上海天文台1.56米望远镜#1 CCD照相机的测光性能变化

Photometric Property Variation of the #1 CCD Camera of the 1.56 m Reflector of Shanghai Astronomical Observatory

上海天文台1．56米望远镜的#1CCD照相机，在2002年安装时一切正常。之后的十多年间，CCD芯片没变，但控制系统几经维修，其测光性能也几度变化。2004年开始，I波段测光性能发生奇怪退变，CCD上若干小区域的灵敏度下降约3％，并且呈现小的非线性（平场改正无效）。但此现象仅限于I波段，亦即仅涉及近红外光，B，V，R波段均未发现异常。大约在2009-2011年所拍摄的CCD资料，其测光结果呈现严重非线性。何时发生此类严重非线性现象，需要对拍摄的所有CCD资料检测才能确定。2013年对控制系统进行维修后，测光性能基本恢复正常。1．56米望远镜曾经是中国国家天文光学开放实验室的一部分。现在该望远镜的所有观测数据已进入中国虚拟天文台，按有关规定，其所有的CCD天文观测资料对整个天文界开放使用。未来潜在用户需要注意其性能变化，以免被误导。

The #1 CCD camera attached to the 1.56 m reflector of Shanghai Astronomical Observatory was in normal use since 2002. The camera has been repaired for several times during the more than 10 years, so its photometric property has been varied several times either. It has suffered from a kind of strange deterioration since 2004. There are some local subregions on the CCD chip where the sensitivity has decreased about 3% and non-linearity photometric results appeared. The number of these local subregions has increased since 2004. But the deterioration only appears in I band, not in B, V or R band. That is to say, only the near-infrared photons are involved. However, it has been found that severe non-linearity appears in the observed data between 2009 and 2011. In addition, the results measured by aperture photometry is very much different from that of the psf analysing methods. All the data obtained so far should be checked to determine when the non-linearity began to happen. After the camera has been repaired again in 2013, the photometric property almost returns to normal.