RADIO MONITORING OF GRS-1915+105

We present the results from 5 months of radio monitoring of the high-energy source GRS 1915+105, which produces ejecta with apparent superluminal motions. The observations reported here were carried out with the Very Large Array and Nancay radiotelescopes at several frequencies from 1993 December to 1994 April. During this period two major outbursts 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 interval of time during which the plasma clouds are accelerated to relativistic velocities, (2) the evolution of the spectral indices during outbursts, and (3) the polarization of the radio emission from the ejected plasma clouds. We also present here the observations of atomic hydrogen 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 relativistic ejections observed from Galactic high-energy sources.