Electronic Telegram No. 3011
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 2012X
     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 17.9) in
unfiltered images taken on Jan. 29.26 UT with the 0.45-m ROTSE-IIIb telescope
at McDonald Observatory.  The transient was observed again at similar brightness
during the following three days (with large photometry uncertainties).  There
was no detection at the same position before Jan. 25, down to a limiting
magnitude of about 18.5.  The new object is located at R.A. = 11h29m20s.8,
Decl. = +53o00'41".2 (equinox 2000.0; uncertainty about 1"), which is 5".5 east
and 5".4 south of the proposed host galaxy (SDSS J112920.21+530046.6, whose
SDSS redshift is z = 0.102); a finding chart is posted at website URL
http://www.rotse.net/rsvp/j112920.8+530041/ROTSE3_J112920.8+530041.jpg.
     A spectrum, obtained on Feb. 2.29 UT with the 9.2-m Hobby-Eberly
Telescope (+ Marcario Low-Resolution Spectrograph) by J. Caldwell, shows that
2012X is a type-Ia supernova about one week before maximum brightness.  The
spectrum contains the Si II 635.5-nm line and several other characteristic
type-Ia-supernova features.  According to SNID (Blondin and Tonry 2007, Ap.J.
666, 1024), the spectrum resembles that of SN 1998aq at a few days before
maximum.  The median redshift estimate is 0.101, in good agreement with the
proposed host.  Adopting this redshift, the the rest-frame photospheric
velocity, estimated from the minimum of the Si II 635.5-nm feature, is about
11200 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      superseded by text appearing later in the printed IAU Circulars.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 February 3                  (CBET 3011)              Daniel W. E. Green