ON THE PUZZLING NATURE OF THE X-RAY BINARY CIRCINUS-X-1

During 1989 March 30 to April 2, Circinus X-1 was monitored at 5 GHz by one or other of a pair of two-element Australia Telescope interferometers and the Hartebeesthoek antenna, South Africa, and by the Ginga satellite in the 1-37 keV energy range. Our observations show that Cir X-1 now has a very low level of radio emission, unlike the late 1970s and early 1980s during which intense flare activity often occurred near zero orbital phase. Also, the X-ray behaviour is strange in that it does not show the usual spectral states seen in low-mass X-ray binaries, yet exceeds the Eddington limit during flaring episodes.