X-ray studies of SS433

Results of Einstein Observations of SS433 are discussed which address both the nature of the diffuse X-ray lobes and the relationships between SS433 and W50, as well as the time variability and nature of the central X-ray source. The diffuse X-ray lobes extend out to the quasi-spherical shell seen in the radio maps of W50 and suggest that the X-ray lobes are powered by the interaction of shock-heating from the SS433 jets and the denser material in the W50 shell. The central X-ray source in SS433 is time variable but only on timescales of less than 500-1000 sec. Flares, in which the non-thermal spectrum hardens, are detected at two preferred phases in the 13.08 day binary orbit. Constraints on the central X-ray source size as well as a possible eclipse by the companion star suggest the compact object in SS433 may be a black hole (approx 10 solar mass).