4U 1630-47

S. Holt, L. Kaluzienski, R. Mushotzky, F. Boldt and P. Serlemitsos, Goddard Space Flight Center, report that recent observations of the galactic plane in Norma with the Ariel 5 all-sky monitor reveal the presence of a bright source at a position consistent with that of the recurrent transient x-ray source 4U 1630-47. The 3-6-keV flux measured on Oct. 8 (shortly after the source entered the field of view of the detector) was approximately one-third that of the Crab Nebula (assuming an intensity for the nearby bright variable source 4U 1642-45 equal to the observed Uhuru maximum). Quick-look data obtained with the HEAO-A2 experiment on Sept. 6 also show a source at approximately this intensity roughly consistent with the position of 4U 1630-47. The latest outburst from this source was observed in 1977 Nov. (IAUC 3144), with subsequent detections reported in 1978 Mar. (IAUC 3197) and June (IAUC 3227). This, if the identification of the above source with 4U 1630-47 is correct, the present observations are indicative of a prolonged emission plateau or extended secondary maximum in the decay of this object. In either case, this would represent the longest-lived flaring episode of a 'transient' source yet observed.