LAMOST工程中天体测量要求的探讨

Discusion on Astrometric Requirements in LAMOST Project

作者认为，有五种误差会影响ＬＡＭＯＳＴ工程光纤定位：（１）光纤的机械定位误差；（２）输入星表与导星星表的误差；（３）焦面坐标系与理想坐标系的转换误差；（４）较差大气折射对观测目标的影响；（５）导星的跟踪误差。并提出在ＬＡＭＯＳＴ工程中有关天体测量的三个研究课题：（１）星表系统差的研究，以提供适合ＬＡＭＯＳＴ使用的导星星表和输入星表；（２）望远镜光学系统畸变的研究以及焦面坐标与理想坐标间关系的确定，提出用国内外观测资料，建立５°×５°的几个标准天区；（３）从现有的光学图象和测光资料中给出ＬＡＭＯＳＴ输入星表中星象的类别，如双星、聚星、变星、星系等。建议ＬＡＭＯＳＴ工程中采用ＧＳＣ－Ⅱ作为导星星表，而输入星表的精度应好于０．５４”。

In this paper, the following factors, which cause the positional offset of the optical fiber, are discussed: (1)error on the mechanical positioning of the fiber, (2)error from the transformation between the focal coordinates and standard coordinates, (3)differential atmospheric refraction, (4)errors of position and proper motion in the input catalogue and guiding catalogue, (5)tracking error of telescope. Besides, the authors think the following astrometric subjects should be studied: (1)study the systematic differences of the catalogues and provide the input and guiding catalogues for LAMOST project, (2)examine the distortion of optical system, detemine the relation between focal coordinates and standard coordinates, and establish several standard celestial zones(5°×5°) based on both foreign and domestic observations. (3)give the type of object, such as double star, variable star, multiple star, galaxy and so on , for the input catalogue based on the available observations. At last, the authors recommend GSC-Ⅱ as the guiding catalogue, and point out that the precision of the input catalogue should be better than 0.54'.