Central Bureau for Astronomical Telegrams
IAUC 6383: GRS 1739-278
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Circular No. 6383
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Postal Address: Central Bureau for Astronomical Telegrams
Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions)
BMARSDEN@CFA.HARVARD.EDU or DGREEN@CFA.HARVARD.EDU (science)
Phone 617-495-7244/7440/7444 (for emergency use only)
GRS 1739-278
P. Durouchoux, Service d'Astrophysique, Saclay; I. A. Smith,
Rice University; K. Hurley, University of California, Berkeley; A.
S. B. Schultz, NASA Ames Research Center; L. B. F. M. Waters,
University of Amsterdam (UA); J. van Paradijs, University of
Alabama at Huntsville and UA; and P. Wallyn, Jet Propulsion
Laboratory, report: "We observed the GRS 1739-278 region (IAUC
6348) with the SEST 1.3-mm bolometer (center frequency 235 GHz;
band 50 GHz; beam 23") on Mar. 25.42 UT. The antenna was pointed
toward the source direction given by Borozdin {it et al. (IAUC
6350). The pointing procedure was as follows: 10 s in the source
direction, followed by 10 s off-source (70" offset in azimuth in
one direction) and 10 s off-source (70" offset in the opposite
azimuthal direction). We accumulated a total of 2400 s on-source,
and used Uranus for calibration. The atmospheric transmission was
very good (tau = 0.06, corresponding to an atmospheric conversion
factor of about 7 percent). We detected a possible source, with a
flux density of 17.6 +/- 5.3 mJy. Dividing the 2400 s on-source
observation into three sets of 800 s suggests that the source is
variable: Mar. 25.445-25.476, 31.0 +/- 8.9 mJy; Mar. 25.476-25.493,
17.0 +/- 8.8 mJy; Mar. 25.494-25.526, 1.25 +/- 10.2 mJy. This
variability suggests that we located the source, although we
caution that our beam did not cover the entire x-ray error box. We
encourage further multiwavelength observations to confirm and
monitor this potential counterpart."
R. M. Hjellming and M. P. Rupen, National Radio Astronomy
Observatory; and J. Marti, University of Barcelona; F. Mirabel,
Saclay; and L. F. Rodriguez, Universidad Nacional Autonoma de
Mexico, report the VLA detection of a probable radio counterpart to
GRS 1739-278, discovered by the SIGMA/Granat team (IAUC 6348):
"With a position of R.A. = 17h42m40s.03 +/- 0s.02, Decl. =
-27o44'52".7 +/- 0".3 (equinox 2000.0), the radio source is just
inside the 1' error radius of the MIR-KVANT-TTM team's (IAUC 6350)
position. Unlike four other radio sources in the 4.9-GHz field of
observation, which are outside of the 1' error region and which
appear stable in radio flux, this radio source was 1.1, 1.5, 3.7,
and 4.7 mJy at 4.9 GHz on Mar. 24, Apr. 8, 14, and 18, respectively,
indicating a timescale of variations typical of the synchrotron
radiation sources associated with x-ray transients and x-ray
binaries."
(C) Copyright 1996 CBAT
1996 April 18 (6383) Daniel W. E. Green
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