Electronic Telegram No. 3424
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 2013ac = PSN J09454879+5840073
     Tianmeng Zhang and Xu Zhou, National Astronomical Observatories of China
(NAOC); and Xiaofeng Wang and Juncheng Chen, Tsinghua University (THU), report
the discovery of an apparent supernova (mag 18.2) on unfiltered CCD images
taken on Feb. 15.70 UT using the 0.6-m NAOC Schmidt telescope in the course of
the THU-NAOC Transient Survey (TNTS).  The new object is located at R.A. =
9h45m08s.79, Decl. = +58d40'07".3 (equinox 2000.0), which is 15" east and 2"
south of the center of the galaxy 2MASX J09450774+5840088.  Nothing is visible
at this position on archival images obtained on Jan. 21 (limiting magnitude
about 20.0) or on a Digitized Sky Survey image from the Palomar Sky Survey.
The TNTS discovery images are posted at the following website URL:
http://www.thca.tsinghua.edu.cn/~wangxf/TNTS/PSNJ09454879+5840073.png.  The
variable was designated PSN J09454879+5840073 (due to an apparent typing
error by the discoverers with 48s.79 instead of 08s.79) when it was posted at
the Central Bureau's TOCP webpage and is here designated SN 2013ac based on
the spectroscopic confirmation reported below.  Additional CCD magnitudes for
2013ac:  Feb. 17.450, 18.2 (Joseph Brimacombe, Cairns, Australia; remotely
using a 51-cm RCOS telescope + luminance filter at the New Mexico Skies
observatory near Mayhill, NM, U.S.A.; position end figures 08s.80, 07".6;
image posted at URL http://www.flickr.com/photos/43846774@N02/8484153372/);
Feb. 18.885, R_c = 18.0 (Massimiliano Martignoni, Magnago, Italy; 0.25-m
reflector; position end figures 08s.71, 09".2); Feb. 19.926, 17.9 (Federica
Luppi and Luca Buzzi, Varese, Italy; 0.38-m f/6.8 reflector; position end
figures 08s.64, 07".3; reference stars from PPMXL catalogue; image posted at
website URL http://www.astrogeo.va.it/pub/TOCP/PSN_J09454879+5840073.jpg).

     Jujia Zhang and Wenbo Xu, Yunnan Astronimical Observatory (YNAO); and
Xulin Zhao and Xiaofeng Wang, Tsinghua University, report on an optical
spectrogram (range 350-880 nm) that was obtained of PSN J09454879+5840073 =
SN 2013ac on Feb. 16.75 UT with the 2.4-m telescope (+ YFOSC) at the LiJiang
Gaomeigu Station of the YNAO.  The spectrum is consistent with a type II-P
supernova a few days after maximum light.  Cross-correlation with a library of
supernova spectra using the "Supernova Identification" code (SNID; Blondin and
Tonry 2007, Ap.J. 666, 1024) shows that 2013ac matches with SN 2005cs at +4
days.


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

                         (C) Copyright 2013 CBAT
2013 February 23                 (CBET 3424)              Daniel W. E. Green