Central Bureau for Astronomical Telegrams
IAUC 8171: 2003gs; NO 1998ev, 1999cu,, 1999dc
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Circular No. 8171
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
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SUPERNOVA 2003gs IN NGC 936
R. Evans, Hazelbrook, N.S.W., reports his visual discovery of
a supernova (mag 14.0) on July 29.75 UT with a 0.31-m reflector,
noting it to be located about 20" southeast of the nucleus of NGC
936 (R.A. = 2h27m.6, Decl. = -1 09', equinox 2000.0); nothing was
detected to mag 15 by Evans in a search of this galaxy on July 3.75.
Evans again found SN 2003gs at m_v = 13.8 on July 30.75. H.
Yamaoka, Kyushu University, reports red mag about 13.2 and the
following precise position for SN 2003gs from an unfiltered CCD
image taken on July 30.767 by T. Dobosz, Sydney, N.S.W.: R.A. =
2h27m38s.36, Decl. = -1 09'35".4 (equinox 2000.0; fourteen GSC 2.2
reference stars; fitting error about 0".3 in each coordinate),
which is 13".4 east and 14".6 south of the center of NGC 936. N.
Suntzeff, Cerro Tololo Interamerican Observatory (CTIO), reports
that a spectrogram (range 350-900 nm; resolution 2 nm) of SN 2003gs
was obtained by P. Candia and M. Stritzinger on July 30.4 with the
facility spectrograph on the CTIO 1.5-m telescope. The spectrum is
peculiar and is roughly consistent with a type-Ia supernova perhaps
1 week after maximum light; the Si II lines are redshifted by about
11000 km/s and are weak for this phase of the supernova. K.
Krisciunas, CTIO, reports the following preliminary magnitudes for
SN 2003gs from data obtained by J. Espinoza and D. Depoy with the
CTIO 1.3-m telescope on July 30.40: U about 14.70, B about 14.05,
V about 13.40.
NO SUPERNOVAE 1998ev, 1999cu, AND 1999dc
A. Gal-Yam and D. Maoz, Tel Aviv University, write that
reanalysis (using improved image-subtraction software) of numerous
unfiltered CCD images of the field of the galaxy cluster Abell 136,
obtained with the Wise Observatory 1-m telescope, shows that the
the source reported as SN 1998ev (cf. IAUC 7055) is probably not
variable. Similar reanalysis of images of the field of the galaxy
cluster Abell 1697 shows that the source reported as SN 1999cu (cf.
IAUC 7210) is indeed variable, although certainly not a supernova,
with a temporal behavior consistent with that of an active galactic
nucleus (AGN). R. Chornock and A. V. Filippenko, University of
California, Berkeley, report that inspection of a CCD spectrum
(range 320-930 nm), obtained on 2003 June 29 UT with the Keck-I
telescope, shows that the host galaxy of the object 1999dc (cf.
IAUC 7227) is, in fact, an AGN at a redshift of 0.791; Gal-Yam and
Maoz therefore conclude that 1999dc was probably not a supernova,
either.
(C) Copyright 2003 CBAT
2003 July 31 (8171) Daniel W. E. Green
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