Determination of highly precise proper motions for 32 Hipparcos stars from photographic plates.

Abstract

The authors have reduced 70 exposures on 32 photographic plates taken in four areas of the sky around the radio source 0316+413, the galaxy NGC 7302, the Pleiades astrometric standard region, and so on with the 40-cm astrographic refractor at SheShan (Zô-Sé) Station of the Shanghai Observatory. Using the PPM catalogue as the initial reference catalogue and the central overlapping method with the iteration process, the authors have obtained highly precise positions and proper motions for 32 Hipparcos stars. Due to the large epoch differences (up to 86 years), the mean internal consistencies of proper motions for 32 stars are 0.59 mas/yr and 0.53 mas/yr in right ascension and declination, while those of positions are 23 mas and 18 mas, respectively. The comparisons between the authors' results and those of other catalogues were made.