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Circular No. 5901
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Postal Address: Central Bureau for Astronomical Telegrams
Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
Telephone 617-495-7244/7440/7444 (for emergency use only)
TWX 710-320-6842 ASTROGRAM CAM EASYLINK 62794505
MARSDEN@CFA or GREEN@CFA (.SPAN, .BITNET or .HARVARD.EDU)


GRO J0422+32
P. Zhao, P. Callanan, M. Garcia, and J. McClintock, Smithson-
ian Astrophysical Observatory, write: "GRO J0422+32, a possible
black hole, is currently undergoing another unexpected and dramatic
outburst. Its optical counterpart has brightened by 4 mag during
the past two weeks at an average rate of 0.3 mag/day. CCD photome-
try obtained with the F. L. Whipple Observatory's 1.2-m telescope
gives the following R magnitudes: Nov. 21.52 UT, 19.27 +/- 0.03;
24.21, 19.43 +/- 0.09; 25.72, 19.16 +/- 0.05; 26.19, 18.78 +/-
0.07; Dec. 7.42, 15.45 +/- 0.02; 8.20, 15.50 +/- 0.02; 8.41, 15.38
+/- 0.02. The data from the last two nights indicate that the ob-
ject is now probably near its maximum for this outburst event. GRO
J0422+32 was discovered in outburst on 1992 Aug. 5 (IAUC 5580); two
subsequent, short-lived outbursts occurred on 1992 Dec. 20 (IAUC
5685) and 1993 Aug. 12 (IAUC 5842). It is unprecedented for an x-
ray nova to have four outbursts within 16 months. Since the cur-
rent outburst may also be short-lived, prompt observations at x-ray
and gamma-ray energies are strongly encouraged."


1993 December 8 (5901) Daniel W. E. Green