Abstract
Context. This work is part of a program of proper motion measurements in the Bordeaux Carte du Ciel zone. Aims. We present the CdC2000 catalogue issued from the reduction of the complete Bordeaux Carte du Ciel zone observed at the begining of last century with the Bordeaux astrograph. Methods. Plates have been individually reduced using the TYCHO-2 Catalogue as the astrometric reference. Results. This catalogue is a positional catalogue of 344 781 stars covering the declination zone +11 +18 . The average epoch of positions is 1914.7. The data are from the 512 Carte du Ciel plates archived at the Bordeaux Observatory and scanned with the APM Cambridge automatic measuring machine.Astrometric standard errors are about 0.10 00 to 0.12 00 on positions and 0.6 magnitudes on photographic magnitudes. Conclusions.A detailed study of errors and a comparison of various reduction methods are presented in order to take into account the significant propagated errors from the reference catalogue. The CdC2000 provides positions at the epoch of the plates for 50 682 TYCHO-2 stars. The associated positions are proved to be p 2 more precise than the positions given by the TYCHO-2 catalogue at the epoch of the plates (0.11 00 instead of 0.15 00 ). This work is part of a program of proper motion measurements in the Bordeaux Carte du Ciel zone.
Highlights
Accurate proper motions for a large set of stars are of great importance to many areas of astronomy, in particular for galactic studies
The CdC2000 catalogue is the first complete reduction of a Carte du Ciel zone and provides a precious ancient positional data set for proper motion measurements
We reduced all the plates with the tycho-2 reference catalogue using a 12 constants model and we compared the calculated position of the tycho-2 stars with their catalogue positions
Summary
Accurate proper motions for a large set of stars are of great importance to many areas of astronomy, in particular for galactic studies. The precise determination of proper motions relies heavily on the time base between the various catalogues compared In this magnitude domain there is no all-sky astrometric catalogue with ancient positions such as AC2000.2. While the Astrographic program was completed and published (at the epoch in each observatory and later in AC2000.2 (Urban et al 2001)) the Carte du Ciel project never led to the publication of a catalogue. The idea was to re-observe this zone with the Bordeaux automatic CCD meridian circle (Rapaport et al 2001) and to simultaneously measure the Bordeaux Carte du Ciel plates at the APM (Cambridge). The CdC2000 catalogue is the first complete reduction of a Carte du Ciel zone and provides a precious ancient positional data set for proper motion measurements.
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