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。

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.

A flat field calibration is automatically applied to all CCD Images that are loaded thereafter.

此后载入的所有CCD图片将针对此平场图片做校正.