Abstract
We have developed a methodology for the astrometric measurement of photographic plates making use of a CCD camera. In order to measure a complete 2°x 2° plate a mosaic of 8×8 frames with 50% overlap in both coordinates was taken. The detection and centering of stellar images was performed with SExtractor, and by means of our own software triple exposures were identified. A noticeable radial distortion produced by the optical system was found and corrected. The reduction to celestial coordinates was performed by means of the block-adjustment technique, using Tycho-2 as reference catalog. Differences with Tycho-2 suggest that the errors of CCD-based positions obtained from the CdC plate are between 0. and 0.. Completeness of the catalogs obtained is also discussed.
