Electronic Telegram No. 3497
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 2013bt IN PGC 51271 = PSN J14211513+6134159
     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; S. M. Larson and E.
Christensen, Lunar and Planetary Laboratory, University of Arizona; and R. H.
McNaught, Australian National University, report the Catalina Real-time
Transient Survey discovery of an apparent supernova in unfiltered CCD images:

 SN       2013 UT         R.A. (2000.0) Decl.      Mag.      Offset
 2013bt   Apr. 18.39   14 21 15.13  +61 34 15.9    18.0    28".7 W, 29".4 S

The variable was designated PSN J14211513+6134159 when it was posted at the
Central Bureau's TOCP webpage and is here designated SN 2013bt based on the
spectroscopic confirmation reported below.  Additional CCD magnitudes for
2013bt:  Apr. 19.185 UT, 16.8 (Joseph Brimacombe, Cairns, Australia; remotely
with a 51-cm RCOS telescope + red filter at the New Mexico Skies observatory
near Mayhill, NM, USA; position end figures 15s.08, 15".0; images taken with a
luminance filter yield mag 17.6 and position end figures 15s.07, 14".9; image
posted at website URL http://www.flickr.com/photos/43846774@N02/8668092576/);
21.278, 17.4 (L. Elenin, Lyubertsy, Russia; and I. Molotov, Moscow; remotely
taken with a 0.45-m f/2.8 telescope at the ISON-NM Observatory near Mayhill;
position end figures 15s.16 +/- 0".1, 15".4 +/- 0".08; UCAC-4 reference stars;
limiting mag about 20.3; image posted at the following website URL:
http://spaceobs.org/images/TOCP/PSNJ14211513+6134159-20130421.png).

     L. Tomasella, A. Pastorello, S. Benetti, E. Cappellaro, M. Turatto, and
P. Ochner, Osservatorio Astronomico di Padova, Istituto Nazionale di
Astrofisica, report that optical spectroscopy (range 340-820 nm; resolution
1.3 nm), obtained on Apr. 19.08 UT with the Asiago 1.82-m Copernico Telescope
(+ AFOSC), shows that PSN J14211513+6134159 = SN 2013bt is a type-Ia supernova.
Adopting for the host galaxy, PGC 51271, the redshift z = 0.036446 (SDSS Data
Release 2, 2004; via NED), the best fit is obtained with several type-Ia
supernovae at about one week before maximum light.  The expansion velocity,
as deduced from the position of the Si II 635.5-nm absorption, is about 12700
km/s.  The Asiago classification spectra are posted at website URL
http://graspa.oapd.inaf.it; classification was made via GELATO (Harutyunyan
et al. 2008, A.Ap. 488, 383) and SNID (Blondin and Tonry 2007, Ap.J. 666,
1024).


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

                         (C) Copyright 2013 CBAT
2013 April 26                    (CBET 3497)              Daniel W. E. Green