[IAUC] CBET 3507: 20130508 : SUPERNOVA 2013bz = PSN J13265132-1001322

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                                                  Electronic Telegram No. 3507
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 2013bz = PSN J13265132-1001322
     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; 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 public images from the
Catalina Sky Survey (CSS):

 SN       2013 UT        R.A. (2000.0) Decl.      Mag.      Offset
 2013bz   Apr. 21.28   13 26 51.32  -10 01 32.2   15.7    7".5 E, 5".8 S

The variable was designated PSN J13265132-1001322 when it was posted at the
Central Bureau's TOCP webpage and is here designated SN 2013bz based on the
spectroscopic confirmation reported below.  Additional CCD magnitudes for
2013bz:  Apr. 2.38 UT, [19.5 (CSS); 22.155, 15.4 (L. Elenin, Lyubertsy,
Russia; and I. Molotov, Moscow, Russia; remotely taken with a 0.45-m telescope
at the ISON-NM Observatory near Mayhill, NM, USA; position end figures 51s.09
+/- 0".18, 33".0 +/- 0".19; limiting mag about 18.3; image posted at website
URL http://spaceobs.org/images/TOCP/PSNJ13265132-1001322-20130422.png);
22.234, 14.7 (Joseph Brimacombe, Cairns, Australia; remotely with a 51-cm
RCOS telescope + infrared filter located at the New Mexico Skies observatory
near Mayhill; bandpass > 700 nm; position end figures 51s.12, 32".5; image
posted at URL http://www.flickr.com/photos/43846774@N02/8675516917/).

     T.-W Chen, J. Polshaw, D. Wright, M. Fraser and S. J. Smartt, Queens
University, Belfast; and A. Lawrence, University of Edinburgh, report that a
spectrogram (range 330-975 nm; resolution about 1000) of PSN J13265132-1001322
= SN 2013bz was obtained on Apr. 30.594 UT with the 4.2-m William Herschel
Telescope (+ ISIS).  Cross-correlation with a library of supernova spectra via
the "Supernova Identification" code (SNID; Blondin and Tonry 2007, Ap.J. 666,
1024), and with the redshift fixed to that of the host at z = 0.019, suggests
a normal type-Ia supernova around maximum light.  Given the host redshift and
the reported photometry, the absolute magnitude of the supernova is between
-19.0 and -19.7, at around 8 days prior to the acquisition of the spectrum.
This could be over-luminous for a normal type-Ia event, but the uncertainties
in the reported magnitudes preclude a conclusion.  The spectrum can also be
fitted with a 1991T-like template a week after maximum, but that requires a
redshift of z = 0.015.  Further photometry and spectroscopy would be required
to determine the epoch and luminosity of 2013bz.


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

                         (C) Copyright 2013 CBAT
2013 May 8                       (CBET 3507)              Daniel W. E. Green