Analysis about the precision of correlation tracker in space solar telescope (SST)

Abstract

The first astronomical space telescope of China, the Space Solar Telescope (SST), of which the main optical telescope's diameter is one meter, is now being built in the National Astronomical Observatories, Chinese Academy of Sciences (NAOC). In order to obtain high precision data of solar magnetic field, long time exposure is required. Therefore, the correlation tracker technology is applied to keep the images stable during the long exposure and to ensure a high spatial resolution. In this paper, we will analyze the accuracy of the correlation tracker of SST by simulating the high-resolution ground-based observations. By our analyses, it is found that at the spatial scale of 0.1, an accuracy of about 0.3-pixel can be achieved when using cross-correlation method together with 25-point parabolic fitting. The result is better than using only cross-correlation method. And after the quantification effect being computed, Our preliminary result shows that it will get similar result by using either higher or lower level quantification. That is, precision acquired by using 16bit quantification cannot reach much higher than by 1bit in the SST/CT.