PAndromeda—First Results from the High-cadence Monitoring of M31 with Pan-STARRS 1

The Pan-STARRS 1 (PS1) survey of M31 (PAndromeda) is designed to identify gravitational microlensing events, caused by bulge and disk stars (self-lensing) and by compact matter in the halos of M31 and the Milky Way (halo lensing or lensing by massive compact halo objects). With the 7 deg(2) field of view (FOV) of PS1, the entire disk of M31 can be imaged with one single pointing. Our aim is to monitor M31 with this wide FOV with daily sampling (20 minutes day(-1)). In the 2010 season, we acquired in total 91 nights toward M31, with 90 nights in the r(P1) and 66 nights in the i(P1). The total integration time in r(P1) and i(P1) are 70,740 s and 36,180 s, respectively. As a preliminary analysis, we study a 40' x 40' sub-field in the central region of M31, a 20' x 20' sub-field in the disk of M31, and a 20' x 20' sub-field for the investigation of astrometric precision. We demonstrate that the point-spread function is good enough to detect microlensing events. We present light curves for six candidate microlensing events. This is a competitive rate compared with previous M31 microlensing surveys. Finally, we also present one example light curve for Cepheids, novae, and eclipsing binaries in these sub-fields.