Standard errors for PPM and Tycho stars

The connection between the optical reference frame and the radio one constitutes one of the main purposes of the astrometry. The paper is pointing out the contribution of the...

光学参考系与射电参考系之间的关联，是天体测量学（astrometry）的核心研究目标之一。本论文着重阐述了……所做出的贡献。