Volume 371, Number 1, May III 2001
|Page(s)||366 - 377|
|Section||Numerical methods and codes|
|Published online||15 May 2001|
SCIDAR measurements at Pic du Midi*
UMR 5572 d'Astrophysique, Observatoire Midi-Pyrénées -Centre National de la Recherche Scientifique, 14 avenue Édouard Belin, 31400 Toulouse, France
2 Observatoire de Bordeaux, BP 89, 33270 Floirac, France e-mail: firstname.lastname@example.org
3 Instituto de Astronomía UNAM, Campus Morelia, A.P. 72-3 (Xangari), 58089 Morelia Michoacán, México e-mail: email@example.com
Corresponding author: J.-L. Prieur, firstname.lastname@example.org
Accepted: 14 February 2001
We present SCIDAR measurements made at the Pic du Midi Observatory with PISCO. A series of vertical profiles of the refractive-index structure constant was obtained with the observations of the binary stars γ Del and γ Ari, with 30 second time sampling. In the free atmosphere, the turbulence was dominated by the contribution of a few well-separated atmospheric layers at altitudes in the range 8-20 km, with significant changes within a few minutes. We describe a new method based on the CLEAN algorithm applied on the 2-D covariance function of the irradiance fluctuations in the pupil plane and compare it with the widely-used Maximum Entropy Method applied on a slice of this 2-D function. Our method is much less sensitive to the noise. Vertical profiles of the wind velocity and direction were obtained with an automatic procedure working on the mean cross-correlation function of consecutive frames. Furthermore, we validate a model for the SCIDAR detectivity threshold in terms of distance to the turbulent layers.
Key words: atmospheric effects / site testing / turbulence / methods: data analysis / techniques: image processing
© ESO, 2001
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.