[IAUC] CBET 3079: 20120330 : SUPERNOVA 2012bo IN NGC 4726 = PSN J12504523-1416085

Vie Mar 30 09:39:37 ART 2012

                                                  Electronic Telegram No. 3079
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 2012bo IN NGC 4726 = PSN J12504523-1416085
     Koichi Itagaki, Yamagata, Japan reports his discovery of an apparent
supernova (mag 16.4) on an unfiltered CCD image (limiting magnitude 19.5)
taken on Mar. 27.709 UT with a 0.60-m f/5.7 reflector.  The new object is
located at R.A. = 12h50m45s.23, Decl. = -14d16'08".5 (equinox 2000.0; UCAC3
reference stars), which is 12".4 west and 1".5 south of the nucleus of the
presumed host galaxy, NGC 4726.  Itagaki posted his discovery image at website
URL http://www.k-itagaki.jp/images/psn4726.jpg.  The variable was designated
PSN J12504523-1416085 when it was posted at the Central Bureau's TOCP webpage
and is here designated SN 2012bo based on the spectroscopic confirmation
reported below.  Additional magnitudes for 2012bo (unfiltered CCD unless noted
otherwise):  1992 May 24, [19.3 (Digitized Sky Survey, red plate; via T. Yusa,
Osaki, Japan); 2005 May 5.62, [19.0 (Itagaki); Mar. 28.280, 17.4 (Yusa;
remotely using a 0.25-m f/3.4 hyperbolic astrograph + SBIG ST-8XE camera at
the New Mexico Skies Observatory near Mayhill, NM, U.S.A.; position end
figures 45s.20, 08".1; offset 12".6 west, 1".0 south; UCAC-3 reference stars;
limiting magnitude 19.5; image posted at the following website URL:
http://space.geocities.jp/yusastar77/supernova/PSNinNGC4726_120328.htm);
28.285, 16.1 (Joseph Brimacombe, Cairns, Australia; remotely using a 51-cm
RCOS telescope + STL11K camera + luminance filter at the New Mexico Skies
Observatory; position end figures 45s.21, 07".9; image posted at website URL
http://www.flickr.com/photos/43846774@N02/7025638787/); 28.515, 16.5 (T.
Noguchi, Katori, Chiba-ken, Japan, 0.23-m f/6.3 reflector + BITRAN BT-11E
camera; limiting mag 18.0; position end figures 45s.14, 08".6; communicated
by Syuichi Nakano, Sumoto, Japan).

     E. Cappellaro, A. Pastorello, L. Tomasella, S. Benetti, M. Fiaschi, P.
Ochner, M. Turatto, and S. Valenti, Osservatorio Astronomico di Padova,
Istituto Nazionale di Astrofisica, report that a spectrogram of PSN
J12504523-1416085 = SN 2012bo, obtained on Mar. 28.97 UT with the Asiago
1.82-m Copernico Telescope (+ AFOSC; range 340-820 nm; resolution 2.4 nm),
suggests that it is a type-Ia supernova.  Adopting for the host galaxy (NGC
4726) a redshift z = 0.0254 (Jones et al. 2009, "6DF Galaxy Survey Data
Release 3"; via the NED database), a comparison with a library of supernovae
spectra via GELATO (Harutyuyan et al. 2008, A.Ap. 488, 383) indicates that
2012bo is similar to SN 2003du (Stanishev et al. 2007, A.Ap. 469, 645) around
one week before B-band maximum light.  The expansion velocity deduced from the
Si II 635.5-nm minimum is about 10700 km/s.

     M. R. Drout, D. Milisavljevic, A. Soderberg, and E. Berger, Harvard
University, report on low-dispersion spectra (range 330-850 nm), taken on Mar.
29.4 UT with the 6.5-m MMT (+ Blue Channel), show PSN J12504523-1416085 = SN
2012bo to be a type-Ia supernova near maximum light.  Comparison with a
library of supernova spectra using the "Supernova Identification" tool (SNID;
Blondin and Tonry 2007, Ap.J., 666, 1024) provides a good match with the
normal type-Ia supernova 2003du at six days before maximum.  Using the host-
galaxy (NGC 4726) redshift of z = 0.025 (Jones et al. 2009, MNRAS 399, 683)
the velocity of the Si II 635.5-nm feature is estimated to be approximately
-11000 km/s.


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

                         (C) Copyright 2012 CBAT
2012 March 30                    (CBET 3079)              Daniel W. E. Green