RADIO MONITORING OF GRS-1915+105

We present the results from 5 months of radio monitoring of the high-e nergy source GRS 1915+105, which produces ejecta with apparent superlu minal motions. The observations reported here were carried out with th e Very Large Array and Nancay radiotelescopes at several frequencies f rom 1993 December to 1994 April. During this period two major outburst s with nux densities greater than or equal to 1 Jy were observed. From the observations reported here we derive (1) an upper limit for the i nterval of time during which the plasma clouds are accelerated to rela tivistic velocities, (2) the evolution of the spectral indices during outbursts, and (3) the polarization of the radio emission from the eje cted plasma clouds. We also present here the observations of atomic hy drogen absorption used to derive a kinematic distance of 12.5 +/- 1.5 kpc for GRS 1915+105. The comparison of the radio monitoring reported here with the hard X-ray light curve observed by BATSE during the same period of time will provide clues for a better understanding of the r elativistic ejections observed from Galactic high-energy sources.