低纬子午环配备科学CCD的初步方案

A Preliminary Plan of a Scientific CCD Attached to the LLMC

根据低纬子午环配备科学ＣＣＤ后仍然能对天体位置作绝对测定的要求，提出了该仪器配备科学ＣＣＤ的初步方案，包括在子午方向和卯酉方向观测时，ＣＣＤ芯片如何跟踪星像，如何将芯片致冷，提高信噪比，既能保持镜筒的平衡，又不破坏观测室内空气的稳定性，如何更准确地测定光轴指向的变化。文中还对一次观测的天区面积作了估计。

According to the requirement of the LLMC that the instrument can still determine absolutely the position of a celestial object after a scientific CCD is attached to the LLMC, a preliminary plan is put forward in this paper. The plan includes the following three parts. Firstly, how does the CCD follows the track of the image of a star when it is observed in the meridian? Secondly, how does the telescope follow the track of the image of a star in the angle of elevation? Lastly, how does the variation of the optical axis of the telescope is determined accurately? Besides, the sky area that can be observed in one CCD exposure at different declination parallels is estimated.