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Last name: ARISTIDI
First name: E.
This paper presents some statistical information about the Concordia turbulent surface inversion layer, regarding height and turbulent energy, its contribution to the peculiar local seeing, and the free atmosphere seeing encountered just above this surface layer.
This paper gives an introduction to the theory of orthogonal projection of functions or signals. Several kinds of decomposition are explored: Fourier, Fourier-Legendre, Fourier-Bessel series for 1D signals, and Spherical Harmonic series for 2D signals. We show how physical conditions and/or geometry can guide the choice of the base of functions...
We present long term site testing statistics obtained at Dome C, Antarctica with various experiments deployed within the Astroconcordia programme since 2003. We give values of integrated turbulence parameters in the visible at ground level and above the surface layer, vertical profiles of the structure constant C_n^2 and a statistics of the...
On the Antarctica plateau, a joint project of french and italian polar programmes in just near completion: the Concordia station will be open for winterover operation in 2005. The high altitude and high latitude of this site, the exceptionally cold, clear and stable atmosphere, the almost indefinitely flat snow surface and the not so difficult...
This paper presents numerical illustrations of the effects of clipping of photoevents in speckle interferometry and speckle masking. The clipping is due to a saturation of the photon-counting detectors that cannot count more than one photon per pixel, causing the image to be composed of "0" and "1". The theoretical basis for this study has been...
Context. The winter seeing at Concordia is bimodal, i.e. either excellent or quite poor, depending on the altitude above the snow surface. We study the temporal behavior of the good seeing sequences. Efficient exploitation of extremely good seeing conditions with an adaptive optics system requires long integrations.Aims: We examine the temporal...
International audience
We present a reanalysis of several years of DIMM data at the site of Dome C, Antarctica, to provide measurements of the coherence time τ 0. Statistics and seasonal behaviour of τ 0 are given at two heights above the ground, 3m and 8m, for the wavelength λ = 500nm. We found an annual median value of 2.9ms at the height of 8m. A few measurements...
We report in this communication the rst experimental results in the visible range obtained by the Probability Imaging technique applied to close binary stars. Speckle data of the well known binary Del as well as the newly discovered one Moai1 (Carbillet et al. 1996) are processed. An analysis of the probability density functions, combined with...
The optical turbulence forecasting has become a necessary information for an optimal programmation of the astronomical observations, called "flexible scheduling". We propose the prediction of the optical turbulence by means of the Weather Research and Forecasting (WRF) model combined with an optical turbulence model. We performed a set of...
This paper describes a method of beam-combination in the so-called hypertelescope imaging technique recently introduced by Labeyrie in optical interferometry. The method we propose is an alternative to the Michelson pupil reconfiguration that suffers from the loss of the classical object-image convolution relation. From elementary theory of...
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International audience
We present an interferometric beam recombination technique which allows achromatic and direct true imaging of targets at very high angular resolution. This technique intrinsically overcomes the main problems of Labeyrie's hypertelescope design, and can be used in a nulling configuration. It is thus particularly well suited for high contrast...
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Context. For detecting and directly imaging exoplanets, coronagraphic methods are mandatory when the intensity ratio between a star and its orbiting planet can be as large as 10 6. In 1996, a concept of an achromatic interfero-coronagraph (AIC) was presented for detecting very faint stellar companions, such as exoplanets. Aims. We present a...
To reach a high performance with an adaptive optics system, we need a calibration using a reference source. This latter should be located in the same isoplanatic domain as the science source. Different techniques and methods have been developed leading to estimations of the isoplanatic patch but all are model-dependent. We developed a new...
SF2A-2003: Semaine de l'Astrophysique Française, eds. F. Combes, D. Barret and T. Contini, n/a, p. 157 (2004)
This paper describes a method of beam-combination in the so-called hypertelescope imaging technique recently introduced by Labeyrie in optical interferometry. The method we propose is an alternative to the Michelson pupil reconfiguration that suffers from the loss of the classical object-image convolution relation. From elementary theory of...
International audience
International audience
We present in this paper a technique for imaging binary stars from speckle data. This technique is based upon the computation of the cross-correlation between the speckle frames and their square. This may be considered as a simple, easy to implement, complementary computation to the autocorrelation function of Labeyrie's technique for a rapid...
n/a, Società Astronomica Italiana Publication 2, p. 146 (2003)
Antarctic Science, 18, pp. 437-444 (2006)
The first astronomical seeing monitoring has been made with a DIMM instrument at the Antarctic plateau site of Dome C in December, 2002 on the bright star Canopus (alpha Eri) during the daytime. In these far from optimal conditions, a median seeing of 1.2 arcsec as been obtained, with extended periods better than 1 arc-sec and 12 percent of the...