Absolute Proper Motion of the Sagittarius Dwarf Galaxy and of the Outer Regions of the Milky Way Bulge

Abstract

We have determined the absolute proper motion of the Sagittarius dwarf spheroidal galaxy (Sgr) from the Southern Proper Motion Catalog 3, by selecting red giant candidates from the Two Micron All Sky Survey. We obtain μlcosb=-2.35+/-0.20 and μb=2.07+/-0.20 mas yr-1. Using the same procedure, we also determine the absolute proper motion of the bulge in the region of the sky that overlaps with Sgr. For the bulge, we obtain μlcosb=-5.86+/-0.14 and μb=-0.59+/-0.14 mas yr-1, at l=7.6d and b=-21.2d. The absolute proper motions are on the International Celestial Reference System via Hipparcos Catalog stars.