Central Bureau for Astronomical Telegrams
IAUC 5395: GX 339-4; GALACTIC CENTER
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Read IAUC 5396
Circular No. 5395
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 or GREEN@CFA.BITNET MARSDEN or GREEN@CFAPS2.SPAN
GX 339-4
G. J. Fishman, B. A. Harmon, B. Rubin, M. H. Finger, R. B.
Wilson, W. S. Paciesas, and C. A. Meegan, Marshall Space Flight Center,
NASA, report for the BATSE Experiment Team: "Hard x-ray/gamma-
ray fluxes from the black hole candidate GX 339-4 have been
monitored daily by earth occultation for several months, except for
about 6-day periods when the source is not occulted. The source was
reported previously to exhibit a significant brightening (IAUC 5327,
5352) between 20 and 230 keV. This brightening period lasted about
2 months (June 25-Aug. 22), with the source remaining at 380 mCrab
(20-230 keV) until Sept. 22. The spectrum appears to extend to
energies of at least 430 keV. Between Sept. 22 and Oct. 1, flux
from GX 339-4 dropped below the current BATSE one-day sensitivity
level (about 0.1 Crab), with no significant flux detected as of Nov.
15."
GALACTIC CENTER
I. F. Mirabel, Service d'Astrophysique, Saclay; L. F. Rodriguez,
Universidad Nacional Autonoma de Mexico; and B. Cordier, J. Paul,
and F. Lebrun, Saclay, communicate: "We report preliminary results
from Very Large Array observations at 3.6, 6, and 20 cm, coordinated
with SIGMA and the Gamma Ray Observatory, during the following dates:
1991 Sept. 3, 7, Oct. 3, 7. We have also analysed the VLA archive
data obtained in 1989 March by Kulkarni and Prince (IAUC 5252).
Within the Einstein and SIGMA error circles of 1E 1740.7-2942, two
sources were present in 1989: source 'A' (R.A. = 17h40m42s.99, Decl.
= -29 43'25", equinox 1950.0) and source 'B' (R.A. = 17h40m42s.45,
Decl. = -29 43'05"). Source 'B' is double, has a non-thermal spectrum,
and is likely to be a background radio galaxy. Source 'A' is
time variable; it was detected in 1991 October with a flux of 0.15
mJy at 6 cm, which is about 3 times lower than the flux observed in
1989. Our data suggest that the source was below 0.1 mJy in 1991
August and September. These variations in the radio flux are
consistent with those observed from 1E 1740.7-2942 by SIGMA during the
last year (IAUC 5204). Because of this variability we confirm that
the source 'A' is the radio counterpart of 1E 1740.7-2942."
1991 December 2 (5395) Daniel W. E. Green
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