Supernova 2011gt in IC 4913 = Psn J19564826-3719375

Report the discovery of an apparent supernova in public images from the Siding Spring Survey (SSS). SN 2011 UT R.A. (2000.0) Decl. Mag. Offset 2011gt Sep. 26.42 19 56 48.26 -37 19 37.5 16.0 7".6 E, 4".5 N The new object was designated PSN J19564826-3719375 when it was posted on the Central Bureau's TOCP webpage and is here designated SN 2011gt based on the spectroscopic confirmation reported below. Additional CCD magnitudes for 2011gt (unfiltered unless otherwise noted): Aug. 22.48 UT, [18.5 (SSS); Sept. 27.109, 15.7 (C. Jacques and E. Pimentel, Belo Horizonte, Brazil; position end figures 48s.25, 37".9; UCAC2 reference stars; image posted at URL http://ceamig-rea.net/SUPERNOVAE/CONFIRMATIONS/PSN_J19564826-3719375/I4913.jpg); 27.467, R = 15.6 (P. Miller, P. Roche, A. Tripp, R. Miles, R. Holmes, S. Foglia, and L. Buzzi with the 2.0-m f/10 Faulkes Telescope South + Bessell R filter at Siding Spring; position end figures 48s.28, 38".0; PPMXL catalogue; image posted at URL http://www.astrogeo.va.it/pub/TOCP/PSN_I4913_FTS.jpg); 27.467, R = 17.5 (Joseph Brimacombe, Cairns, Australia; position end figures 48s.27, 37".3; image at http://www.flickr.com/photos/43846774@N02/6190491181/); Oct. 1.560, R = 17.6 (Brimacombe; image posted at the following website URL: http://www.flickr.com/photos/43846774@N02/6203147137/). J. Anderson, Universidad de Chile; and G. Pignata, Universidad Andres Bello, on behalf of the Millennium Center for Supernova Science, report that they obtained a spectrogram of PSN J19564826-3719375 = SN 2011gt on Sept. 30.1 UT with the Magellan II Clay 6.5-m telescope (+ LDSS3) at Las Campanas Observatory, which shows it to be a type-Ia supernova. Comparison with a library of supernova spectra via the "Supernova Identification" tool (Blondin and Tonry 2007, Ap.J. 666, 1024) provides very good matches with normal type-Ia events around 3 weeks past maximum light....