Electronic Telegram No. 3533
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 2013cs IN ESO 576-17 = PSN J13151481-1757556
     S. Howerton, Arkansas City, KS, U.S.A.; R. H. McNaught, Australian
National University; A. J. Drake, S. G. Djorgovski, M. J. Graham, A. Mahabal,
and R. Williams, California Institute of Technology; J. L. Prieto, Princeton
University; M. Catelan, Pontificia Universidad Catolica de Chile; and E.
Christensen and S. M. Larson, Lunar and Planetary Laboratory, University of
Arizona, report the Catalina Real-time Transient Survey discovery of an
apparent supernova in unfiltered Siding Spring Survey images:

 SN       2013 UT       R.A. (2000.0) Decl.      Mag.      Offset
 2013cs   May 14.59   13 15 14.81  -17 57 55.6   14.7    28".7 E, 4".8 N

The variable was designated PSN J13151481-1757556 when it was posted at the
Central Bureau's TOCP webpage and is here designated SN 2013cs based on the
spectroscopic confirmation reported below.  L. Elenin, Lyubertsy, Russia; and
I. Molotov, Moscow, report that unfiltered CCD images (limiting mag about
19.4) remotely taken with a 0.45-m f/2.8 telescope at the ISON-NM Observatory
near Mayhill, NM, USA, on May 16.171 UT show 2013cs at mag 14.5 and position
end figures 14s.82 +/- 0".07, 55".2 +/- 0".09; their image is posted at
website URL http://spaceobs.org/images/TOCP/PSNJ13151481-1757556-20130516.png.

     M. Yamanaka, Kyoto University; and K. Takaki, Y. Moritani, and K. S.
Kawabata, Hiroshima University, obtained a low-resolution optical spectrum
(range 480-900 nm) of PSN J13151481-1757556 = SN 2013cs on May 15.5 UT with
the 1.5-m Kanata telescope (+ HOWPol) at the Higashi-Hiroshima Observatory.  A
comparison with a library of supernova spectra using GELATO (Harutyunyan et
al. 2008, A.Ap. 488, 383) suggests that the spectrum is consistent with that
of the type-Ia supernova 2002bo at 10 days before B-band maximum.  After
correcting for the recession velocity of the host galaxy, the spectrum
exhibits absorption lines at 485, 520, 537, 570, 603, and 789 nm, which are
identified as an Fe II multiplet, S II 545.4- and 564.0-nm, Si II 597.2- and
635.5-nm, and the Ca II infrared triplet, respectively.  The line velocities
of Si II 635.5-nm and the Ca II infrared feature reach 15000 and 18000 km/s,
respectively.  The C II 658.0-nm absorption line is also clearly seen at 627
nm.


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      superseded by text appearing later in the printed IAU Circulars.

                         (C) Copyright 2013 CBAT
2013 May 18                      (CBET 3533)              Daniel W. E. Green