Circinus X-1

L. J. Kaluzienski and S. S. Holt, Goddard Space Flight Center, report that the Ariel 5 all-sky monitor recorded a transition in the 16.6-day cycle of Cir X-1 on Sept. 5.126 +/- 0.046 UT, consistent with the ephemeris on IAUC 3099. A rapid turn-on in this cycle occurred on Aug. 28.00 +/- 0.08. The 3-6 keV flux during the half-day prior to turn-off was measured at 1.37 +/- 0.15 times the Crab (with a dip to 0.38 +/- 0.07 in the ~ 4 h immediately preceding turn-off). I. S. Glass, South African Astronomical Observatory, reports that there was a very rapid rise in the infrared brightness of the Mayo et al. candidate (IAUC 2957, 3095) on Sept. 5.73 UT. The complete lightcurve is sawtooth shaped.