Electronic Telegram No. 3466
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 2013bb IN NGC 5504 = PSN J14121396+1550315
     S. Howerton, Arkansas City, KS, U.S.A.; A. J. Drake, S. G. Djorgovski,
A. Mahabal, M. J. Graham, and R. Williams, California Institute of Technology;
J. L. Prieto, Princeton University; M. Catelan, Pontificia Universidad
Catolica de Chile; R. H. McNaught, Australian National University; 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 public images from the Catalina Sky Survey (CSS):

 SN       2013 UT        R.A. (2000.0) Decl.      Mag.      Offset
 2013bb   Apr. 3.42   14 12 13.96  +15 50 31.5    18.4    26".7 W, 0".6 N

The variable was designated PSN J14121396+1550315 when it was posted at the
Central Bureau's TOCP webpage and is here designated SN 2013bb based on the
spectroscopic confirmation reported below.  Additional CCD magnitudes for
2013bb:  Apr. 4.317 UT, 18.1 (Joseph Brimacombe, Cairns, Australia; luminance
filter used; no instrumentation provided; position end figures 14s.05, 30".9;
image posted at URL http://www.flickr.com/photos/43846774@N02/8621423988/);
4.378, 18.2 (L. Elenin, Lyubertsy, Russia; and I. Molotov, Moscow, Russia;
remotely taken with a 0.45-m f/2.8 telescope at the ISON-NM Observatory near
Mayhill, NM, USA; position end figures 14s.11 +/- 0".07, 31".9 +/- 0".08;
UCAC-4 reference stars; limiting mag about 20.5; image posted at website URL
http://spaceobs.org/images/TOCP/PSNJ14121396+1550315-20130404.png); 10.37,
18.1 (CSS).

     N. Elias-Rosa and A. Morales-Garoffolo, Institut de Ciencies de l'Espai,
IEEC, Consejo Superior de Investigaciones Cientificas, Barcelona; S.
Taubenberger, Max-Planck-Institut fuer Astrophysik, Garching; S. Hachinger,
University of Wuerzburg; E. S. Walker, Yale University; M. Fraser, Queen's
University, Belfast; S. Benetti and A. Pastorello, Istituto Nazionale di
Astrofisica, Padova Astronomical Observatory; S. Valenti, University of
California at Santa Barbara and Las Cumbres Observatory Global Telescope; S.
J. Smartt, K. Smith, D. Young, and M. Fraser, Queen's University, Belfast; M.
Sullivan, University of Southampton; and A. Gal-Yam and O. Yaron, Weizmann
Institute for Science, on behalf of the PESSTO collaboration (see Valenti et
al., as posted at website URL http://www.astronomerstelegram.org/?read=4037),
report that optical spectroscopy (range 390-920 nm), obtained on Apr. 6.26 UT
with the New Technology Telescope (+ EFOSC2), show that PSN J14121396+1550315
= SN 2013bb is a young type-IIb supernova.  The supernova spectrum strongly
resembles that of SN 2003bg (Hamuy et al. 2009, Ap.J. 703, 1612) at one week
before maximum.  A relatively strong H_alpha P-Cyg line is seen with an
absorption blueshift of about 14500 km/s; the He I 587.6-nm line appears
at a blueshift of about 11500 km/s.  The host galaxy, NGC 5504, has a
redshift z of about 0.0175 (via http://nedwww.ipac.caltech.edu).  PESSTO
classification spectra can be found at website URL http://www.pessto.org/;
the classification was made via 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 13                    (CBET 3466)              Daniel W. E. Green