Second Cape Photographic Catalogue 1950.0 - I. Provisional catalogue of positions of stars in the Cape Zone, -40 to -52

The Second Cape Photographic Catalogue 1950.0 (CPC2) will be formed from measurements made on 5820 plates, covering the whole southern hemisphere, which were taken at the Cape between 1962 and 1972, and measured on the GALAXY machine at Herstmonceux. The definitive catalogue positions will be derived by a block adjustment of the whole plate series. As a first approximation, provisional positions are obtained by classical methods. The present catalogue, which is printed in microfiche and is also available on magnetic tape, contains the provisional positions for 51 018 stars in the Cape zone, −40° to −52°, on the FK4 system. From plate-to-plate comparisons, the internal mean error of a single coordinate obtained from the mean of four plates is estimated to be rather less than $$\pm 0^"_. 1$$ at the mean epoch of observation, around 1962; the systematic deviation from the FK4 system in a small area is probably also about $$\pm 0^"_. 1$$. New proper motions have been determined for 22 731 stars which are also in the Smithsonian Astrophysical Observatory (SAO) catalogue; the formal mean error of an annual proper motion in each coordinate is about $$\pm 0^"_. 004$$.