摘要
传统的运动学天球参考架的建立均以赤道和黄道的定义以及对它们的运动的描述(即岁差与章动表达式)为基础.因此,这些定义和表达式中每一项变化均要求参考架作相应变化.另外,岁差章动表达式的误差将引起参考架的畸变.而用河外天体的方向定义坐标系,并参考于该坐标系建立一个参考架,这样的参考架可避免上述的传统的参考架的缺陷.本文讨论了关于这种参考架的定义,实现和应用等问题,并建议用这样的参考架取代目前以地球的动力学平面有关的参考架(如FK5和现有的河外射电源表).
Up to now, all the Conventional Celestial Reference Frames (CCRF), such as FK5 as well as available radio source catalogues, are traditionally based on the conceptions of the equator, ecliptic, precession and nutation. Therefore, any changes in the expressions of precession or nutation as well as in the definitions of the equator or ecliptic must require a reconstruction of the CCRF. Such work is so heavy and complicated that it cannot be done strictly. In addition, the errors in the expressions of precession or nutation may cause some distortion of CCRF. In principle, a celestial coordinate triad can be defined by an arbitrary group of objects (stars or radio sources). Referring to it, a Directly Defined Celestial Reference Frame (DCRF) can be constructed. In this paper, we prove that the DCRF can 'be realized by means of ground-based techniques such as VLBI, meridian circle and so on, as well as the HIPPARCOS astrometry satellite. The DCRF can be applied to astrometry and geodesy. Such a frame is uniform and permanent. Therefore, we suggest that the traditional CCRF should be eplaced by the DCRF.
出处
《天文学报》
CSCD
北大核心
1991年第3期297-303,共7页
Acta Astronomica Sinica
关键词
天球参考架
测定
分点
岁差
Celestial Reference Frame—Absolute Determination—Equinox and precession
