The Milky Way's Globular Clusters and Streams in 3D Velocity Space: Deciphering Accretion and Constraining the Galactic Potential, Dana Casetti (Yale University)

Recent results from ground-based astrometric programs that encompass large areas of the sky provide the necessary additional two velocity components that are typically lacking in kinematical descriptions of the Milky-Way globular-cluster system and of the numerous streams and overdensities recently identified in the halo. I will describe two proper-motion programs that have substantially 

improved this situation and present their major results. The first of these involves the kinematics of the most massive globular clusters of the Milky Way, which also have very extended, blue horizontal branches (EHB clusters), including the peculiar clusters NGC 6388 and NGC 6441. The kinematics of the EHB system will be compared with predictions from recent models of the formation of the globular cluster system in a hierarchical cosmology. The second result involves the Sagittarius trailing tidal stream which, due to the geometry of the orbit of Sagittarius, is an excellent tool for the determination of the rotation of the Local Standard of Rest. A preliminary rotation value, obtained in this manner, is presented.