Deep Canada-France-Hawaii Telescope photometric survey of the entire M33 galaxy - I. Catalogue of 36000 variable point sources

We have conducted a variability survey of the Local Group galaxy M33, using g',r', and i' observations from 27 nights spanning 17 months, made with the MegaPrime/MegaCam instrument on the 3.6-m Canada-France-Hawaii Telescope (CFHT). We identify more than 36000 variable sources with g', r', i' <~ 24, out of approximately two million point sources in a 1-deg² field of view. This increases the number of known variables in this galaxy by more than a factor of 20. In this paper, we provide a brief description of the data and a general overview of the variable star population which includes more than 1300 candidate variable blue and red supergiant stars, more than 2000 Cepheids, and more than 19000 long-period variable asymptotic giant branch and red giant branch stars.

Based on observations obtained with the MegaPrime/MegaCam, a joint project of Canada-France-Hawaii Telescope (CFHT) and CEA/DAPNIA, at the CFHT which is operated by the National Research Council (NRC) of Canada, the Institut National des Science de l'Univers of the Centre National de la Recherche Scientifique (CNRS) of France, and the University of Hawaii.

E-mail: jhartman@cfa.harvard.edu (JDH); dfb@astro.livjm.ac.uk (DB); kstanek@astronomy.ohio-state.edu (KZS); beaulieu@iap.fr (J-PB); jka@camk.edu.pl (JK); marquette@iap.fr (J-BM); Peter.Stetson@nrc.ca (PBS); alex@camk.edu.pl (AS-C)