The Extended Gaia–PS1–SDSS (GPS1+) Proper Motion Catalog

Abstract

Abstract The Gaia + PanSTARRS1 (PS1) + Sloan Digital Sky Survey (SDSS) + Two Micron All-Sky Survey (2MASS) (GPS1) catalog was released in 2017. It delivered precise proper motions for around 350 million sources down to a magnitude of mag. In this study, we present GPS1+, the extension GPS1 catalog down to mag, based on Gaia data release 2 (DR2), PS1, SDSS, and 2MASS astrometry. GPS1+ totally provides proper motions for ∼400 million sources with a characteristic systematic error of less than 0.1 mas yr−1. This catalog is divided into two subsamples, i.e., the primary and secondary parts. The primary ∼264 million sources have either or both Gaia and SDSS astrometry, with a typical precision of 2.0–5.0 mas yr−1. In this part, ∼160 million sources have Gaia proper motions, and we provide another new proper motion for each of them by building a Bayesian model. Relative to Gaia's values, the precision is improved by ∼0.1 dex on average; ∼50 million sources are the objects whose proper motions are missing in Gaia DR2, and we provide their proper motions with a precision of ∼4.5 mas yr−1. The remaining ∼54 million faint sources are beyond Gaia detecting capability, and we provide their proper motions for the first time with a precision of 7.0 mas yr−1. However, the secondary ∼136 million sources only have PS1 astrometry, where the average precision is worse than 15.0 mas yr−1. The large uncertainty probably limits it to qualitative applications. All the proper motions have been validated using QSOs and the existing Gaia proper motions. The catalog will be available via the TAP Service in the German Astrophysical Virtual Observatory.