从FK4系统到FK5系统的转换  

TRANSFORMATION FROM FK4 SYSTEM TO FK5 SYSTEM

作　　者：黄天衣[1] 夏一飞[1] 

机构地区：[1]南京大学天文系

出　　处：《天文学报》1991年第3期258-267,共10页Acta Astronomica Sinica

基　　金：国家自然科学基金

摘　　要：本文分析了从FK4系统到FK5系统的不同转换方法,讨论了转换时零点改正的应用和历元的选择,给出了变换到J2000.0星位和自行的数值例子.我们认为应选择本文中(5)式的转换方法.In this paper, the different procedures of the transformation from FK4 to FK5 are reviewed, the application of the equinox correction and the selection of the transfer epoch are discussed, and some numerical examples for J2000.0 positions and proper motions are given. We obtained the following results: 1) The largest differences of positions and proper motions at J2000.0 obtained from four procedures of the transformation are: 0~s.0012 for cos δ△α, 0″.011 for △δ, 0~s.0010 pet Julian century for cos δ△μ_α, and 0″.015 per Julian century for △μ_δ. 2) In the transformation from FK4 to FK5 the equinox correction should be applied to he rotating frame theoretically. The effect of the equinox correction on the proper motions should be considered. This point should be noticed when one makes use of proper motions to determine the precession correction. 3) If the transfer from FK4 to FK5 isn't performed at the epoch of B1950.0, the systematic and individual errors due to the precession error and the equinox correction will be caused. They are related with the epoch difference between B1950.0 and transfer epoch. Furthermore, the individual errors depend on the star's velocity. These errors can be omitted for the present precision. Therefore, the transfer from FK4 to FK5 may be performed at any epoch. 4) One of the main reasons of the transfer from FK4 to FK5 at the epoch of 1984 January 1 by Aoki et al. is to consist with the new definition of UT. The effect of the systematic and individual corrections of FK4 stars at the beginning of 1984 on UT cann't be omitted. So the selection of the epoch of the transfer from FK4 to FK5 shouldn't and couldn't consist with the new definition of UT. 5) In the transformation from FK4 to FK5 we prefer to select equation (5) and numerical values of Table 1. That is to say, the transfer is performed at B1950.0 and the equinox correction is applied to the rotating frame.

关 键 词：参考系 FK4系统 FK5系统 星位 变换 

分 类 号：P152[天文地球—天文学]