Astrometry with the MACHO data archive. I. High proper motion stars towardthe Galactic bulge and Magellanic Clouds

We present the preliminary results of our astrometric study of stellar moti ons along the lines of sight of the Magellanic Clouds and the Galactic bulg e. Using 5 years of MACHO project point-spread function photometry, we find that we can easily select stars with proper motions of 0."03 yr(-1) from t hese very dense fields, using the characteristic shapes of their light curv es. By performing astrometry on photometrically selected, candidate, high p roper motion (HPM) stars in 50 deg(2), we have discovered 154 new HPM stars from similar to 55 million stars monitored by the MACHO project. These new objects have proper motions as high as 0."5 yr(-1), brightnesses ranging f rom V similar to 13 to V similar to 19, and V - R colors between 0.3 and 1. 45.