CCD Meridian Circle Reductions using TYCHO Positions as Reference

A first CCD 512x512 camera working in scan mode (declination field 14 arcmin) has been tested during 9 months on the Bordeaux automatic meridian circle, then mounted on the Sao Paulo meridian instrument. A second improved camera, with a larger field (28 arcmin), was installed at Bordeaux in June 1996. Using as reference final positions of the Tycho stars provided by the Tycho Consortium for 16 test fields, and the corresponding Starnet proper motions obtained by S. Roser (ARI, Heidelberg), the accuracy of the positions obtained with both Bordeaux and Sao Paulo cameras was found to be about 0.05 arcsec for a star measured at least four times in the range 9-15 mag. The Bordeaux and Sao Paulo instruments are currently used for observations of selected fields (around quasars, open clusters, Solar System objects). As a long-term programme, Bordeaux is starting CCD observations of the Bordeaux Astrographic Catalogue zone (+11 degrees to +17 degrees) and the measurement of the old Bordeaux Carte du Ciel plates in order to derive accurate proper motions in this zone up to V = 15 mag.