Improvement of proper motions for Hipparcos stars with photographic plates.

Abstract

Using the PPM catalogue as a preliminary reference catalogue, the authors have reduced 17 exposures on 9 plates taken with the 40 cm refractor at Zo-Sè Station of Shanghai Astronomical Observatory in about 30 years. By means of the central overlapping technique and the iterative process, high-precision positions and proper motions of 28 PPM stars, including 6 Hipparcos stars in the region of the radio source 0316+413 are obtained. The mean values of the internal standard errors of proper motions in right ascension and declination for the 6 Hipparcos stars are ±0″00069 yr^-1 and ±0″00070 yr^-1, respectively.