Electronic Telegram No. 2753 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 2011du = PSN J18564206+3638107 Further to CBET 2745, J. Kelly, S. B. Cenko, W. Li, and A. V. Filippenko report the LOSS discovery of an apparent supernova on unfiltered KAIT images. The object was designated PSN J18564206+3638107 when posted at the Central Bureau's TOCP webpage and is here designted SN 2011du based on the spectroscopic confirmation reported below. SN 2011 UT R.A. (2000.0) Decl. Mag. Offset 2011du June 23.40 18 56 42.06 +36 38 10.7 18.8 0".5 E, 2".3 S Additional unfiltered CCD magnitudes for 2011du: a co-added frame from June 2 to 19 UT, [19.8 (KAIT); June 24.39, 19.1 (KAIT); 26.424, 18.3 (J. Brimacombe, Cairns, Australia; position end figures 42s.15, 10".9). Brimacombe's image is posted at website URL http://www.flickr.com/photos/43846774@N02/5875187042/. J. M. Silverman, S. B. Cenko, P. E. Nugent, and A. V. Filippenko, University of California, Berkeley, report that inspection of a CCD spectrum (range 340-1000 nm), obtained on June 29 UT with the 10-m Keck I telescope (+ LRIS), shows that PSN J18564206+3638107 = SN 2011du is a type-II supernova. After removal of the host-galaxy recession velocity of 17600 km/s, determined from narrow emission features, the absorption minimum of the H-alpha line is found to be blueshifted by about 12000 km/s. NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2011 CBAT 2011 June 30 (CBET 2753) Daniel W. E. Green