[IAUC] CBET 3375: 20130107 : SUPERNOVA 2013C IN PGC 33561 = PSN J11055522+7231203

Dom Ene 6 22:02:00 ART 2013

                                                  Electronic Telegram No. 3375
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 2013C IN PGC 33561 = PSN J11055522+7231203
     S. Nakano, Sumoto, Japan, reports the discovery by Masaki Tsuboi
(Kuchita-minami, Asakita-ku, Hiroshima) of an apparent supernova (mag 16.5)
on a 40-s unfiltered CCD frame (limiting mag 18.4) taken on Jan. 4.776 UT
using a 0.30-m f/5.3 reflector (+ ST-9XE camera) and confirmed on 35 frames
taken during about one hour after the discovery image.  The new object is
located at R.A. = 11h05m55s.22, Decl. = +72d31'20".3 (equinox 2000.0), which
is 5".1 west and 11".4 south of the center of the galaxy PGC 33561.  Nothing
is visible at this position on a Digitized Sky Survey image (limiting red mag
19 or fainter).  Tsuboi has posted his discovery image at the following URL:
http://tenku.dee.cc/PSN/P33561130105-11.jpg.  The variable was designated PSN
J11055522+7231203 when it was posted at the Central Bureau's TOCP webpage and
is here designated SN 2013C based on the spectroscopic confirmation reported
below.  Additional CCD magnitudes for 2013C (unfiltered unless otherwise
noted):  2012 Nov. 3.752, [17.6 (Tsuboi); 2013 Jan. 4.955, 16.0 (Giancarlo
Cortini, Predappio, Italy; 0.35-m reflector; limiting mag 19.5); 5.014, 15.9
(T. Yusa, Osaki, Japan; remotely using the iTelescope T18, a 0.32-m f/8.0
astrograph, at the RAS observatory near Nerpio, Spain; position end figures
55s.21, 20".1; UCAC-3 reference stars; limiting mag 19.0; images posted at
URL http://space.geocities.jp/yusastar77/supernova/PSNinP33561_130105.htm);
5.087, R_c = 16.7 (Massimiliano Martignoni, Magnago, Italy; 0.25-m reflector;
position end figures 55s.25, 20".7); 5.589, 16.2 (Toshihide Noguchi, Katori,
Chiba-ken, Japan; 0.23-m f/6.3 reflector + BITRAN BT-11E camera; limiting mag
18.0; position end figures 55s.31, 20".1; position end figures of galaxy
center 56s.44, 31".3; UCAC3 reference stars; communicated by Nakano; image
posted at website URL http://park8.wakwak.com/~ngc/images/PSNinP33561.jpg);
5.681, 16.1 (K. Kadota, Ageo, Saitama-ken, Japan; 0.25-m reflector + SBIG
ST-9E camera; position end figures 55s.24, 20".6; galaxy center position end
figures 56s.20, 32".8; limiting mag 19.2; communicated by Nakano; image posted
at http://members.jcom.home.ne.jp/kenic-k/image/PSNinPGC33561-20130105.jpg).

     K. Ayani, Bisei Astronomical Observatory (BAO), Ibara, Okayama, Japan,
obtained a low-resolution spectrum (range 400-800 nm, resolution 0.6 nm at
H_alpha) of PSN J11055522+7231203 = SN 2013C with the BAO 1.01-m telescope on
Jan. 5.6 UT.  The spectrum is that of a type-Ia supernova around maximum.  The
absorption minimum of Si II 635.5-nm feature is blueshifted by about 12700
km/s, assuming the resession velocity of PGC 33561 to be 7182 km/s (Emilio et
al. 1999, PASP 111, 438).

     K. Takaki, R. Itoh, I. Ueno, Y. Moritani, H. Akitaya, and K. S. Kawabata,
Hiroshima University; and M. Yamanaka, Kyoto University, obtained a
low-resolution optical spectrogram (range 480-900 nm) of PSN J11055522+7231203
= SN 2013C on Jan. 5.5 UT with the 1.5-m Kanata telescope (+ HOWPol) at the
Higashi-Hiroshima Observatory.  The spectrum exhibits prominent absorption
lines at 495, 565, 623, and 833 nm; they are identified as an Fe II multiplet,
S II 545.4- and 564.0-nm, Si II 635.5-nm, and the Ca II infrared triplet,
respectively.  A comparison with a library of supernova spectra using GELATO
(Harutyunyan et al. 2008, A.Ap. 488, 383) suggests that the spectrum is
consistent with that of the type-Ia supernova 2002bo at four days before its
B-band maximum.

     G. H. Marion and P. Challis, Harvard-Smithsonian Center for Astrophysics
(CfA), on behalf of the CfA Supernova Group, report that a spectrogram (range
340-740 nm) of PSN J11055522+7231203 = SN 2013C was obtained on Jan. 5 UT by
P. Berlind with the F. L. Whipple Observatory 1.5-m telescope (+ FAST).
Cross-correlation with a library of supernova spectra using the "Supernova
Identification" code (SNID; Blondin and Tonry 2007, Ap.J. 666, 1024) shows
that 2013C is a type-Ia supernova about one week before maximum light.  A good
fit is found to the template of the normal type-Ia supernova 2002er at seven
days before maximum.  The velocity of the Si II 635.5-nm absorption feature is
measured to be approximately 12900 km/s, using a redshift of z = 0.023957 for
PGC 33561 (Falco et al. 1999, PASP 111, 438; via NED).


NOTE: These 'Central Bureau Electronic Telegrams' are sometimes
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                         (C) Copyright 2013 CBAT
2013 January 7                   (CBET 3375)              Daniel W. E. Green