Electronic Telegram No. 2414
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
CBAT Director:  Daniel W. E. Green; Room 209; Dept. of Earth and Planetary
 Sciences; Harvard University; 20 Oxford St.; Cambridge, MA  02138; U.S.A.
e-mail:  cbat@iau.org; cbatiau@eps.harvard.edu
URL http://www.cfa.harvard.edu/iau/cbat.html


SUPERNOVA 2010gy
     R. Chornock, Harvard-Smithsonian Center for Astrophysics (CfA); M. Huber,
Johns Hopkins University (JHU); R. J. Foley, M. Brodwin, and J. Ruel, CfA;
A. Rest, Space Telescope Science Institute; G. Narayan, E. Berger, P. Challis,
R. P. Kirshner, A. M. Soderberg, and C. Stubbs, CfA; M. Fraser and S. J. Smartt
Queen's University, Belfast; Y. Urata, National Central University, Jung-Li;
J. Tonry, Institute for Astronomy (IfA); A. Riess, JHU; W. M. Wood-Vasey,
University of Pittsburgh; P. A. Price, Princeton University; and E. Magnier, K.
Chambers, N. Kaiser, J. Morgan, W. Burgett, J. Heasley, W. Sweeney, C. Waters,
and H. Flewelling, IfA, report the discovery of a low-redshift type-Ia
supernova in the Pan-STARRS1 Medium Deep Survey.  The object (designated
PS1-1000385 with the survey) was discovered at g = 20.8 (AB magnitude) on Aug.
5.59 UT at R.A. = 2h27m12s.036, Decl. = -4d32'04".87 (equinox 2000.0).  The
previous non-detection had a 3-sigma upper limit of magnitude z = 23.0 on July
30.6.  The transient has subsequently risen in brightness to magnitude g =
18.4 on Aug. 14.6.  No clear host galaxy is associated with this transient.
The nearest object present in either the PS1 images or archival Canada-France-
Hawaii Telescope imaging is the source VVDS 20208952 (magnitude g = 24.5; see
http://vizier.cfa.harvard.edu/viz-bin/VizieR-5?-out.add=.&-source=II/286/
vcat&VVDS=20208952).
     A spectrum (range 340-860 nm) was obtained on Aug 14.4 using IMACS on
the Magellan Baade 6.5-m telescope, which revealed the transient to be a
normal type-Ia supernova near maximum light.  Cross-correlation with a library
of supernova template spectra using the SNID program (Blondin and Tonry 2007,
ApJ, 666, 1024) finds a best-fit redshift of z = 0.06 and an age of 2 (+/- 3)
days before maximum light.  The true host galaxy remains uncertain and is
either a very low-luminosity dwarf galaxy or is located far from the supernova.
     The PS1 and Magellan telescope staffs are thanked for their assistance
with these observations.  This discovery was enabled using the PS1 System,
operated by the PS1 Science Consortium (PS1SC) and its member institutions,
and made possible through the PS1 Builders (see the following website URL
http://www.ps1sc.org/PS1_System_IAU.shtml).


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

                         (C) Copyright 2010 CBAT
2010 August 17                   (CBET 2414)              Daniel W. E. Green