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@eps.harvard.edu (alternate cbat@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