[IAUC] CBET 3346: 20121221 : SUPERNOVA 2012hr IN PGC 18880 = PSN J06213846-5942506

Jue Dic 20 22:25:42 ART 2012

                                                  Electronic Telegram No. 3346
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 2012hr IN PGC 18880 = PSN J06213846-5942506
     Colin Drescher, Calamvale, Queensland, Australia, reports the discovery
of an apparent supernova (red mag 14.8) by Peter Marples (Loganholme, Qld.)
on a 30-s unfiltered CCD image (limiting mag 17.5) taken on Dec. 16.53 UT
using a 30-cm Meade LX200R reflector (+ Starlight Xpress camera) in the course
of the Backyard Observatory Supernova Search (BOSS).  The new object is
located at R.A. = 6h21m38s.46, Decl. = -59d42'50".6 (equinox 2000.0; measured
by Drescher), which is 2" west and 94" north of the nucleus of the presumed
host galaxy, ESO 121-26 = PGC 18880.  Nothing is visible at this position on
Digitized Sky Survey red and infrared images (limiting red magnitude > 19).
The variable was designated PSN J06213846-5942506 when it was posted at the
Central Bureau's TOCP webpage and is here designated SN 2012hr based on the
spectroscopic confirmation reported below.  Joseph Brimacombe, Cairns,
Australia, reports magnitude 14.7 and position end figures 38s.49, 51".0
from CCD exposures taken on Dec. 18.565 with a 41-cm RCOS telescope with an
infrared filter (bandpass > 700 nm); his images are posted at website URL
http://www.flickr.com/photos/43846774@N02/8286710122/.

     D. Milisavljevic, Harvard-Smithsonian Center for Astrophysics; R. Fesen,
Dartmouth College; and T. Pickering and A. Kniazev, South African Astronomical
Observatory and Southern African Large Telescope, report that low-dispersion
spectra (range 330-890 nm), obtained on Dec. 19.8 UT with the 10-m SALT
telescope (+ RSS), show PSN J06213846-5942506 = SN 2012hr to be a young
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) shows a reasonable match to SN 2004fu about a week before maximum
light.  After removal of the host-galaxy (ESO 121-26) redshift of z =
0.007562 (via NED; Koribalski et al. 2004, A.J. 128, 16), the absorption
minimum of the Si II 635.5-nm line is found to be blueshifted by about -13700
km/s.

     N. Morrell, M. M. Phillips, C. Contreras, M. Roth, and E. Y. Hsiao, Las
Campanas Observatory; G. H. Marion, Harvard-Smithsonian Center for
Astrophysics; and M. Stritzinger, Aarhus University, on behalf of the Carnegie
Supernova Project, report that a near-infrared spectrum (range 800-2400 nm) of
PSN J06213846-5942506 = SN 2012hr was obtained on Dec. 20.20 UT with the
FoldedPort Infrared Echellette (FIRE) spectrograph on the 6.5-m Magellan Baade
Telescope.  The spectrum shows that 2012hr is a type-Ia supernova
approximately a week before maximum light.  The near-infrared spectrum is
similar to that of SN 2003W at eight days before maximum (Marion et al. 2009,
A.J. 138, 727).  Adopting a redshift of z = 0.008 for the presumed host galaxy
(PGC 18880), the velocity of the Mg II 1092.7-nm absorption feature is
measured to be approximately 12200 km/s.


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

                         (C) Copyright 2012 CBAT
2012 December 21                 (CBET 3346)              Daniel W. E. Green