A New Transient Source Observed by UHURU

A strong X-ray source appeared sometime between 1971 March 25 and 1971 Augnst 17. On Augnst 23, its intensity, as observed by the Uhuru satellite, was about twice that of the Crab Nebula, corresponding to about 3.0 X 108 ergs cm s- in the range 2-6 keV. On 1971 December 20, its intensity had declined to one-tenth of that value in the same energy range. Its spectrum was quite steep, and fit a power law with an average energy spectral index of 3.0. The variation of X-ray intensity over a 5-month period shows qualitative differences from the previously observed transient X-ray sources, Cen XR-2 and Cen XR .