1.56m望远镜新CCD相机MPP模式开与关的对比

摘要

The new CCD system at the 1.56m reflector optical telescope of Shanghai Astronomical Observatory (SHAO)was built at the Lick Observatory and uses their control electronics design. This system has the ability to switch between multi-pinned phase (MPP) and normal operation modes. Comparisons between the MPP and normal operation modes have shown that: 1 ) Gain and read-out noise are the same for both modes. 2 ) Working at -100℃ in MPP mode, dark current is negligible for short and moderate exposures, and is insensitive to temperature variations in the CCD chip; while in normal mode dark frames show a pattern which is sensitive to the temperature of the CCD. Thus,a stable cold temperature should be maintained, and in long exposures a dark frame must be subtracted from the object frame. 3) The disadvantage of using MPP is that the dynamic range decreases to ～ 9000adu (for a gain of 4.6e-/adu). It is suggested that users select the mode which best suits their scientific purposes.%1.56m望远镜新CCD系统是在里克天文台用其控制电路组装而成的.该系统能在MPP模式与非MPP模式之间自由快速转换.我们比较了两种模式的性能差异,得到:(1)增益和读出噪音不变.(2)在-100℃温度,MPP模式的暗流对短的或中等长度的露光可以忽略,并且暗流对CCD芯片的温度变化不太敏感;非MPP模式的暗流有确定的图案,对CCD的温度变化比MPP敏感.因此稳定的低温是必须的,并且使用时须减暗流.(3)使用MPP的代价是,相对于非MPP模式,动态范围至少减小约9000adu(增益4.6e-/adu).用户使用时应按照科学目的选择模式.