Abstract The Chinese Space Station Telescope (CSST) presents significant potential for high-precision astrometry. In this study, we show that the point spread function (PSF) modelled by the discrete PSF with Gaussion-mixed function can effectively enhance the astrometric accuracy. We determine that the PSF profile can be accurately modelled by three Gaussians, which take advantage of reducing computational complexity in PSF convolution. We demonstrate that the precision of our position measurements for stars fainter than 21 mag in the simulated CSST crowded field is better than the results from both SExtractor and DOLPHOT. We find that the proper motion errors remain below 1.0 mas/yr for point sources with five observations and approximately 0.8 mas/yr for seven observations with a time base-line of around 3.5 years. Using CSST Main Survey simulation data across different bands and historical data from the Hubble Space Telescope (HST), we estimate that the systematic proper motion precision for M31 can reach 1 μas/yr.
Nie et al. (Tue,) studied this question.
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