component becomes the brightest. Spectral features arising from the difference in effective temperature of the two components (specifically the Hα line, TiO, and CN bands) have been used to constrain the stellar parameters. The effective temperatures we derive for both components are slightly lower (5-7%) than the well-established properties for this system. This difference mainly comes from deeper molecular features than those predicted by state-of-the-art stellar atmospheric models, suggesting that molecular line lists used in the photospheric models are incomplete and/or oscillator strengths are underestimated, most likely concerning the CN molecule. Conclusions: These results demonstrate the power of FIRST, which is a fibered pupil remapping-based instrument, in terms of high angular resolution and show that the direct measurement of the spectral flux ratio provides valuable information to characterize little known companions. [less ▲]

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See detailFIRST, a fibered aperture masking instrument. I. First on-sky test results
Huby, Elsa ULg; Perrin, G.; Marchis, F. et al

in Astronomy and Astrophysics (2012), 541

Aims: In this paper we present the first on-sky results with the fibered aperture masking instrument FIRST. Its principle relies on the combination of spatial filtering and aperture masking using single ... [more ▼]

Aims: In this paper we present the first on-sky results with the fibered aperture masking instrument FIRST. Its principle relies on the combination of spatial filtering and aperture masking using single-mode fibers, a novel technique that is aimed at high dynamic range imaging with high angular resolution. Methods: The prototype has been tested with the Shane 3-m telescope at Lick Observatory. The entrance pupil is divided into sub-pupils feeding single-mode fibers. The flux injection into the fibers is optimized by a segmented mirror. The beams are spectrally dispersed and recombined in a non-redundant exit configuration in order to retrieve all contrasts and phases independently. Results: The instrument works at visible wavelengths between 600 nm and 760 nm and currently uses nine of the 30 43 cm sub-apertures constituting the full pupil. First fringes were obtained on Vega and Deneb. Stable closure phases were measured with standard deviations on the order of 1 degree. Closure phase precision can be further improved by addressing some of the remaining sources of systematic errors. While the number of fibers used in the experiment was too small to reliably estimate visibility amplitudes, we have measured closure amplitudes with a precision of 10% in the best case. Conclusions: These first promising results obtained under real observing conditions validate the concept of the fibered aperture masking instrument and open the way for a new type of ground-based instrument working in the visible. The next steps of the development will be to improve the stability and the sensitivity of the instrument in order to achieve more accurate closure phase and visibility measurements, and to increase the number of sub-pupils to reach full pupil coverage. [less ▲]

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See detailHigh Dynamic Range Imaging with the FIRST instrument
Perrin, G.; Lacour, S.; Huby, Elsa ULg et al

Conference (2010, October 01)

A concept to achieve high dynamic range images from the ground is presented. The main idea is to calibrate turbulent fluctuations of wavefronts in a telescope pupil with a fibered fully redundant aperture ... [more ▼]

A concept to achieve high dynamic range images from the ground is presented. The main idea is to calibrate turbulent fluctuations of wavefronts in a telescope pupil with a fibered fully redundant aperture mask. This is the principle of the FIRST instrument whose first prototype version is to see stellar photons in July 2010 at Lick Observatory. Lab results and hopefully first sky results will be presented. [less ▲]

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See detailRound table discussion
Coude Du Foresto, V.; Hummel, C. A.; Perrin, G. et al

in Proceedings of the JENAM 2010 Symposium (2010, September 01)

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See detailPEGASE, an infrared interferometer to study stellar environments and low mass companions around nearby stars
Ollivier, M.; Absil, Olivier ULg; Allard, F. et al

in Experimental Astronomy (2009), 23

PEGASE is a mission dedicated to the exploration of the environment (including habitable zone) of young and solar-type stars (particularly those in the DARWIN catalogue) and the observation of low mass ... [more ▼]

PEGASE is a mission dedicated to the exploration of the environment (including habitable zone) of young and solar-type stars (particularly those in the DARWIN catalogue) and the observation of low mass companions around nearby stars. It is a space interferometer project composed of three free flying spacecraft, respectively featuring two 40 cm siderostats and a beam combiner working in the visible and near infrared. It has been proposed to ESA as an answer to the first ``Cosmic Vision'' call for proposals, as an M mission. The concept also enables full-scale demonstration of space nulling interferometry operation for DARWIN. [less ▲]

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See detailCushing disease : Pituitary microsurgery on hormonal balance
Stevenaert, Achille ULg; Vroonen, Laurent ULg; Perrin, G. et al

in European Neuroendocrine Association - Workshop : Novel insights in the management of Cushing's syndrome (2009)

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See detailDiversity among other worlds: characterization of exoplanets by direct detection (Update of a White Paper submitted to the ESA ExoPlanet Roadmap Advisory Team)
Schneider, J.; Boccaletti, A.; Aylward, A. et al

Report (2008)

