[IAUC] CBET 3304: 20121124 : SUPERNOVA 2012gn IN UGC 4981 = PSN J09240176+6833433

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                                                  Electronic Telegram No. 3304
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
CBAT Director:  Daniel W. E. Green; Hoffman Lab 209; Harvard University;
 20 Oxford St.; Cambridge, MA  02138; U.S.A.
e-mail:  cbatiau en eps.harvard.edu (alternate cbat en iau.org)
URL http://www.cbat.eps.harvard.edu/index.html
Prepared using the Tamkin Foundation Computer Network


SUPERNOVA 2012gn IN UGC 4981 = PSN J09240176+6833433
     J. Newton and T. Puckett report the discovery of an apparent supernova
(mag 16.7) on unfiltered CCD images (limiting mag 19.0-19.2) taken with a
0.35-m reflector at Portal, AZ, U.S.A., on Nov. 11.507 and 12.494 UT in the
course of the Puckett Observatory Supernova Search.  The new object is located
at R.A. = 9h24m01s.76, Decl. = +68o33'43".3 (equinox 2000.0), which is 1".5
west and 1".9 south of the center of UGC 4981.  Puckett has posted an image of
the variable at website URL http://www.possdata.com/PSN09240176+6833433.jpg.
The variable was designated PSN J09240176+6833433 when it was posted at the
Central Bureau's TOCP webpage and is here designated SN 2012gn based on the
spectroscopic confirmation reported below.  Additional CCD magnitudes for
2012gn:  2011 Oct. 9, [19.2 (Puckett); 2012 Nov. 14.45, 16.4 (J. Brimacombe,
Cairns, Australia; luminance filter; position end figures 01s.88, 43".8;
image posted at URL http://www.flickr.com/photos/43846774@N02/8186716379/).

     T.-M. Zhang, National Astronomical Observatory of China (NAOC); and X.-F.
Wang, Tsinghua Center for Astrophysics, Tsinghua University, Beijing, report
that an optical spectrogram (range 400-8800 nm) of PSN J09240176+6833433 = SN
2012gn, obtained on Nov. 16.8 UT with the 2.16-m telescope (+ OMR) at Xinglong
Station of the NAOC, shows the variable to be a type-II supernova.  The
spectrum is blue and relatively featureless, with a broad, low-contrast
hydrogen balmer emission lines.  Cross-correlation with a library of supernova
spectra using the "Supernova Identification" code (SNID; Blondin and Tonry
2007, Ap.J. 666, 1024) shows that 2012gn matches with SN 2004et at +2 days.
Adopting a recession velocity 3968 km/s (after Falco et al. 1999, PASP 111,
438) for the host galaxy (UGC 4981), the photospheric expansion velocities,
inferred from the absorption minima of H_alpha and H_beta, are about 9000
km/s.


NOTE: These 'Central Bureau Electronic Telegrams' are sometimes
      superseded by text appearing later in the printed IAU Circulars.

                         (C) Copyright 2012 CBAT
2012 November 24                 (CBET 3304)              Daniel W. E. Green