next previous
Up: Abstract

A&A Supplement series, Vol. 128, March II 1998, 621-630

Received May 20; accepted August 4, 1997

A new approach to the reduction of "Carte du Ciel'' plates

A. Ortiz-Giltex2html_wrap1534,gif - M. Hiesgentex2html_wrap1536 - P. Brosche tex2html_wrap1534

Send offprint request: A. Ortiz-Gil

tex2html_wrap1540  Sternwarte der Universität Bonn, Auf dem Hügel 71, D-53121 Bonn, Germany
tex2html_wrap1542  Observatoire de Strasbourg, 11 rue de l'Université, 67000 Strasbourg, France


A new procedure for the reduction of "Carte du Ciel'' plates is presented. A typical "Carte du Ciel'' plate corresponding to the Bordeaux zone has been taken as an example. It shows triple exposures for each object and the modeling of the data has been performed by means of a non-linear least squares fitting of the sum of three bivariate Gaussian distributions. A number of solutions for the problems present in this kind of plates (optical aberrations, adjacency photographic effects, presence of grid lines, emulsion saturation) have been investigated. An internal accuracy of tex2html_wrap_inline1506 in x and y was obtained for the position of each of the individual exposures. The external reduction to a catalogue led to results with an accuracy of tex2html_wrap_inline1512 in x and tex2html_wrap_inline1516 in y for the mean position of the three exposures. A photometric calibration has also been performed and magnitudes were determined with an accuracy of tex2html_wrap_inline1520.

keywords: astrometry -- methods: data analysis -- open cluster: M67

Copyright by the European Southern Observatory (ESO)