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IAUC 8070: 2003ao; X1901+031; IGR J16318-4848

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                                                  Circular No. 8070
Central Bureau for Astronomical Telegrams
Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions)
URL http://cfa-www.harvard.edu/iau/cbat.html  ISSN 0081-0304
Phone 617-495-7440/7244/7444 (for emergency use only)

SUPERNOVA 2003ao IN NGC 2993
     Further to IAUC 8069, J. Graham and W. Li report the LOTOSS
discovery of apparent supernova (mag about 17.3) on an unfiltered
KAIT image taken on Feb. 10.4 UT.  The new object is confirmed at
about the same brightness in an earlier image taken on Jan. 30.4.
SN 2003ao is located at R.A. = 9h45m48s.46, Decl. = -14o22'14".0
(equinox 2000.0), which is 2".3 east and 8".4 south of the nucleus
of NGC 2993.  A KAIT image taken on 2002 Dec. 2.4 showed nothing at
this position (limiting mag about 19.0).

     D. Galloway, R. Remillard, and E. Morgan, Massachusetts
Institute of Technology; and J. Swank, Goddard Space Flight Center,
on behalf of the RXTE Instrument Teams, report a new x-ray outburst
in a transient last seen in 1970-1971 (Forman et al. 1976, Ap.J.
206, L29):  "The ASM position is R.A. = 19h03m33s, Decl. = +3 12'.4
(equinox J2000.0; estimated 3' uncertainty at 90-percent
confidence).  This position is within the 10' error box originally
estimated for X1901+031.  The current outburst appears to have
begun on 2003 Jan. 31 with a flux of 40(8) mCrab at 2-10 keV,
rising to a steady flux of 130 mCrab on Feb. 9 and 10.  Brief
follow-up observations with the RXTE PCA instrument on Feb. 10 show
pulsations with a period of 2.763 s.  We encourage efforts to
locate the optical counterpart, noting a likely optical companion
with an early-type spectrum or Be classification."

IGR J16318-4848
     H. Murakami and T. Dotani, Institute of Space and
Astronautical Science; and R. Wijnands, University of St Andrews,
report on the ASCA archival data analysis of the field of IGR
J16318-4848 (IAUC 8063).  A clear x-ray source was detected with
both GIS and SIS at a position consistent with that of IGR
J16318-4848, from a net exposure of 4000 s on 1994 Sept. 3.2 UT.
The SIS position was determined as R.A. = 16h31m49s, Decl. =
-48o49'.2 (equinox 2000.0; uncertainty about 0'.8).  Murakami et
al. add:  "The source had a highly absorbed spectrum.  If we assume
a power-law continuum with a photon index fixed to 1.0, the
neutral-hydrogen-absorption column density is estimated to be 4 +/-
2 x 10**23 cm**-2.   The source flux was about 4 x 10**-11 erg
s**-1 cm**-2 in 2-10 keV when corrected for the absorption.
Although the data statistics were not very high, we noticed a hint
of an iron emission line at 6.4 keV."

                      (C) Copyright 2003 CBAT
2003 February 11               (8070)            Daniel W. E. Green

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