Analysis of the Gaia Data Release 3 parallax bias in the Galactic plane

Abstract

Context. Systematic errors are inevitable in Gaia published astrometric data. A global recipe has been proposed to correct for the GEDR3 parallax zero-point offset, but this does not take the Galactic plane into consideration. The applicability of their correction model to the Galactic plane remains uncertain. Aims. We attempt to carry out an independent investigation into the sample dependence of the proposed correction, and its applicability to the Galactic plane. Methods. We collected various samples, including quasars, binaries, and sources with parallaxes from other surveys or methods, to validate the proposed correction, especially in the Galactic plane. Results. We conclude that the proposed correction exhibits sample dependence, and does not apply effectively to the Galactic plane. We present a new parallax bias correction for application to the Galactic plane, offering improvements over the previous correction. The correction difference between L21 and this work can be as high as 10 µas within certain ranges of magnitude and colour. This work provides an additional recipe for users of Gaia parallaxes, especially for sources located near the Galactic plane.