[IAUC] CBET 3599: 20130724 : SUPERNOVA 2013ef IN UGC 1395

[quai en eps.harvard.edu]

                                                  Electronic Telegram No. 3599
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 2013ef IN UGC 1395
     K. Z. Stanek, B. J. Shappee, C. S. Kochanek, J. Jencson, U. Basu, T.
Holoien, and J. F. Beacom, Ohio State University, J. L. Prieto, Princeton
University; D. Szczygiel and G. Pojmanski, Warsaw University Observatory; and
M. Dubberley, M. Elphick, S. Foale, E. Hawkins, D. Mullens, W. Rosing, R.
Ross, and Z. Walker, Las Cumbres Observatory, report the discovery of an
apparent supernova during the ongoing All Sky Automated Survey for SuperNovae
(ASAS-SN or "Assassin"), using data from the double 14-cm "Brutus" telescope
at Haleakala, Hawaii.

 SN       2013 UT       R.A. (2000.0) Decl.      Mag.      Offset
 2013ef   July 4.56    1 55 20.71  + 6 36 35.3   16.1    19" W, 7" S

Nothing is visible at this position (limiting V magnitude 17) on images taken
June 27 and earlier, though there was detection in two images on July 4 and a
likely detection on July 1.  Additional ASAS-SN V-band magnitudes for 2013ef:
July 8, 16.0; 12, 16.1; 15, 16.2; 18, 16.3.  The discovery image is posted at
URL http://www.astronomy.ohio-state.edu/~assassin/followup/asassn13bb.jpg,
where the top-left panel shows the reference image, the top-right panel shows
the Digitized Sky Survey image at the same angular scale, the lower-left panel
is one of the 90-s V-band images from July 4, and the lower-right panel is the
image-subtraction residual image on July 4.  UGC 1395 is a Seyfert 2 galaxy
and the subject of many previous observations, including with the Hubble Space
Telescope.  Information on the ASAS-SN project is posted at website URL
http://www.astronomy.ohio-state.edu/~assassin/index.shtml.

     M. Childress, R. Scalzo, F. Yuan, and B. Schmidt, Australian National
University (ANU); and B. Tucker, ANU and University of California at Berkeley,
report that spectroscopy of 2013ef shows it to be a type-Ia supernova near
maximum light.  A 40-min spectrogram was obtained on July 4.79 UT with the
Wide Field Spectrograph (WiFeS; cf. Dopita et al. 2007, Ap. Space Sci. 310,
255) on the ANU 2.3-m telescope at Siding Spring, using the B3000/R3000
gratings (wavelength range 350-980 nm at 0.1-nm resolution).  The supernova
spectrum shows clear signatures of a type-Ia supernova at maximum light,
including strong absorption of Si II 635.5- and 597.2-nm, and the Ca II
near-infrared triplet and H and K lines.  Classification with SNID (Blondin
and Tonry 2007, Ap.J. 666, 1024) shows good matches to type-Ia supernovae near
maximum light.  The best match is to SN 2002er at one day before maximum light
and redshift of 0.015, consistent with redshift of the apparent host galaxy,
UGC 1395 (z = 0.017405, from Mahdavi and Gellar 2004, Ap.J. 607, 202).


NOTE: These 'Central Bureau Electronic Telegrams' are sometimes
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                         (C) Copyright 2013 CBAT
2013 July 24                     (CBET 3599)              Daniel W. E. Green