An empirical model of the Gaia DR3 selection function

Vol. 669
13. Astronomical instrumentation

An empirical model of the Gaia DR3 selection function

The astrometric and photometric main catalog of the Gaia third data release (DR3) has a very complex selection function, which depends on both the detailed scanning history of the satellite and the local source density. This selection has up to now consequently been poorly characterized, which strongly limits the statistical uses of the catalog. Cantat-Gaudin et al. demonstrate, through comparisons with deeper catalogs across parts of the sky, that the DR3 selection function as a function of G magnitude and sky positions is described to within a few percent by an analytical function of a single parameter, the median magnitude at which stars in the local sky patch have fewer than ten well-measured Gaia transits. That parameter is determined entirely from the DR3 catalog itself, and the analytical description is therefore applicable over the whole sky.