Gaia Data Release 3: The Gaia Andromeda Photometric Survey

TL;DR

Gaia DR3's epoch photometry for 1.2 million sources around M31 enables detailed variability studies and improves data interpretation, paving the way for future Gaia data releases and broader sky analysis.

Contribution

This paper describes the Gaia Andromeda Photometric Survey, including data quality, error correction methods, and variability detection techniques, which are novel for Gaia DR3.

Findings

High-quality epoch photometry for M31 sources.

Effective error renormalization method implemented.

Identification of variable stars unaffected by systematic effects.

Abstract

Context. As part of Gaia Data Release 3 (Gaia DR3), epoch photometry has been released for 1.2 million sources centred on M31. This is a taster for Gaia Data Release 4 where all the epoch photometry will be released. Aims. In this paper the content of the Gaia Andromeda Photometric Survey is described, including statistics to assess the quality of the data. Known issues with the photometry are also outlined. Methods. Methods are given to improve interpretation of the photometry, in particular, a method for error renormalization. Also, use of correlations between the three photometric passbands allows clearer identification of variables that is not affected by false detections caused by systematic effects. Results. The Gaia Andromeda Photometric Survey presents a unique opportunity to look at Gaia epoch photometry that has not been preselected due to variability. This allows investigations to be carried out that can be applied to the rest of the sky using the mean source results. Additionally scientific studies of variability can be carried out on M31 and the Milky Way in general.