Electronic Telegram No. 2870
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 2011gx IN ESO 252-G10 = TCP J05060576-4503003
     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; R. H. McNaught and G. Garradd, Australian National University; 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 public images from the Siding Spring Survey (SSS).

 SN       2011 UT       R.A. (2000.0) Decl.      Mag.      Offset
 2011gx   Oct. 3.69    5 06 05.76  -45 03 00.3   18.3    41".5 W, 10".7 S

Nothing was visible at this position on a SSS image from Mar. 5.52 UT
(limiting mag 19.5).  The object was designated TCP J05060576-4503003 when it
was posted on the Central Bureau's TOCP webpage and is here designated SN
2011gx based on the spectroscopic confirmation reported below.  Infrared CCD
magnitudes (filter bandpass > 700 nm) for 2011gx by Joseph Brimacombe, Cairns,
Australia:  Oct. 5.584, 16.8 (position end figures 05s.76, 00".7); 6.701, 16.6
(image posted at URL http://www.flickr.com/photos/43846774@N02/6218866501/);
8.780, 16.7; 9.638, 16.5; 10.769, 16.6; 12.675, 16.6 (image posted at website
URL http://www.flickr.com/photos/43846774@N02/6238615803/).

     P. Ochner, S. Valenti, S. Benetti, A. Pastorello, and L. Tomasella,
Istituto Nazionale di Astrofisica (INAF), Osservatorio Astronomico di Padova;
and F. Bufano, INAF, Osservatorio Astronomico di Catania, on behalf of a
larger collaboration, report that a spectrum of TCP J05060576-4503003 = SN
2011gx, obtained on Oct. 18.17 UT with the New Technology Telescope (+ EFOSC2;
range 360-930 nm; resolution 1.8 nm) shows it to be a type-II supernova.  The
best fit to this spectrum found by GELATO (Harutyunyan et al. 2008, A.Ap. 488,
383; publicly available at https://gelato.tng.iac.es) is with spectra of type-
II-plateau supernovae at about one month post-explosion.  Together with the
classical P-Cyg Balmer features, prominent lines of Ca II, Fe II, and Na I D
are detected.  Adopting a recessional velocity of 9821 km/s for ESO 252-G10
(Lauberts and Valentijn, 1989, THE SURFACE PHOTOMETRY CATALOGUE OF THE ESO-
UPPSALA GALAXIES, European Southern Obsrvatory) the expansion velocity
deduced from the H_alpha absorption is about 8000 km/s.


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      superseded by text appearing later in the printed IAU Circulars.

                         (C) Copyright 2011 CBAT
2011 October 22                  (CBET 2870)              Daniel W. E. Green