[IAUC] CBET 3237: 20120923 : SUPERNOVA 2012fb

[quai en eps.harvard.edu]

                                                  Electronic Telegram No. 3237
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 2012fb
     W. Zheng, University of Michigan; J. Vinko, University of Szeged; G. H.
Marion, Harvard-Smithsonian Center for Astrophysics; F. Ferrante, G. Dhungana,
and R. Kehoe, Southern Methodist University; R. Quimby, IPMU, University of
Tokyo; A. Romadan 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 17.0) in unfiltered images taken on Sept. 17.99 UT with
the 0.45-m ROTSE-IIId telescope at the Turkish National Observatory at
Bakirlitepe.  The transient was observed again at mag about 16.7 on Sept.
21.32 by the ROTSE-IIIb telescope at McDonald Observatory.  There was no
detection at the same position before Sept. 11, down to a limiting magnitude
of about 18.2.  The new object is located at R.A. = 1h50m51s.2, Decl. =
+33o08'25".4 (equinox 2000.0; uncertainty about 1"), which is 0".1 west and
2".7 north of the proposed host galaxy (SDSS J015051.24+330823.0, whose
photo-z redshift is z = 0.0405 +/- 0.0134); a finding chart is posted at URL
http://www.rotse.net/rsvp/j015051.2+330825/ROTSE3_J015051.2+330825.jpg.
     A spectrogram, obtained on Sept. 22.46 UT with the 9.2-m Hobby-Eberly
Telescope (+ Marcario Low-Resolution Spectrograph) by J. Caldwell, shows a
strong Si II 635.5-nm feature and other features due to S II and Fe II,
characteristics of a type-Ia supernova.  Comparison with other supernova-
template spectra with the SNID code (Blondin and Tonry 2007, Ap.J. 666,
1024) shows that the spectrum of 2012fb is most similar to those of the
normal type-Ia supernova 1994D at a few days before maximum.  The redshift
derived from the narrow H-alpha feature from the host galaxy is 0.038, in
very good agreement with the photo-z value given above.  The velocity at the
photosphere estimated from the minimum of the Si II 635.5-nm feature is
about 12000 km/s.


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                         (C) Copyright 2012 CBAT
2012 September 23                (CBET 3237)              Daniel W. E. Green