Gaia Data Release 3

The Gaia Andromeda Photometric Survey

¹ Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge, CB3 0HA, UK
e-mail: dwe@ast.cam.ac.uk
² Department of Astronomy, University of Geneva, Chemin Pegasi 51, 1290 Versoix, Switzerland
³ INAF – Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, Via Piero Gobetti 93/3, 40129 Bologna, Italy
⁴ Department of Astronomy, University of Geneva, Chemin d’Ecogia 16, 1290 Versoix, Switzerland
⁵ Dipartimento di Fisica e Astronomia “Ettore Majorana”, Università di Catania, Via S. Sofia 64, 95123 Catania, Italy
⁶ INAF – Osservatorio Astrofisico di Catania, Via S. Sofia 78, 95123 Catania, Italy
⁷ Sednai Sàrl, Geneva, Switzerland
⁸ Ruđer Bošković Institute, Bijenička cesta 54, 10000 Zagreb, Croatia

Received: 7 June 2022
Accepted: 24 June 2022

Abstract

Context. As part of Gaia Data Release 3 (Gaia DR3), epoch photometry has been released for 1.2 million sources centred on M 31. 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 (GAPS) 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 renormalisation. Also, use of correlations between the three photometric passbands allows clearer identification of variables, and is not affected by false detections caused by systematic effects.

Results. GAPS presents a unique opportunity to look at Gaia epoch photometry that has not been preselected based on 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 M 31 and the Milky Way in general.