Central Bureau for Astronomical Telegrams
IAUC 6822: 4U 1630-47; 1SAX J0054.9-7226
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Circular No. 6822
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
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4U 1630-47
E. Kuulkers, Oxford University; S. Dieters, University of
Alabama, Huntsville; M. McCollough, Universities Space Research
Association and Marshall Space Flight Center; M. Wieringa,
Australia Telescope National Facility, Narrabri; M. Buxton, Mount
Stromlo and Siding Spring Observatories, Australian National
University; and R. Remillard, Massachusetts Institute of Technology
(MIT), on behalf of the RXTE/ASM team at MIT and Goddard Space
Flight Center, NASA, report: "The RXTE ASM (2-12 keV) shows that
the recurrent blackhole x-ray transient 4U 1630-47 (cf. IAUC 6389)
has started to become active again, as predicted by Kuulkers et al.
(1997, MNRAS 291, 81). It rose to about 40 mCrab between Feb. 1.0
and 2.7 UT, where it stayed more or less constant for the next
about 6 days. It then rose to about 60 mCrab on Feb. 8.3 and about
90 mCrab on Feb. 9.3. Subsequent RXTE PCA observations on Feb. 9.7
show the source at 140 mCrab (2-60 keV). More RXTE observations
have been scheduled. GRO BATSE has also detected 4U 1630-47
between Feb. 1 and 6 with a maximum flux of 360 mCrab (20-100 keV)
with a photon index near -2.5. ATCA observations at 8640 MHz on
Feb. 9.1 and 9.8 failed to detect a radio counterpart and set an
upper limit of 0.7 mJy. This source has shown similar x-ray
properties to the Galactic superluminal sources GRO J1655-40 and
GRS 1915+105 and so may show relativistic ejections during its
outburst. No radio or optical counterpart has been identified yet
for this source, and we therefore urge observations at other
wavelengths. More information on 4U 1630-47 can be found at the
URL http://www-astro.physics.ox.ac.uk/~erik/1630/index.html."
1SAX J0054.9-7226
G. L. Israel, Osservatorio Astronomico di Roma, communicates
on behalf of the BeppoSAX Science Team: "The position of the
XTE/BeppoSAX 59-s transient x-ray pulsar in the Small Magellanic
Cloud, reported on IAUC 6818, is also included in an archival ROSAT
HRI observation obtained on 1996 Apr. 26. The source is detected
at R.A. = 0h54m56s.1, Decl. = -72o26'45" (equinox 2000; uncertainty
radius 10") with a 0.1-2.4-keV flux of about 1.6 x 10E-13 erg sE-1
cmE-2. Visual inspection of European Southern Observatory plates
reveals three unclassified stars (V > 15.5) within the refined
error circle. Optical follow-up observations of these candidates
are strongly encouraged."
(C) Copyright 1998 CBAT
1998 February 10 (6822) Daniel W. E. Green
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