[IAUC] CBET 2858: 20111004 : SUPERNOVA 2011gr = PSN J00204598+0656052

Mar Oct 4 01:05:04 ART 2011

                                                  Electronic Telegram No. 2858
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 2011gr = PSN J00204598+0656052
     [Editor's note:  the best below replaces that on CBET 2857.]
     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; E. C. Beshore and S. M.
Larson, Lunar and Planetary Laboratory, University of Arizona; and E.
Christensen, Gemini Observatory, report the discovery of an apparent supernova
in unfiltered Catalina Sky Survey (CSS) images:

 SN       2011 UT       R.A. (2000.0) Decl.      Mag.      Offset
 2011gr   Sep. 18.45   0 20 45.98  + 6 56 05.2   18.3    21".7 E, 2".4 N

This variable was designated PSN J00204598+0656052 when it was posted on the
Central Bureau's TOCP webpage and is here designated SN 2011gr based on the
spectroscopic report below.  Further CCD magnitudes for 2011gr, unfiltered
unless otherwise noted:  June 28.46 UT, [20.0 (CSS); Sept. 19.468, 18.7 (J.
Brimacombe, Cairns, Australia; position end figures 45s.95, 05".1; image
posted at website URL http://www.flickr.com/photos/43846774@N02/6166997171/);
Oct. 2.092, R = 18.9 (Federica Luppi, Varese, Italy, 0.36-m f/7.9 reflector
+ Bessell R filter; position end figures 45s.94, 04".8; CMC-14 reference
stars; image posted at http://www.astrogeo.va.it/pub/TOCP/PSN_P1310401.jpg).

     F. Bufano, Istituto Nazionale di Astrofisica (INAF), Osservatorio
Astronomico di Catania; S. Benetti, S. Valenti, L. Tomasella, and P. Ochner,
INAF, Osservatorio Astronomico di Padova; and A. Pastorello, Dipartimento di
Astronomia, Universita di Padova, on behalf of a larger collaboration, report
that a spectrogram of PSN J00204598+0656052 = = SN 2011gr, obtained by the
Service Telescope Operator Team on Sept. 28.8 UT with the Ekar-Copernico
1.82-m telescope (+ AFOSC; range 360-810 nm; resolution 2.2 nm), is that of a
type-Ia supernova.  Cross-correlation with a library of supernova spectra
using the "Supernova Identification" code (SNID; Blondin and Tonry 2007, Ap.J.
666, 1024) suggests a normal type-Ia supernova about three weeks after its
B-band maximum at a redshift z = 0.07.  The expansion velocity derived from
the Si II 635.5-nm minimum is then about 9000 km/s.

     L. Magill and R. Kotak, Queen's University, Belfast, report that an
optical spectrogram (range 350-900 nm) of PSN J00204598+0656052 = SN 2011gr was
obtained at the Nordic Optical Telescope (+ ALFOSC) by M. B. Nielsen on Sept.
28.97 UT; cross-correlatation with a library of supernova spectra using the
SNID software yields a best fit was with a type-Ia supernova, being similar to
SN 2003du at epochs of 20-22 days (Anupama et al. 2005, A.Ap. 429, 667).
Fitting with SNID yields a redshift of 0.068.


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

                         (C) Copyright 2011 CBAT
2011 October 4                   (CBET 2858)              Daniel W. E. Green