X-ray observations of SS 433, 1974 1980

Observations of the X-ray flux and spectral variability of SS433 made with instruments on board the Ariel V and VI satellites during the period 1974 to 1980 are presented. The Sky Survey Instrument on Ariel V has found variations in source strength in the 2-15 keV region in the range 4-11 milli-Crab, or 1.6-4.5 counts/sec during the period October 1974-January 1980. Data folding at periods from 9 to 200 days reveals peaks in the deviation from the mean flux value of 7.8 milli-Crab at 82 and 164 days, although no evidence for periodicity at 13 days is found. Observations of the 1-50 keV spectrum of SS433 from Ariel VI in August 1979 and July and August 1980 show that when the source spectrum is harder, it is more heavily cut off, and suggest a significant brightening over the last year. The observation of 164-day variability in X-ray flux is noted to support the suggestion that the ambient gas density varies with direction from the beam source.