  We report progress on measuring the position of Sgr A* on infrared images,
placing limits on the motion of the central star cluster relative to Sgr A*,
and measuring the proper motionof Sgr A* itself. The position of Sgr A* has
been determined to within 10 mas on infrared images. To this accuracy, the
gravitational source (sensed by stellar orbits) and the radiative source (Sgr
A*) are coincident. Proper motions of four stars measured both in the infrared
and radio indicate that the central star cluster moves with Sgr A* to within 70
km/s. Finally, combining stellar orbital information with an upper limit of 8
km/s for the intrinsic proper motion of Sgr A* (perpendicular to the Galactic
plane), we place a lower limit on the mass of Sgr A* of 4 x 10^5 Msun.
