Central Bureau for Astronomical Telegrams
IAUC 6390: GRS 1739-278; X-RAY SOURCES
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Circular No. 6390
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
T. Takeshima, J. K. Cannizzo, and R. Corbet, Goddard Space
Flight Center (GSFC) and Universities Space Research Association;
and F. E. Marshall, GSFC, report: "The Rossi X-ray Timing Explorer
(RXTE) observed GRS 1739-278 during Mar. 31.754-31.862 UT. The
pointing position was slightly offset (to R.A. = 17h42m05s, Decl. =
-27o37'.2, equinox 2000.0) in order to reduce possible contamination
from the nearby bright source GRO 1744-28. The source flux in the
PCA band (2-60 keV) was 490 mCrab, corrected for the offset from the
source, and the spectrum is very soft. There were no detectable
oscillations with periods between about 0.002 and about 256 s. In
addition, GRS 1739-278 was detected during several slews between
other targets, and the following fluxes were found: Mar. 16, 810
mCrab; 22, 430; Apr. 21, 300. Errors on the fluxes from the slew
data are conservatively estimated to be 10 percent. After standard
processing, data from the pointed observation of GRS 1739-278, as
well as other public domain XTE observations, are available over the
Internet. Information on how to obtain these data can be found at
http://heasarc.gsfc.nasa.gov/0/docs/xte/xte_1st.html/ (see 'TOO
News' for a spectrum and lightcurve)."
X-RAY SOURCES
A. M. Levine, H. Bradt, D. Chakrabarty, W. Cui, J. G. Jernigan,
E. Morgan, R. Remillard, R. Shirey, and D. A. Smith, Center for
Space Research and Department of Physics, Massachusetts Institute
of Technology, report that five galactic and Large Magellanic Cloud
x-ray sources, in preliminary results from the RXTE All Sky Monitor
(ASM) data, appear to have intensified in the band 2-10 keV since
late March. The blackhole candidate LMC X-3 has increased from
about 15 mCrab in late March to about 40 mCrab. The recurrent
transient 4U 1630-47 intensified from < 20 mCrab to about 200 mCrab
around Mar. 20 and remains steady at that level. The strength of
burster and QPO source 4U 1705-44 has grown linearly with time from
Mar. 20 to Apr. 28, at which time it had a flux of about 200 mCrab.
The rapid burster MXB 1730-335 suddenly appeared in outburst around
Apr. 18, when it appeared to peak at about 200 mCrab; it has
weakened since the peak to a level of about 100 mCrab. Finally,
the ASM also detects GRS 1739-278 (IAUC 6348) at a level of about
250 mCrab in early Mar., reaching a peak of about 800 mCrab around
Mar. 20, and declining to an intensity of about 350 mCrab in late
April.
(C) Copyright 1996 CBAT
1996 May 1 (6390) Daniel W. E. Green
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