Electronic Telegram No. 2772 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 2011ef IN UGC 12640 = PSN J23305702+1529243 [Editor's Note: This replaces the text on CBET 2770 (designation).] Further to CBET 2753, P. Blanchard, S. B. Cenko, W. Li, and A. V. Filippenko report the LOSS discovery of an apparent supernova on unfiltered KAIT images: SN 2011 UT R.A. (2000.0) Decl. Mag. Offset 2011ef July 18.46 23 30 57.02 +15 29 24.3 17.7 2".7 E, 1".3 S This variable was designated PSN J23305702+1529243 when posted on the Central Bureau's TOCP webpage and is here designated SN 2011ef based on the spectroscopic report below. Additional magnitudes for 2011ef: July 16.44 UT, [18.7 (KAIT); 19.44, 16.2 (KAIT); 20.435, 15.6 (Joseph Brimacombe, Cairns, Australia; five 600-s images with red filter; position end figures 56s.99, 23".7; image posted at http://www.flickr.com/photos/43846774@N02/5959056859/). J. Parrent, D. A. Howell, P. E. Nugent, R. C. Thomas, and M. Sullivan confirm the discovery of PSN J23305702+1529243 in UGC 12640 = SN 2011ef. A CCD spectrum (range 350-900 nm) was taken with the Gemini North telescope on July 20 UT. The spectrum reveals Balmer series and He I P-Cyg profiles superimposed on a relatively blue continuum, indicative of a type-IIb supernova. Assuming a host-galaxy redshift of z = 0.014, the H-alpha absorption feature is blueshifted by about 15800 km/s. A comparison to other spectra of SN 2011dh (http://www.astronomerstelegram.org/?read=3398; CBET 2736) suggests that 2011ef is at a relatively early epoch with respect to 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 NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars.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 July 23 (CBET 2772) Daniel W. E. Green