Probing MACHOs by observation of M 31 pixel lensing with the 1.5 m Loiano telescope

¹ Dipartimento di Fisica “E. R. Caianiello”, Università di Salerno, via S. Allende, 84081 Baronissi (SA), Italy e-mail: novati@sa.infn.it
² Istituto Nazionale di Fisica Nucleare, sezione di Napoli, Italy
³ INAF – Osservatorio Astronomico di Capodimonte, via Moiariello 16, Napoli, Italy
⁴ Dipartimento di Fisica, Università di Lecce and INFN, Sezione di Lecce, CP 193, 73100 Lecce, Italy
⁵ SUPA, University of St Andrews, School of Physics & Astronomy, North Haugh, St Andrews, KY16 9SS, UK
⁶ APC, 10, rue Alice Domon et Léonie Duquet 75205 Paris, France
⁷ Institute for Theoretical Physics, University of Zürich, Winterthurerstrasse 190, 8057 Zürich, Switzerland
⁸ Department of Astronomy, Ohio State University, 140 West 18th Avenue, Columbus, OH 43210, US

Received: 10 January 2007
Accepted: 29 March 2007

Abstract

We analyse a series of pilot observations in order to study microlensing of (unresolved) stars in M 31 with the 1.5 m Loiano telescope, including observations on both identified variable source stars and reported microlensing events. We also look for previously unknown variability and discover a nova. We discuss an observing strategy for an extended campaign with the goal of determining whether MACHOs exist or whether all microlensing events are compatible with lens stars in M 31.