Finding the Brightest Galactic Bulge Microlensing Events with a Small Aperture Telescope and Image Subtraction

Following the suggestion of Gould and Depoy (1998) we investigate the feasibility of studying the brightest microlensing events towards the Galactic bulge using a small aperture (≈10 cm) telescope. We used one of the HAT telescopes to obtain 151 exposures spanning 88 nights in 2005 of an 8°4×8°4 FOV centered on (l,b)=(2.85, -5.00). We reduced the data using image subtraction software. We find that such a search method can effectively contribute to monitoring bright microlensing events, as was advocated. Comparing this search method to the existing ones we find a dedicated bulge photometric survey of this nature would fulfill a significant niche at excellent performance and rather low cost. We obtain matches to 7 microlensing events listed in the 2005 OGLE archives. We find several other light curves whose fits closely resemble microlensing events. Unsurprisingly, many periodic variable stars and miscellaneous variable stars are also detected in our data, and we estimate approximately 50% of these are new discoveries. We conclude by briefly proposing Small Aperture Microlensing Survey, which would monitor the Galactic bulge around the clock to provide dense coverage of the highest magnification microlensing events.