Galactic Bulge Microlensing Events with Clump Giants as Sources

Abstract

We present preliminary results of the analysis of 5 years of MACHO data on the Galactic bulge microlensing events with clump giants as sources. In particular, we discuss: 1) the selection of `giant' events, 2) distribution of impact parameters, 3) distribution of event durations, 4) the concentration of long duration events in MACHO field 104 centered on (l,b) = (3.1,-3.0). We report the preliminary average optical depth of (2.0 +/- 0.4) x 10^{-6} (internal) at (l,b) = (3.9,-3.8). We discuss future work and prospects for building a coherent model of the Galaxy.

8 pages, 4 figures. To appear in ``Microlensing 2000: A New Era of Microlensing Astrophysics,'' an ASP conference proceedings, eds. J.W. Menzies and P.D. Sackett