Perspective Secular Changes in Proper Motion, Radial Velocity, and Parallax

Abstract

As time goes by, and stellar paths cover longer time intervals, it becomes necessary in astrometric studies to take into account the perspective secular change in proper motion, which is proportional to the radial velocity V, the (absolute) proper motion μ, and the (absolute) parallax p. Of less immediate concern are the corresponding changes in radial velocity, parallax and apparent magnitude, not to speak of the secular changes in these secular changes.