Electronic Telegram No. 3455
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 2013ax IN PGC 20704 = PSN J07200351+5555484
     Li Zhou, Kaicheng Zhang, Xiaofeng Wang, and Juncheng Chen, Tsinghua
University (THU); and Tianmeng Zhang and Xu Zhou, National Astronomical
Observatories of China (NAOC), report the discovery of an apparent supernova
(mag 17.4) on unfiltered CCD images taken on Mar. 7.64 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. = 7h20m03s.51, Decl. = +55d55'48".4 (equinox
2000.0), which is 4".4 east and 5".6 south of the center of the galaxy PGC
20704.   Nothing is visible at this position on archival images obtained on
Feb. 27 (limiting mag about 20.0) or on a Digitized Sky Survey image from the
Palomar Sky Survey.  The TNTS images are posted at the following website URL:
http://www.thca.tsinghua.edu.cn/~wangxf/TNTS/PSNJ07200351+5555484.png.  The
variable was designated PSN J07200351+5555484 when it was posted at the
Central Bureau's TOCP webpage and is here designated SN 2013ax based on the
spectroscopic confirmation reported below.  Additional CCD magnitudes for
2013ax:  Mar. 10.008, 18.2 (Federica Luppi and Luca Buzzi, Varese, Italy;
0.38-m f/6.8 reflector; position end figures 03s.55, 48".5; reference stars
from the USNO-B1.0 catalogue; image posted at the following website URL:
http://www.astrogeo.va.it/pub/TOCP/PSN_P20704.jpg); 10.300, 17.2 (Joseph
Brimacombe, Cairns, Australia; remotely with a 51-cm RCOS telescope +
luminance filter located at the New Mexico Skies observatory near Mayhill,
NM, U.S.A.; position end figures 03s.62, 48".0; image posted at website URL
http://www.flickr.com/photos/43846774@N02/8545669283/).

     Jujia Zhang and Chuanjun Wang, Yunnan Astronomical Observatory (YNAO);
Xulin Zhao and Xiaofeng Wang, Tsinghua University; and Tianmeng Zhang,
National Astronomical Observatories of China, report on an optical spectrogram
(range 350-880 nm) of PSN J07200351+5555484 = SN 2013ax that was obtained on
Mar. 10.57 UT with the 2.4-m telescope (+ YFOSC) at the LiJiang Gaomeigu
Station of the YNAO.  The spectrum is consistent with a type-Ia supernova
around 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 2013ax matches with SN 1994M at +2 days.  Adopting a
recession velocity of 12156 km/s for the host galaxy, PGC 20704 (Falco et al.
1999, PASP 111, 438), they measure the velocity of the Si II 635.5-nm
absorption feature to be about 12300 km/s


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

                         (C) Copyright 2013 CBAT
2013 April 8                     (CBET 3455)              Daniel W. E. Green