GRAVITATIONAL LENSING AND PROPER MOTIONS OF STARS SURROUNDING THE GALACTIC-CENTER

We examine lensing by the black hole in the Galactic center. We use th e new photometric data in the infrared to estimate the density of star s in the star cluster surrounding the black hole. We calculate the pro bability of lensing by the black hole, the rate of the new events and the influence of lensing on the velocity distribution of proper motion s of stars. The relative importance of lensing has its maximum at dist ances similar to 10 mas from the star cluster center. The measurement of the proper motion of stars on the scale of similar to 3 mas would b e necessary to investigate the orbits of stars at distances similar to 10(3)r(g) from the black hole. In principle the deformation of the pr ojected orbit shape by lensing may serve as a way to estimate the angu lar momentum of the black hole.