VANNIER , Martin

We present here three recipes for getting better images with optical interferometers. Two of them, Low- Frequencies Filling and Brute-Force Monte Carlo were used in our participation to the Interferometry Beauty Contest this year and can be applied to classical imaging using V 2 and closure phases. These two addition to image reconstruction...

The first astrophysical results of the VLTI focal instrument AMBER have shown the importance of the differential and closure phase measures, which are supposed to be much less sensitive to atmospheric and instrumental biases than the absolute visibility. However there are artifacts limiting the accuracy of these measures which can be...

We present high spatial resolution observations of the mid-infrared core of the dusty symbiotic system HM Sge. The MIDI interferometer was used with the VLT UTs and ATs providing baselines oriented from PA=42° to 105°. The MIDI visibilities are compared with the ones predicted in the frame of various spherical dust shells published in the...

The amdlib AMBER data reduction software is meant to produce AMBER data products from the raw data files that are sent to the PIs of different proposals or that can be found in the ESO data archive. The way defined by ESO to calibrate the data is to calibrate one science data file with a calibration one, observed as close in time as possible....

The color-differential astrometry method consists in measuring the variations of the photocenter position with wavelength. This yields spectral information on the spatial structure of an unresolved source, and could allow, among other applications, the direct detection and spectroscopy of extrasolar planets. We give some estimates of...

We present the current performances of the AMBER / VLTI instrument in terms of differential observables (differential phase and differential visibility) and show that we are already able to reach a sufficient precision for very low mass companions spectroscopy and mass characterization. We perform some extrapolations with the knowledge of the...

Astronomical optical interferometers sample the Fourier transform of the intensity distribution of a source at the observation wavelength. Because of rapid perturbations caused by atmospheric turbulence, the phases of the complex Fourier samples (visibilities) cannot be directly exploited. Consequently, specific image reconstruction methods...

This paper presents an extension of the spatio-spectral (" 3D ") image reconstruction algorithm called PAINTER (Polychromatic opticAl INTErferometric Reconstruction software). The algorithm is able to solve large scale problems and relies on an iterative process, which alternates estimation of polychromatic images and of complex visibilities....

We present the results of the fifth Interferometric Imaging Beauty Contest. The contest consists in blind imaging of test data sets derived from model sources and distributed in the OIFITS format. Two scenarios of imaging with CHARA/MIRC-6T were offered for reconstruction: imaging a T Tauri disc and imaging a spotted red supergiant. There were...

We present here the current performances of the AMBER / VLTI instrument for standard use and compare these with the offered modes of the instrument. We show that the instrument is able to reach its specified precision only for medium and high spectral resolution modes, differential observables and bright objects. For absolute observables, the...

Aims. We aim to study the geometry and kinematics of the disk around the Be star $\alpha$ Arae as a function of wavelength, especially across the Br$\gamma$ emission line. The main purpose of this paper is to answer the question about the nature of the disk rotation around Be stars. Methods. We use the VLTI/AMBER instrument operating in the K...

LITpro is a software for fitting models on data obtained from various stellar optical interferometers, like the VLTI. As a baseline, for modeling the object, it provides a set of elementary geometrical and center-to-limb darkening functions, all combinable together. But it is also designed to make very easy the implementation of more specific...

This paper presents a study of the atmospheric refraction and its effect on the light coupling efficiency in an instrument using single-mode optical fibers. We show the analytical approach which allowed us to assess the need to correct the refraction in J- and H-bands while observing with an 8-m Unit Telescope. We then developed numerical...