Electronic Telegram No. 3518
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 2013ch IN ESO 7-6 = PSN J12414341-8427524
     Greg Bock, Windaroo, Queensland, Australia, reports the discovery of an
apparent supernova (red mag 16.9) on a 30-s unfiltered CCD image (limiting mag
17.5) taken by Peter Marples (Loganholme, Queensland, Australia) on Apr. 30.46
UT with a 30-cm Meade LX200R reflector (+ SXVR-H9 Starlight Xpress camera)
in the course of the Backyard Observatory Supernova Search.  The new object is
located at R.A. = 12h41m43s.41, Decl. -84d27'52".4 (equinox 2000.0; reference
stars from USNO-B and UCAC4 catalogues), which is 33".9 west and 2".3 north of
the nucleus of the galaxy ESO 7-6.  Nothing is visible at this position on
Digitized Sky Survey red and infrared images (limiting red magnitude > 19).
The variable was designated PSN J12414341-8427524 when it was posted at the
Central Bureau's TOCP webpage and is here designated SN 2013ch based on the
spectroscopic confirmation reported below.

     J. Parrent, Las Cumbres Observatory Global Telescope (LCOGT) and
Dartmouth College; D. Milisavljevic, Harvard-Smithsonian Center for
Astrophysics; and M. L. Graham, S. Valenti, and D. A. Howell, LCOGT and
University of California at Santa Barbara, write that a CCD spectrogram (range
350-900 nm) was taken of PSN J12414341-8427524 = SN 2013ch with the Gemini
South telescope (+ Gemini Multi-Object Spectrograph, GMOS) on May 6.9 UT.  The
spectrum reveals a continuum superimposed with Balmer series and He I P-Cyg
profiles, indicative of a type-IIb supernova.  Assuming a redshift of z =
0.0073, based on narrow emission lines from the host galaxy (ESO 7-6), the
H-alpha absorption feature is blueshifted by about 17000 km/s.  The authors
estimate the epoch to be near maximum light, based on comparisons to other
spectra using "Superfit" (Howell et al. 2005, Ap.J. 634, 1190), and find that
it most closely matches SN 1993J (Barbon et al. 1995, A.Ap. Suppl. 110, 513).
They also estimated the B-band apparent magnitude as about 17 on May 2 UT,
using the Cerro Tololo LSC 1-m telescope.


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      superseded by text appearing later in the printed IAU Circulars.

                         (C) Copyright 2013 CBAT
2013 May 12                      (CBET 3518)              Daniel W. E. Green