E. Masciadri, F. Lascaux, J. J. Fuensalida, -, G. Lombardi, H. Vazquez-Ramio
Generalized Scidar (GS) measurements taken at the Paranal Observatory in
November/December 2007 in the context of a site qualification for the future
European Extremely Large Telescope E-ELT are re-calibrated to overcome the bias
induced on the CN2 profiles by a not correct normalization of the
autocorrelation of the scintillation maps that has been recently identified in
the GS technique. A complete analysis of the GS corrected measurements as well
as of the corrected errors is performed statistically as well as on individual
nights and for each time during all nights. The relative errors of the CN2
profiles can reach up to 60% in some narrow temporal windows and some vertical
slabs, the total seeing up to 12% and the total integrated turbulence J up to
21%. However, the statistic analysis tells us that the absolute errors of the
median values of the total seeing is 0.06 arcsec (relative error 5.6%), for the
boundary seeing 0.05 arcsec (relative error 5.6%) and for the seeing in the
free atmosphere 0.04 arcsec (relative error 9%). We find that, in spite of the
fact that the relative error increases with the height, the boundary and the
free atmosphere seeing contribute in an equivalent way to the error on the
total seeing in absolute terms. Besides, we find that there are no correlations
between the relative errors and the value of the correspondent seeing. The
absolute error of the median value of the isoplanatic angle is 0.13 arcsec
(relative error 6.9%).
View original:
http://arxiv.org/abs/1111.4861
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