Parts I and III of the sixth fundamental catalog, a catalog of
high-precision astrometry for bright stars combining centuries of
ground-based observations as reflected in FK5 with HIPPARCOS
astrometry.
The result contains, in particular for the proper motions,
statistically significant improvements of the Hipparcos data und
represents a system of unprecedented accuracy for these 4150
fundamental stars. The typical mean error in pm is 0.35 mas/year for
878 basic stars, and 0.59 mas/year for the sample of the 3272
additional stars.
