Electronic Telegram No. 3316
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 2012gy = PSN J07563555+3954072
     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. C. Beshore, S. M. Larson, and E. Christensen, Lunar
and Planetary Laboratory, University of Arizona, report the discovery of an
apparent supernova in public images from the Catalina Sky Survey (CSS).

 SN       2012 UT        R.A. (2000.0) Decl.     Mag.      Offset
 2012gy   Nov. 15.36   7 56 35.55  +39 54 07.2   18.2    1".8 W, 2".2 N

The variable was designated PSN J07563555+3954072 when it was posted at the
Central Bureau's TOCP webpage and is here designated SN 2012gy based on the
spectroscopic confirmation reported below.  Additional CCD magnitudes for
2012gy:  Oct. 25.37, [19.5 (CSS); Nov. 17.378, 17.4 (Joseph Brimacombe,
Cairns, Australia; luminance filter; position end figures 35s.71, 05".5; image
posted at website URL http://www.flickr.com/photos/43846774@N02/8194687251);
21.009, R = 17.2 (J. Nicolas, Vallauris, France; 0.41-m f/3.3 reflector;
position end figures 35s.71, 05".6); 21.195, 18.0 (Federica Luppi and Luca
Buzzi, Varese, Italy; position end figures 35s.71, 05".1; image posted at URL
http://www.astrogeo.va.it/pub/TOCP/PSN_J07563555+3954072.jpg).

     T.-W. Chen, R. Kotak, M. Fraser, and S. J. Smartt, Queen's University,
Belfast; M. Sullivan, University of Southampton; and K. Maguire, Oxford
University, report that a spectrogram (range 330-975 nm; resolution about 500)
of PSN J07563555+3954072 = SN 2012gy was obtained on Nov. 22.23 UT with the
4.2-m William Herschel Telescope (+ ISIS).  From narrow H-alpha emission,
they determine a redshift of 0.067 for 2012gy.  Cross-correlation with a
library of supernova spectra via the "Supernova Identification" code (SNID;
Blondin and Tonry 2007, Ap.J. 666, 1024) gives a best match for 2012gy with
the interacting type-Ia supernova 2002ic about a week after maximum light.
They measure a minimum for the Si II 615.0-nm feature of 11000 km/s.
     The weak (8 x 10**-16 erg/s/A) but real feature that they attribute to
H-alpha has a FWHM of about 1.4 nm, which is the same as that of the narrow
night-sky lines, suggesting that H-alpha is unresolved.  This is in contrast
to the broader H-alpha, which was seen in the prototypical interacting
type-Ia supernova 2002ic.  The authors note, however, that spatially extended
H-alpha emission is not visible in the two-dimensional spectrum.  Finally, a
double-notched feature at around 400.0 nm rest frame is consistent with a
super-Chandrasekhar explosion, which would make the detection of a H-rich
circumstellar medium even more peculiar.


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

                         (C) Copyright 2012 CBAT
2012 November 27                 (CBET 3316)              Daniel W. E. Green