Stellar Proper Motion Study of Crowded Stellar Field of CSST

Abstract

The stellar absolute proper motion of crowded field is an important problem of astrometry. The space-based observation could get high spatially revolved images in the crowded field. The China Space Station Telescope (CSST) can provide high precision absolute proper motion that significantly improve the performance of HST and Gaia in the sky area and deepness of observation. The Galactic bulge, as it is of importance in galactic science and is difficult to process, was selected as a sample of the high-density area to test our method and CSST observation erformances. We simulated the CSST observed image and implement our test on it. Two centering methods are conducted, and the precision of centering is about 0.03 to 0.08 pixels depending on the magnitude. The absolute proper motion was measured under different observation strategies in the 10 a baseline. After comparison, we find that equal interval observation is the best choice. We then conclude that six observations can obtain the precision of proper motion is better than 0.2 mas/a between 18 ~ 24 mag. Finally, we estimate the effect of parallax in the proper motion estimation under the different time baselines and stellar velocities.