Involved people at OAB: Bellazzini, Cacciari, Federici, Fusi Pecci, Marano.
A wide photometric survey sampling the disc and the halo of the M31 toward 16
different lines of sight has been recently started, using the WFPC2 observations
that had the M31 globulars as primary target. A fully automated pipeline has
been developed for the data reduction and a final sample of 470704 M31 stars
with accurate V,I measures down to 
has been obtained. The analysis is
currently in progress and a first paper is in preparation.
We have also undertaken the study of a peculiar object in M31, identified during a search for globular clusters. This 21st mag. object is possibly extended and is the optical counterpart of a radio and X-ray source. Most likely the object is either a very young, peculiar SNR in M31, or a background AGN, strongly absorbed through the disk of M31. In any case the source is an interesting ``test particle'' for studying M31 properties. Very high-resolution UBVRI images taken with TNG/OIG in November 1999 show a double-peaked image, with a blue and a red component. Low resolution spectra are necessary to clarify the nature of the object, and are planned for the next available opportunity.