Electronic Telegram No. 2992
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@eps.harvard.edu (alternate cbat@iau.org)
URL http://www.cbat.eps.harvard.edu/index.html
Prepared using the Tamkin Foundation Computer Network


SUPERNOVA 2012O IN NGC 4906
     W. Zheng, University of Michigan; J. Vinko, University of Szeged;
G. H. Marion, Harvard-Smithsonian Center for Astrophysics; R. Quimby, IPMU,
University of Tokyo; N. Whallon, A. Romadan, N. Wagner, and C. Akerlof,
University of Michigan; F. Yuan, Australian National University; and J. C.
Wheeler and E. Chatzopoulos, University of Texas, on behalf of the ROTSE
collaboration, report the discovery of a new supernova (mag about 15.5) in
unfiltered images taken on Jan. 18.33 UT with the 0.45-m ROTSE-IIIb telescope
at McDonald Observatory.  The transient was observed again at mag about 15.6
on Jan. 20.33, with no detection before Jan. 6 down to a limiting magnitude
of about 18.0.  The new object is located at R.A. = 13h00m39s.99, Decl. =
+27o55'24".4 (equinox 2000.0; uncertainty about 1"), which is 3".1 east and
1".8 south of the proposed host galaxy (NGC 4906, whose redshift is z =
0.0251; Rines et al. 2003, A.J. 126, 2152, via the SIMBAD website); a
finding chart is posted at the following website URL:
http://www.rotse.net/rsvp/j130040.0+275524/ROTSE3_J130040.0+275524.jpg
     A spectrum, obtained on 2012 Jan. 21.37 UT with the 9.2-m Hobby-Eberly
Telescope (+ Marcario Low-Resolution Spectrograph) by Matthew Shetrone, shows
that 2012O is a typa-Ia supernova about a week past maximum.  Beside the
characteristic Si II, S II, and Fe II features, the spectrum also contains
many weak, narrow absorption features, probably due to the contamination by
the host galaxy.  The SNID code (Blondin and Tonry 2007, Ap.J. 666, 1024)
finds good matches with several normal type-Ia-supernova templates, including
SN 2004L at six days and SN 2001fh at eight days after maximum.  The redshift
estimated by SNID agrees with the value given in SIMBAD (see above) for NGC
4906.  The expansion velocity at the photosphere, inferred from the absorption
minimum of the Si II 635.5-nm feature, is 9850 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      superseded by text appearing later in the printed IAU Circulars.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 January 25                  (CBET 2992)              Daniel W. E. Green