标题： 斯隆数字巡天的天体测量校准 显示英文标题

标题： Astrometric Calibration of the Sloan Digital Sky Survey

摘要： 斯隆数字天空调查的天体测量校准方法被描述。对于r约为20以上的点源，相对于美国海军天文台CCD望远镜星表进行归算时，天体测量精度为每坐标45毫角秒（mas）均方根，而相对于Tycho-2进行归算时为75 mas均方根，两种情况下各存在20-30 mas的系统误差。均方根误差主要由异常折射和主参考星表中的随机误差主导。r滤光片与其他滤光片（u g i z）之间的相对天体测量精度为25-35 mas均方根。在调查极限（r约为22）时，天体测量精度受光子统计限制，典型视宁度下约为100 mas均方根。显示异常折射包含在天空上两个或更多度范围内相关的成分。 显示英文摘要

摘要： The astrometric calibration of the Sloan Digital Sky Survey is described. For point sources brighter than r ~ 20 the astrometric accuracy is 45 milliarcseconds (mas) rms per coordinate when reduced against the USNO CCD Astrograph Catalog, and 75 mas rms when reduced against Tycho-2, with an additional 20 - 30 mas systematic error in both cases. The rms errors are dominated by anomalous refraction and random errors in the primary reference catalogs. The relative astrometric accuracy between the r filter and each of the other filters (u g i z) is 25 - 35 mas rms. At the survey limit (r ~ 22), the astrometric accuracy is limited by photon statistics to approximately 100 mas rms for typical seeing. Anomalous refraction is shown to contain components correlated over two or more degrees on the sky.