Double Star CCD Astrometry and Photometry

Abstract About 3000 CCD measurements of double stars have been made in one or both filters V and R on the 1m Jacobus Kapteyn Telescope at La Palma. ∗ The stars form part of the INput CAtalogue (INCA) of the astrometric satellite HIPPARCOS, and require both astrometry and photometry in order to facilitate reduction of the HIPPARCOS measurements. The primary components of the binaries have visual magnitudes between 8m and 12m, and the apparent separations between components range from 0″.5 to 30″. The difference in the separation obtained with the two filters is discussed and illustrated for 2100 systems: the dependence upon separation and magnitude difference between components is clearly and quantitatively shown.