Electronic Telegram No. 3500 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 2013bw IN UGC 5886 = PSN J10505237-0123269 S. Howerton, Arkansas City, KS, U.S.A.; A. J. Drake, S. G. Djorgovski, A. Mahabal, M. J. Graham, and R. Williams, California Institute of Technology; J. L. Prieto, Princeton University; M. Catelan, Pontificia Universidad Catolica de Chile; and E. Christensen and S. M. Larson, Lunar and Planetary Laboratory, University, report the Catalina Real-time Transient Survey discovery of an apparent supernova in public images from the Catalina Sky Survey (CSS): SN 2013 UT R.A. (2000.0) Decl. Mag. Offset 2013bw Apr. 14.24 10 46 52.37 -01 23 26.9 18.4 13".3 E, 2".1 N Note that the right ascension has been corrected; the variable was designated PSN J10505237-0123269 (based on an erroneous R.A. that was 4 min to the east) when it was posted at the Central Bureau's TOCP webpage and is here designated SN 2013bw based on the spectroscopic confirmation reported below. Additional CCD magnitudes for 2013bw: Mar. 2.26 [20.3 (CSS); 14.26, 19.6 (CSS); Apr. 3.21, 17.9 (CSS); 15.343, 17.2 (Joseph Brimacombe, Cairns, Australia; remotely with a 51-cm RCOS telescope + luminance filter located at the New Mexico Skies observatory near Mayhill, NM, U.S.A.; position end figures 52s.35, 28".2 (he also noted the 50-min discrepancy in R.A.); image posted at website URL http://www.flickr.com/photos/43846774@N02/8653981218/); 16.222, 17.0 (Brimacombe; position end figures 52s.35, 28".6; image posted at website URL http://www.flickr.com/photos/43846774@N02/8657091328/); 18.52, 18.6 (Federica Luppi and Luca Buzzi, Varese, Italy; 0.38-m f/6.8 reflector position end figures 52s.26, 27".4; reference stars from CMC-14 catalogue; a knot, or H II region is visible at the position of 2013bw in Digitized Sky Survey images; image posted at URL http://www.astrogeo.va.it/pub/TOCP/PSN_U5886.jpg). N. Morrell and E. Hsiao, Las Campanas Observatory, on behalf of the Carnegie Supernova Project, report optical spectroscopy (range 370-960 nm) of PSN J10505237-0123269 = SN 2013bw, obtained on Apr. 16 UT with the Las Campanas 2.5-m du Pont telescope (+ WFCCD). Inspection of the data reveals that 2013bw is a young type-II supernova. Cross-correlation with a library of supernova spectra via the Supernova Identification tool (SNID, Blondin and Tonry 2007, Ap.J., 666, 1024) yields best matches with SN 1999em at +9 days for 2013bw. Strong nebular emission from surrounding H II regions is present in the supernova spectra, allowing determination of redshift 0.03889 +/- 0.00009 for 2013bw, in very good agreement with the redshift of 0.0383 quoted in NED for the host galaxy, UGC 5886 (after Jones et al. 2009, The 6dF Galaxy Survey Data Release 3). The authors also note the incorrect R.A. given on the TOCP (and corrected above). NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2013 CBAT 2013 April 26 (CBET 3500) Daniel W. E. Green