空间参考系自行系统与地面自行系统

针对地面FK5和空间依巴谷自行系统 ,采用银河系运动学分析方法发现 ,即使考虑了岁差改正的影响 ,两种自行系统之间仍存在很大差异。用建立在FK5系统上的PPM和ACRS自行与依巴谷自行比较 ,发现FK5自行系统内部存在非刚性运动 ;同时无法用VLBI及LLR所测定的岁差改正值来解释FK5与依巴谷自行系统的关系。

SPACE-BASED AND GROUND-BASED PROPER-MOTION SYSTEMS

Carrying out a kinematical analysis of the Galaxy for proper-motion systems of the FK5 and Hipparcos, a large difference in proper motions between two systems is found, even if the precessional correction to the FK5 system has been considered. 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. 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.