[IAUC] CBET 3190: 20120724 : SUPERNOVA 2012du IN NGC 7125 = PSN J21491632-6042426

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                                                  Electronic Telegram No. 3190
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 2012du IN NGC 7125 = PSN J21491632-6042426
     Greg Bock, Windaroo, Queensland, Australia, reports the discovery of an
apparent supernova (mag 15.3) by Stuart Parker (Oxford, Canterbury, New
Zealand) on unfiltered images taken on June 30.55 and July 1.48 UT using a
35-cm Celestron C14 reflector (+ ST10 CCD camera).  The new object is located
at R.A. = 21h49m16s.32, Decl. = -60d42'42".6 (equinox 2000.0; measured by
Bock using the USNO-B and UCAC3 catalogues), which is 2" east and 4" north of
the nucleus of the galaxy NGC 7125.  Nothing is visible at this position on
Digitized Sky Survey red and infrared images (limiting red magnitude > 19.
The variable was designated PSN J21491632-6042426 when it was posted at the
Central Bureau's TOCP webpage and is here designated SN 2012du based on the
spectroscopic confirmation reported below.  Additional CCD magnitudes for
2012du:  2012 May 19, [18.0 (Parker); July 1.701, 15.8 (Joseph Brimacombe,
Cairns, Australia; 43-cm CDK telescope + STL6K camera + infrared filter;
bandpass > 700 nm; position end figures 16s.22, 43".2; image posted at
website URL http://www.flickr.com/photos/43846774@N02/7484414708/); 3.636,
15.6 (Brimacombe; position end figures 16s.25, 43".6; image posted at URL
http://www.flickr.com/photos/43846774@N02/7498206362/); 17.781, 15.6
(Brimacombe; position end figures 16s.25, 43".8; image posted at URL
http://www.flickr.com/photos/43846774@N02/7595534698/).

     N. Morrell, Las Campanas Observatory, Carnegie Supernova Project; J.-R.
Gauthier, Cahill Center for Astronomy and Astrophysics, California Institute
of Technology; and M. Rauch, Carnegie Observatories, report that on July 22.4
UT they obtained an optical spectrogram (range 360-940 nm) of PSN
J21491632-6042426 = 2012du with the 6.5-m Magellan II (Clay) telescope (+
LDSS3) at Las Campanas Observatory.  Analysis of the data reveals that 2012du
is a type-II supernova.  Adopting for NGC 7125 the NED recession velocity of
3148 km/s (Schweizer 1987, Ap.J. Suppl. 64, 411), in coincidence with H-alpha
nebular emission from a surrounding H II region that appears to be present in
the supernova spectrum, the minimum of the H-beta absorption appears to be
blueshifted by 6000 km/s.  Unresolved Na I absorption at the redshift of the
host galaxy is present with an equivalent width of 0.057 nm.  Comparison with
a library of supernova spectra via the Supernova Identification tool (SNID,
Blondin and Tonry 2007, Ap.J. 666, 1024) provides excellent matches with a
number of type II-p supernovae at 2-3 weeks after explosion.


NOTE: These 'Central Bureau Electronic Telegrams' are sometimes
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                         (C) Copyright 2012 CBAT
2012 July 24                     (CBET 3190)              Daniel W. E. Green