The physical characterization of exoplanets will require to take spectra at several orbital positions. For that purpose, a direct imaging capability is necessary. Direct imaging requires an efficient ... [more ▼]

The physical characterization of exoplanets will require to take spectra at several orbital positions. For that purpose, a direct imaging capability is necessary. Direct imaging requires an efficient stellar suppression mechanism, associated with an ultrasmooth telescope. We show that before future large space missions (interferometer, 4-8 m class coronograph, external occulter or Fresnel imager), direct imaging of giant planets and close-by super-Earth are at the cross-road of a high scientific interest and a reasonable feasibility. The scientific interest lies in the fact that super-Earths share common geophysical attributes with Earths. They already begin to be detected by radial velocity (RV) and, together with giant planets, they have a larger area than Earths, making them detectable with a 1.5-2 m class telescope in reflected light. We propose such a (space) telescope be a first step before large direct imaging missions. [less ▲]

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See detailGENIE: a Ground-Based European Nulling Instrument at ESO Very Large Telescope Interferometer
Gondoin, P.; den Hartog, R.; Fridlund, M. et al

in Richichi, A.; Delplancke, F.; Paresce, F. (Eds.) et al The Power of Optical/IR Interferometry: Recent Scientific Results and 2nd Generation Instrumentation (2008)

Darwin is one of the most challenging space projects ever considered by the European Space Agency (ESA). Its principal objectives are to detect Earth-like planets around nearby stars, to analyze the ... [more ▼]

Darwin is one of the most challenging space projects ever considered by the European Space Agency (ESA). Its principal objectives are to detect Earth-like planets around nearby stars, to analyze the composition of their atmospheres and to assess their ability to sustain life as we know it. Darwin is conceived as a space ``nulling interferometer'' which makes use of on-axis destructive interferences to extinguish the stellar light while keeping the off-axis signal of the orbiting planet. Within the frame of the Darwin program, definition studies of a Ground based European Nulling Interferometry Experiment, called GENIE, were completed in 2005. This instrument built around the Very Large Telescope Interferometer (VLTI) in Paranal will test some of the key technologies required for the Darwin Infrared Space Interferometer. GENIE will operate in the L' band around 3.8 microns as a single Bracewell nulling interferometer using either two Auxiliary Telescopes (ATs) or two 8m Unit Telescopes (UTs). Its science objectives include the detection and characterization of dust disks and low-mass companions around nearby stars. [less ▲]

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See detailCurrent generation arrays: current status, getting the most out of them and future development
Akeson, R.; ten Brummelaar, T.; Eisner, J. et al

in “Future Directions for Interferometry” (2006)

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See detailCushing's disease : very long-term results of transsphenoidal, clinical and genetic studies
Stevenaert, Achille ULg; Perrin, G.; Martin, Didier ULg et al

in 12th International Congress of Endocrinology - Abstract book (2004)

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See detailResults of transsphenoidal microsurgery in Cushing's disease
Stevenaert, Achille ULg; Perrin, G.; Martin, Didier ULg et al

Conference (2003, March 29)

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See detailMaladie de Cushing et adénome corticotrope: résultats de la microchirurgie hypophysaire
Stevenaert, Achille ULg; Perrin, G.; Martin, Didier ULg et al

in Neuro-Chirurgie (2002), 48(2-3, Pt 2), 234-265

Between November 1994 and June 2001, 194 patients with Cushing's disease underwent transsphenoidal surgery: 167 patients had adenomectomy, 14 had ante hypophysectomy, 5 had subtotal hypophysectomy, 4 had ... [more ▼]

Between November 1994 and June 2001, 194 patients with Cushing's disease underwent transsphenoidal surgery: 167 patients had adenomectomy, 14 had ante hypophysectomy, 5 had subtotal hypophysectomy, 4 had hemihypophysectomy 4 had central hypophysectomy. Complications occurred in 18 patients (9.3%), including 4 deaths (three were apparently not related to surgery). Remission of disease was achieved in 162 of 190 (85.3%) patients analyzed. Surgical failures were associated with lack of pituitary adenoma, size of the tumor and invasiveness. Among patients with confirmed adenomas, the rate of remission was significantly higher (p<0.01) in patients with microadenomas (92.6%) than in patients with macroadenomas (66.7%). Reoperation in 6 failures was followed by remission in 4 cases. The overall remission rate was 87.4%. In the 162 patients with immediate success, duration of follow-up was 10.0 +/- 5.9 years (m +/- DS; median=10.0). Recurrence of the disease occurred in 24 (14.8%) of 162 patients at a mean 4.8 years (range: 0.8-12.0 years). Our longest sustained remission is 25.6 years. Actuarial analysis indicates that the probability of a patient remaining well 12 years after surgery is 80.0%. It is 86.2% in microadenomas versus 52.5% in macroadenomas and 94.5% in the patients with postoperative hypocortisolism versus 59.2% in the others. [less ▲]

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