Electronic Telegram No. 2847 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 2011gm IN NGC 644 = PSN J01385459-4235088 Colin Drescher, Calamvale, Queensland, Australia, reports the discovery by Stuart Parker (Oxford, Canterbury, New Zealand) of an apparent supernova (red mag 15.8, as measured by Drescher) on 30-s unfiltered CCD images taken on Sept. 21.543 and 21.544 UT with a 35-cm f/6.3 Celestron C14 Schmidt-Cassegrain reflector (+ ST10 camera). The new object is located at R.A. = 1h38m54s.59, Decl. = -42d35'08".8 (equinox 2000.0), which is 18" east and 2" south of the nucleus of the galaxy NGC 644 (as measured by Drescher). The variable was designated PSN J01385459-4235088 when it was posted on the Central Bureau's TOCP webpage and is here designated SN 2011gm based on the spectroscopic confirmation reported below. Additional CCD magnitudes for 2011gm, unfiltered unless noted otherwise: Aug. 22.655, [19.4 (Parker); Sept. 23.384, 15.8 (Parker; position end figures 54s.57, 08".9; measured by Drescher); 23.614, R = 15.8 (Joseph Brimacombe, Cairns, Australia; position end figures 54s.56, 08".8); 23.760, 15.6 (Brimacombe; infrared filter, > 700 nm; position end figures 54s.58, 08".1); 24.613, 15.6 (Brimacombe; infrared filter); 25.586, 15.7 (C. Jacques and E. Pimentel, Belo Horizonte, Brazil; imaged with a GRAS telescope at Officer, Australia; limiting magnitude 18.0; position end figures 54s.59, 08".7, UCAC2 reference stars). Brimacombe's image from Sept. 23.6 is posted at website URL http://www.flickr.com/photos/43846774@N02/6176674798/. Brimacombe's image from Sept. 24 is posted at the following website URL: http://www.flickr.com/photos/43846774@N02/6194733505/. D. Milisavljevic, Harvard-Smithsonian Center for Astrophysics; R. Fesen, Dartmouth College; and T. Pickering and A. Gulbis, South African Astronomical Observatory, report that low-dispersion spectra (range 320-900 nm) obtained on Sept. 25.9 UT with the 10-m SALT telescope (+ RSS), show PSN J01385459-4235088 = SN 2011gm to be a type-Ia supernova. Cross-correlation with a library of supernova spectra using the "Supernova Identification" code (SNID; Blondin and Tonry 2007, Ap.J. 666, 1024) shows a good match to the normal type-Ia supernova 1994D at two days after maximum light. After correcting for the recession velocity 6231 km/s (Mathewson et al. 1992, Ap.J. Suppl. 81, 413) of its host galaxy (NGC 644), the velocity of the Si II 635.5-nm feature is estimated to be approximately 10600 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 October 1 (CBET 2847) Daniel W. E. Green