Radio emission from SS433

About ten years before the unusual properties of SS433 where known the object was already observed at radio wavelengths. It is almost certain that 4C04.66 is SS433. The positional coincidence between the optical object and the radio source is at least 0.2'' (Margon, 1984). The central source has been observed from 160 MHz to 22 GHz. At high frequencies the typical spectral index is about , a normal value for non-thermal sources. The spectrum flattens at low frequencies and probably turns over below 300 MHz. A significant fraction of the radio emission of SS433 is extended over spatial scales of a few arcseconds. The morphology of this extention is time variable. A large fraction of the extended radio emission is polarized (up to 20 percent). Together with the nonthermal spectral index it is likely that the origin of the radio emission is highly relativistic synchrotron radiation.