The X-ray spectrum of 3C 273

We report an X-ray spectral measurement of the quasar 3C 273 with the HEAO A2/sup 32/ experiment in 1978 June/July. The best power-law fit to the photon flux over the range 2--60 keV gives a slope of 1.41 +- 0.02. However, structure is observed, indicating a slope of 1.52 between 2 and 9 keV and a slight flattening between 9 and 30 keV. Observations with the same experiment in 1977 December and OSO 8 in 1976 June allow us to confirm reports of 40% intensity variability on the time scale of months, although within limits provided by the poorer statistical quality of the additional data we do not discern any spectral change. Absorption from the source is found to be be low, with the 1978 data yielding a 90% confidence upper limit to the hydrogen column density of 4.5 x 10/sup 21/ atoms cm/sup -2/.