Electronic Telegram No. 3661
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 2013fm IN PGC 21194 = PSN J07310540+5756108
     Denis Denisenko, Sternberg Astronomical Institute, reports the discovery
by P. Balanutsa of an apparent supernova on 60-s unfiltered CCD survey images
obtained on Sept. 6.778 and 6.814 UT (with measured magnitudes 17.0 and 16.7,
and limiting magnitudes 18.5 and 18.1, respectively) with the 0.40-m f/2.5
MASTER-Amur reflector.  The new object is located at R.A. = 7h31m05s.40, Decl.
= +57d56'10".8 (equinox 2000.0), which is 7" west and 11" south of the nucleus
of the galaxy PGC 21194 = MCG +10-11-68.  The discovery and reference images
are posted at URL http://master.sai.msu.ru/static/OT/073105.40575610.8.png.
The variable was designated PSN J07310540+5756108 when it was posted at the
Central Bureau's TOCP webpage and is here designated SN 2013fm based on the
spectroscopic confirmation reported below.  Additional CCD magnitudes for
2013fm:  2012 Oct. 20.735, [18.9 (MASTER-Amur); 2013 Sept. 8.086, 16.3 (Denis
Buczynski, Portmahomack, U.K.; Celestron C14 telescope + ST9XE camera;
position end figures 05s.34, 11".0; UCAC-3 reference stars); 8.091, 18.5
Gianluca Masi, Francesca Nocentini, and Patrick Schmeer, remotely using a
43-cm robotic telescope at Ceccano, Italy; position end figures 05s.34,
11".1); 8.477, 18.0 (Joseph Brimacombe, Cairns, Australia; remotely using a
51-cm RCOS and STL11K camera + luminance filter at the New Mexico Skies
Observatory near Mayhill, NM, USA; position end figures 05s.38, 10".9; image
posted at website URL http://www.flickr.com/photos/43846774@N02/9703959135/);
11.661, 17.6 (MASTER-Amur; image posted at the following website URL:
http://master.sai.msu.ru/static/OT/J07310540+5756108-Sep11-MASTER-Amur.jpg).

     Jun Mo, Xulin Zhao, and Xiaofeng Wang, Tsinghua University (THU); and
Tianmeng Zhang, National Astronomical Observatories of China (NAOC), report
on an optical spectrogram (range 390-870 nm) of PSN J07310540+5756108 = SN
2013fm that was obtained on Sept. 25.83 UT with the 2.16-m telescope (+ OMR)
at the Xinglong Station of the NAOC.  The spectrum is consistent with that of
a type-Ia supernova about one month 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 2013fm matches with
SN 1991M at +28 days.  Adopting a redshift of 0.042 for the host galaxy, MCG
+10-11-68 (after Rines et al. 2000, A.J. 120, 2338), they measure the velocity
of the Si II 635.5-nm absorption feature to be about 10300 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 October 1                   (CBET 3661)              Daniel W. E. Green