proper motion
4.ABSOLUTE PROPER MOTION OF GLOBULAR CLUSTER NGC 4147 ON HIPPARCOS SYSTEM
8.Comparing the PPM and ACRS proper motions, which are constructed on the FK5 system, with those of the Hipparcos, an interiorly nonrigid rotation existing in the FK5 proper-motion system is detected.
10.Proper-motion differences between the FK5 and Hipparcos systems cannot be explained by the constant of the FK5 precessional correction, which is given by the VLBI and LLR observations.

