Electronic Telegram No. 3157
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 2012dc = PSN J15381795+2544173
     An apparent supernova (mag 18.6) was discovered by V. Shumkov on
unfiltered 180-s MASTER CCD images taken with the Kislovodsk robotic 0.40-m
f/2.5 reflector on June 20.78, 20.80, and 20.82 UT; the new object is located
at R.A. = 15h38m17s.95, Decl. = +25d44'17".3 (equinox 2000.0).  The discovery
images are at URL http://master.sai.msu.ru/static/OT/153817.95254417.3_1.png.
The variable was designated PSN J15381795+2544173 when it was posted at the
Central Bureau's TOCP webpage and is here designated SN 2012dc based on the
spectroscopic confirmation reported below.  Additional CCD magnitudes for
2012dc:  June 21.813, 18.6 (D. Denisenko and V. Lipunov, MASTER-Kislovodsk
robotic telescope); 23.427, 19.0 (Joseph Brimacombe, Cairns, Australia;
41-cm RCOS + STL6K camera + infrared filter; bandpass > 700 nm; position end
figures 17s.92, 17".1).  Brimacombe's image is posted at the following
website URL:  http://www.flickr.com/photos/43846774@N02/7429301428/.
The June 21 MASTER image is posted at http://tinyurl.com/7lv27k6.

     J. M. Silverman, D. P. Cohen, and A. V. Filippenko, University of
California, Berkeley, report that inspection of a noisy CCD spectrum (range
340-1000 nm), obtained on June 27.3 UT with the Shane 3-m reflector (+ Kast
spectrograph) at Lick Observatory, shows that PSN J15381795+2544173 = SN
2012dc is a type-Ia supernova.  After removal of the host-galaxy recession
velocity of 26952 km/s (Sloan Digital Sky Survey Data Release 6), the
absorption minimum of the Si II 635.5-nm line is found to be blueshifted by
about 11700 km/s.  Cross-correlation with a library of supernovae spectra
using the "SuperNova IDentification" code (SNID; Blondin and Tonry 2007, Ap.J.
666, 1024) indicates that 2012dc is a normal type-Ia supernova roughly four
days past maximum brightness.


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      superseded by text appearing later in the printed IAU Circulars.

                         (C) Copyright 2012 CBAT
2012 July 1                      (CBET 3157)              Daniel W. E. Green