Electronic Telegram No. 3539
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 2013ct IN NGC 428 = PSN J01125492+0058457
     Stuart Parker, Canterbury, New Zealand, reports the discovery of an
apparent supernova (red mag 12.2) on a 40-s unfiltered CCD image (limiting
mag 16) taken by himself on May 10.773 UT with a 30-cm Astro-Tech AT12RC
Ritchey-Chretien astrograph (+ ST10 camera) at his Parkdale Observatory in the
course of the Backyard Observatory Supernova Search.  The new object is
located at R.A. = 1h12m54s.92, Decl. = +0d58'45".7 (equinox 2000.0; reference
stars from USNO-B and UCAC3 catalogues), which is 11" west and 8" north of the
nucleus of the galaxy NGC 428.  Nothing is visible at this position on
Digitized Sky Survey red and infrared images (limiting red magnitude > 19).
An image of the variable was posted by Parker at  http://tinyurl.com/d9xo4ol.
The variable was designated PSN J01125492+0058457 when it was posted at the
Central Bureau's TOCP webpage and is here designated SN 2013ct based on the
spectroscopic confirmation reported below.  Additional CCD magnitudes for
2013ct:  May 11.398, V = 12.14 +/- 0.01 (Arto Oksanen and Caisey Harlingten;
using an 0.5-m PlaneWave CDK telescope + Apogee Alta U42 camera located at
San Pedro de Atacama, Chile; position end figures 55s.00, 47".7); 11.401, B
= 12.51 +/- 0.01 (Oksanen and Harlingten; image posted at website URL
http://pilvi.dyndns.org/arto/PSNJ01125492+0058457_20130511B.jpg); 11.407, L
= 12.0, B = 11.7, R = 12.4 (Alain Maury and Andrew Blanchard, 40-cm f/5.6
telescope + Apogee U16 CCD camera; variable at altitude 14 deg; observing
site not specified); 27.806, 12.8 (Joseph Brimacombe, Cairns, Australia;
41-cm telescope + infrared filter bandpass > 700 nm; position end figures
54s.98, 47".3).  Brimacombe's images are posted at the following website
URL:  http://www.flickr.com/photos/43846774@N02/8861109595/.

     E. Y. Hsiao, Las Campanas Observatory, reportS that a near-infrared
spectrogram (range 800-2400 nm) of PSN J01125492+0058457 = SN 2013ct
was obtained on May 22.42 UT with the FoldedPort Infrared Echellette (FIRE)
spectrograph on the 6.5-m Magellan Baade Telescope.  The spectrum shows
that 2013ct is a type-Ia supernova at 2-3 weeks past maximum light.  The
near-infrared spectrum is similar to that of SN 2001en at 18 days past
maximum (Marion et al. 2009, A.J. 138, 727).  The supernova redshift
approximately matches the redshift of the presumed host galaxy (NGC 428)
at z = 0.003843.


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

                         (C) Copyright 2013 CBAT
2013 June 2                      (CBET 3539)              Daniel W. E. Green