Comparison of the astrometric precision of a single measurement by Gaia and CSST. The astrometric precision in the R.A. and decl. directions are shown with different colors. The horizontal axis is either the Gaia G band or the CSST g band. Gaia position uncertainties are derived from equations (1)–(4) in M. Perryman et al. (2014) and Equation (7) in Gaia Collaboration et al. (2016), while CSST position uncertainties are obtained from Figure 4 in Z.-S. Fu et al. (2023).