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IAUC 7032: 1998ef; XTE J1906+09

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                                                 Circular No. 7032
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
Phone 617-495-7244/7440/7444 (for emergency use only)

     W. D. Li, M. Modjaz, E. Halderson, T. Shefler, J. Y. King, M.
Papenkova, R. R. Treffers, and A. V. Filippenko, University of
California at Berkeley, report their discovery of an apparent
supernova during the course of the Lick Observatory Supernova
Search with the 0.8-m Katzman Automatic Imaging Telescope (KAIT).
SN 1998ef was discovered on an unfiltered image taken on Oct. 18.3
UT (mag about 15.2), and confirmed on an earlier image taken on Oct.
14.3 (mag about 16.7).  SN 1998ef is located at R.A. = 1h03m26s.87,
Decl. = +32o14'12".4 (equinox 2000.0), which is about 6".1 east and
2".1 south of the nucleus of UGC 646.  A KAIT image of the same
field on Oct. 10.3 showed nothing at the position of the new star
(limiting mag about 18.0).  Filippenko further reports that
inspection of a CCD spectrum of SN 1998ef obtained on Oct. 19 by C.
De Breuck (Lawrence Livermore National Laboratory) with the 3-m
Shane reflector at Lick reveals that the object is a type-Ia
supernova, with well-developed Si II lines.

XTE J1906+09
     T. Takeshima, Goddard Space Flight Center and Universities
Space Research Association; and T. Murakami, Institute of Space and
Astronautical Science, on behalf of the RXTE Science Operations
Center and ASCA team, report:  "Simultaneous observations of SGR
1900+14 with ASCA (Sept. 16.794-17.831 UT) and RXTE/PCA (Sept.
16.826-16.988 and 17.281-17.388) confirmed that the 89-s pulsar XTE
J1906+09 (Marsden et al. 1998, Ap.J. 502, L129) is a separate
source from SGR 1900+14 (IAUC 7008).  While RXTE/PCA detected
significant 89-s pulsations, ASCA saw only 5.17-s pulsations from
SGR 1900+14.  Scans with the RXTE/PCA on Sept. 21.45 localized the
89-s pulsar to R.A. = 19h05m20s, Decl. = +9 02'.5 (equinox 2000.0),
which was about 2' outside the ASCA/GIS field-of-view.  The error
radius of 2'.0 (90-percent confidence level) is dominated by
systematic uncertainties due to intensity variations of the 89-s
pulsar and of nearby sources during the scans.  The average flux of
XTE J1906+09 and its pulse fraction during the scan observation
were 4.1 mCrab (2-10 keV) and 66 percent, respectively.  The
pulsating x-ray flux declined below 0.3 mCrab (2-10 keV) by Oct. 2,
but observations at other wavelengths to identify the counterpart
are encouraged."

                      (C) Copyright 1998 CBAT
1998 October 19                (7032)            Daniel W. E. Green

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