[IAUC] CBET 2783: 20110809 : SUPERNOVA 2011ek NEAR NGC 918 = PSN J02254889+1832000

[quai en eps.harvard.edu]

                                                  Electronic Telegram No. 2783
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 2011ek NEAR NGC 918 = PSN J02254889+1832000
     S. Nakano, Sumoto, Japan, reports the discovery by Koichi Itagaki
(Teppo-cho, Yamagata, Japan) of an apparent supernova (mag 16.4)
on a unfiltered CCD frames (limiting mag 19.0) taken on Aug. 4.77 UT using
a 0.60-m f/5.7 reflector (+ BITRAN BT-21 camera).  The new object is located
at R.A. = 2h25m48s.89, Decl. = +18d32'00".0 (equinox 2000.0), which is 27"
west and 133" north of the center of NGC 918.  Nothing is visible at this
position on the Digitized Sky Survey (limiting mag about 20; no bandpass or
date provided).  The discovery image has been posted at the following website
URL:  http://www.k-itagaki.jp/images/psn-ngc918.jpg.  The variable was
designated PSN J02254889+1832000 when posted at the Central Bureau's TOCP
webpage and is here designated SN 2011ek based on the spectroscopic report
below.  Additional unfiltered CCD magnitudes for 2011ek:  2008 Dec. 1.601,
[19.5 (Itagaki; communicated by Nakano); Aug. 5.406, 16.4 (Joseph Brimacombe,
Cairns, Australia; position end figures 48s.89, 32'00".0); 5.62, 16.0
(Itagaki; communicated by H. Yamaoka, Kyushu University); 5.64, 16.3
(Toshihide Noguchi, Katori, Chiba-ken, Japan; 0.23-m Schmidt-Cassegrain
reflector + BITRAN BT-11E camera; communicated via Nakano; position end
figures 48s.92, 31'59".3; limiting mag 17.5); 6.642, 15.8 (Itagaki;
communicated by Yamaoka); 7.73, 16.6 (K. Kadota, Ageo, Japan; 0.25-m f/5
reflector + SBIG ST-9E camera; communicated via Nakano; position end
figures 48s.88, 31'59".5; limiting mag 18.0); 8.735, 16.1 (M. Tsuboi,
Hiroshima, Japan; communicated by Nakano).  Kadota's image is located at
http://members.jcom.home.ne.jp/kenic-k/image/PSNinNGC918-20110807.jpg.

     D. D. Balam, Dominion Astrophysical Observatory, National Research
Council of Canada (NRCC); M. L. Graham, Las Cumbres Observatory Global
Telescope, University of California at Santa Barbara; E. Y. Hsiao,
Lawrence Berkeley Laboratory; and D. W. E. Green, Harvard University,
report that a spectrogram (range 383-717 nm, resolution 0.3 nm) of PSN
J02254889+1832000 = 2011ek, obtained on Aug. 7.41 UT with the 1.82-m
Plaskett Telescope of the NRCC, shows it to be a type-Ia supernova
before maximum light.  Comparison with a library of supernova spectra
using the "superfit" matching program of Howell et al. (2005, Ap.J. 634,
1190) indicates that 2011ek is a normal type-Ia supernova most similar
to SN 2002bo at 11 days before maximum light.


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

                         (C) Copyright 2011 CBAT
2011 August 9                    (CBET 2783)              Daniel W. E. Green