  W51 is a giant radio complex lying along the tangent to the Sagitarius arm at
a distance of about 7kpc from Sun, with an extension of about 1deg in the sky.
It is divided into three components A,B,C where W51A and W51B consist of many
compact HII regions while W51C is a supernova remnant. We have made continuum
radio observations of these HII regions of the W51 complex at 240,610,1060,1400
MHz using GMRT with lower resolution 20''x15'' at the lowest frequency. The
observed spectra of the prominent thermal subcomponents of W51 have been fitted
to a free-free emission spectrum and their physical properties like electron
temperatures and emission measures have been estimated. The electron
temperatures from continuum spectra are found to be lower than the temperatures
reported from radio recombination line (RRL) studies of these HII regions
indicating the need for a filling factor even at this resolution. Also, the
observed brightness at 240MHz is found to be higher than expected from the best
fits suggesting the need for a multicomponent model for the region.
