  We present results of monitoring observations of the micro-quasars CygnusX-1
and Cygnus X-3 at 0.61 and 1.28 GHz. The observations were performed with Giant
Meter-wave Radio Telescope, GMRT, between 2003 June and 2005 January. Variable,
unresolved sources were found in both cases. Cyg X-1 was detected in about half
of the observations, with a median flux density about 7 mJy at each frequency.
The results show clearly that there is a break in the spectrum above 1.28 GHz.
The variations in Cyg X-1 may be due to refractive interstellar scintillation.
Cyg X-3 was detected in each observation, and varied by a factor of 4. For this
source, models of the scintillation suggest a very long timescale (of the order
of 40 yr at 1.28 GHz), and therefore we believe that the variations are
intrinsic to the source.
