Observations of six binary x-ray sources with the UCSD OSO-7 x-ray telescope

We report observations of six binary X-ray sources with the UCSD OSO-7 X-ray telescope: SMC X-1, Vel XR-1 (2U 0900-40), Cen X-3, Her X-1, Cyg X-1, and Cyg X-3. The results include: (1) a simultaneous X-ray and optical observation of SMC X-1; (2) a refined eclipse period for Vel XR-1, P=8/sup d/.962plus-or-minus0/sup d/.004; (3) a factor of 2 decrease in the 7--11 keV flux during the non-eclipsed portion (phase 0.2--0.8) of the 2/sup d/.08712 cycle of Cen X-3 while the 11-18 keV flux remained essentially constant; (4) a 7-26 keV ''turn-on'' of Her X-1 with respect to the 35-day cycle which occurred by 1972 December 22.84plus-or-minus0.06 and was approx.0.5 days earlier than the 2--6 keV ''turn-on'' reported from Uhuru satellite observations; (5) a flattening in the shape of the Cyg X-3 spectrum between 1972 July (dN/dEproportional1/E2.07/sup plus-or-minus//sup 0//sup .1//sup 3/ photons cm -2 s-1 keV-1) and 1973 February (dN/dEproportional1/exp(9.6plus-or-minus3.5 keV/E)8/31/E2.7/sup plus-or-minus//sup 0//sup .4/); (6) a summary of spectra for all the X-ray sources