A comparison of ground-based stellar positions and proper motions with provisional HIPPARCOS results
Preliminary positions and proper motions derived from the first 30 months of the Hipparcos mission are compared with some of the best ground-based catalogues and optical measurements. Comparison with FK5 and PPM very clearly brings out the zonal and regional errors of these catalogues. The proper motion system of PPM is found to have magnitude dependent errors which are reflected in the PPM positions at the current epoch. A comparison of Hipparcos data with positions from the USNO Mark III optical interferometer shows excellent agreement at the expected accuracy level of the interferometer (0.02arcsec). The results of all the comparisons are consistent with the predicted high quality of the Hipparcos reference system, although none of the ground-based optical measurements are accurate enough to present a real challenge to the space results.
Astronomy and Astrophysics
- Pub Date:
- December 1995