For astrometric purposes , dark frame and flat field calibration is recommended 出于天文测量要求，暗场图和平场图校准是被推荐的。
3.
Astrometric limit : the maximum residual in the place of a reference star , specified in arc seconds 天文测量误差极限：参考星位置对应的最大误差，用角秒表示。
4.
In this section , you can set a limit to the astrometric and photometric residuals of the reference stars 在这里，你可以设置一个有关参考星的天文测量和光度测量的误差值。
5.
Any reference star that if found to show larger residual in either right ascension or declination will be rejected from the astrometric solution 任何一个参考星的赤经或赤纬偏差超过这个值将被拒绝进行天文测量处理。
6.
Further image processing ( e . g . , histogram scaling , application of filters or deconvolution ) is not recommended for astrometric or photometric applications , because it will distort the centroids and flux of the objects in the image 其他的操作（如：柱状图缩放，滤镜处理或去卷积）在天文测量或光度测量软件中将不被推荐，因为这样的操作会对目标星的光流量和聚焦中心产生误差。
7.
And then , according to the kind of satellite and the requirements for geodetic and astrometric study and the geometry of gnss ( gps , galileo ) satellite to track the space vlbi satellite , the six keplerian elements of chinese space vlbi satellite ( test - svlbi ) are selected and determined 根据卫星轨道的分类、大地测量和天体测量对空间vlbi卫星的要求,以及gnss ( gps和galileo )卫星对空间vlbi卫星跟踪观测的几何条件而设计了我国空间vlbi卫星的六个轨道根数。
