X-Ray Transient in Centaurus

L. Kaluzienski and S. Holt, Goddard Space Flight Center, report the detection of an outburst from a source in Centaurus with the Ariel 5 all-sky monitor. Observations of this region in the instrument coarse spatial resolution mode yield an error box of 2o x 5o roughly centered on the position of Cen X-4, a transient x-ray source last observed in 1969 July. The source appeared between ~ 1979 May 11d05h and 13d01h UT, the flux at 3-6 keV increasing from a level of < 0.1 Crab to ~ 0.7 Crab during that time. The source continued to brighten steadily, and when last observed early on May 14 had attained an intensity of ~ 1.4 Crab. Although the positional uncertainty of the source is relatively large, its location at high galactic latitude and transient nature support the tentative identification with Cen X-4.