  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.
