Reading Precision of the Video CCD in the LLMC and Effect of the Atmospheric Agitation

The reading precision of the video CCD in the LLMC is estimated by using observation data.It is pointed out that the precision of the measured coordinates of the object is low if only one image is used and that the expected requirements in detecting the pointing variation of the optical axis are met with the new method for determining “the tube flexure” and coordinates of many images. According to the measured effect of the atmospheric agitation at the different zenith, we simulate the effect of the atmospheric agitation and the law that the effect changes with zenith.