[IAUC] CBET 2871: 20111025 : SUPERNOVA 2011gy IN UGC 2756 = J03293530+4052029

Mar Oct 25 01:18:31 ART 2011

                                                  Electronic Telegram No. 2871
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 2011gy IN UGC 2756 = J03293530+4052029
     Zhangwei Jin (Ningbo, Zhejiang, China) and Xing Gao (Urumqi, Xinjiang,
China) report the discovery of a possible supernova (mag approximately 15.8)
on a 40-s unfiltered CCD survey image (limiting mag about 19.5) taken by Xing
Gao in the course of the Xingming Observation Sky Survey around Oct. 22.795 UT
using a 0.35-m f/6.9 Celestron C14 Schmidt-Cassegrain telescope.  The new
object is approximately located at R.A. = 3h29m35s.30, Decl. = +40d52'02".9
(equinox 2000.0), which is about 2".3 east and 5".1 south of the center of the
galaxy UGC 2756 = MCG +7-8-15 = PGC 12982.  Nothing is visible at this position
on archival images taken at Mt. Nanshan on Oct. 6 (limiting mag 19.0) and 8
(limiting mag 19.5) or on a Digitized Sky Survey red plate from 1989 Sept. 29
(limiting mag about 19.8).  Their images have been posted at the following
website URL:  http://www.xjltp.com/XOSS/XM24ZJ/XM24ZJ.htm.  The variable was
designated as PSN J03293530+4052029 when it was posted on the Central Bureau's
TOCP webpage and is here designated SN 2011gy based on the spectroscopic
confirmation reported below.
     Additional unfiltered CCD magnitudes for 2011gy:  Oct. 23.211 UT, 15.5
(R. A. Koff, Bennett, CO, USA; Meade 0.25-m f/10 reflector + Apogee AP-47p CCD
camera; position end figures 35s.30, 03".4; UCAC3 reference stars; limiting
magnitude 18.2); 23.287, 16.1 (Joseph Brimacombe, Cairns, Australia; position
end figures 35s.27, 03".8); 23.500, 15.4 (C. Jacques and E. Pimentel, Belo
Horizonte, Brazil; remotely using the GRAS G11 telescope in New Mexico, USA;
position end figures 35s.34, 03".0; UCAC2 reference stars; limiting magnitude
18.5; image posted at website URL http://ceamig-rea.net/tocp/P12982_tocp.jpg).

     S. Taubenberger and M. Klauser, Max-Planck-Institut fuer Astrophysik;
S. Hachinger, S. Benetti, and S. Valenti, Istituto Nazionale di Astrofisica,
Osservatorio Astronomico di Padova; and M. Fiaschi, Dipartimento di Astronomia,
Universita di Padova, on behalf of a larger collaboration, report that a
spectrum of PSN J03293530+4052029 = SN 2011gy, obtained on Oct. 23.92 UT with
the Ekar-Copernico 1.82-m Telescope (+ AFOSC; range 350-810 nm, resolution 2.4
nm) shows it to be a normal type-Ia supernova a few days before maximum light.
Cross-correlation with a library of supernova spectra using GELATO (Harutyunyan
et al. 2008, A.Ap. 488, 383; publicly available at https://gelato.tng.iac.es)
yields a best match with spectra of SN 1998bu at half a week to one week before
maximum light.  Adopting a recession velocity 5061 km/s for MCG +7-8-15 (Emilio
et al. 1999, PASP 111, 438; via NED), the expansion velocity measured from the
Si II 635.5-nm line is about 12000 km/s.

     T. Zhang, National Astronomical Observatories of China (NAOC); J. Chen,
and X. Wang, Tsinghua Center for Astrophysics, Tsinghua University; and L. Lin
and X. Kong, University of Science and Technology of China, report on an
optical spectrogram (range 350-820 nm) of PSN J03293530+4052029 = SN 2011gy
that was obtained on Oct. 24.73 UT with the 2.16-m telescope (+ OMR) at the
Xinglong Station of the NAOC.  The spectrum is consistent with a type-Ia
supernova at about one week before maximum light.  After removal of the host-
galaxy recession velocity of about 5061 km/s (from NED), they find the
absorption minimum of the Si II 635.5-nm line to be blueshifted by about 12000
km/s.  Cross-correlation with a library of supernova spectra using the
"Supernova Identification" code (SNID; Blondin and Tonry 2007, Ap.J. 666,
1024) shows that 2011gy matches with SN 2002er at -6 days.


NOTE: These 'Central Bureau Electronic Telegrams' are sometimes
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                         (C) Copyright 2011 CBAT
2011 October 25                  (CBET 2871)              Daniel W. E. Green