1996A&A...313..841D

During the last three years, several galactic microlensing events towards the Large Magellanic Cloud and the Galactic Bulge have been detected by four observing groups (MACHO, EROS, OGLE, DUO). Most of these are commonly explained as due to microlensing of a point source by a point mass lens. In this paper, we discuss statistical methods to determine the goodness-of-fit for a specific model of source and lens beyond the assumption that the errors are normal. In particular, we argue that the MACHO LMC#1 event has been caused by a binary lens and thereby confirm our hypothesis (Dominik & Hirshfeld 1994). We also show that the binary lens fit is not unique by presenting alternative plausible binary lens fits. We emphasize that knowledge of the fraction of binaries among the observed microlensing events is crucial for estimating the mass distribution of the observed dark objects. We finally show that for each data set of parameters for a binary source, two physical configurations with different distances between the components exist which produce exactly the same light curve.