1988年至1995年IERS天球参考架的指向维持

本文分析了１９９２年至１９９５年期间国际地球自转服务（ＩＥＲＳ）天球参考架的指向维持情况，结合１９８８年至１９９２年的指向维持情况指出，该参考架在１９８８年至１９９５年期间历年的指向均存在显著变化，赤经零点和天极的最大年度漂移约为０．４ｍａｓ。至１９９５年，ＩＥＲＳ天球参考架的赤经零点和天极与各自预期位置的偏差不于０．４ｍａｓ。１９９４年和１９９５年的ＩＥＲＳ天球参考架基本上维持了１９９３年的ＩＥＲＳ天球参考指向，但是其实际维持精度约为０．０５ｍａｓ，并非０．００５ｍａｓ。０．００５ｍａｓ的维持精度只是数学上的平均效果，相当一部分基本源在相邻年度的ＩＥＲＳ天球参考架中的坐标差大于０．５ｍａｓ，这说明只有采用恰当的消除局部相对形变的方法，才能将天球参考架的指向真正维持在较高水平。

The Maintenance of the Orientation of IERS Celestial Reference Frames from 1988 to 1995

The maintenance of orientation of the international Earth Rotation Service(IERS)celestial reference frames from 1992 to 1995 are analyzed in this paper. In combination with the maintenance for years from 1988 to 1992, it is concluded that there are detectable variations in the orientation of IERS celestial reference frames from 1988 to 1995. The biggest shifts of the origin of right ascension and of the celestial pole are about 0. 4mas. Till 1995, the deviations of the origin of right ascension and the celestial pole from their originally expected positions are no less than 0. 4mas. The orientation of the 1993's IERS frame was maintained by the 1994 and 1995 IERS frames at a precision of 0. 05mas rather than 0. 005mas.The precision of 0. 005mas is a result of mathematical mean. The coordinate differences of a considerable number of primary (or defining)sources in successive IERS frames are bigger than 0. 5mas, which demonstrates that the orientation of the celestial reference frames can be maintained in a relatively high precision if a suitable method for identifying or removing the local relative deformations between individual frames was adopted.