Supernova 2011gf = Psn J21122427-0748521

Report the discovery of an apparent supernova in unfiltered Catalina Sky Survey images: SN 2011 UT R.A. (2000.0) Decl. Mag. Offset 2011gf Sep. 18.19 21 12 24.27 - 7 48 52.1 16.6 23".5 E, 21".8 N This variable was designated PSN J21122427-0748521 when it was posted on the Central Bureau's TOCP webpage and is here designated SN 2011gf based on the spectroscopic report below. Joseph Brimacombe, Cairns, Australia, reports unfiltered CCD mag 16.1 and position end figures 24s.31, 51".8 from an image taken on Sept. 19.266 UT; he has posted his image at the following website URL: http://www.flickr.com/photos/43846774@N02/6167975455/. S. Valenti, S. Benetti, L. Tomasella, and P. Ochner, Osservatorio Astronomico di Padova, Istituto Nazionale di Astrofisica; and A. Pastorello, Dipartimento di Astronomia, Universita di Padova, on behalf of a larger collaboration, report that a spectrogram (range 360-810 nm; resolution 2.2 nm) of PSN J21122427-0748521 = SN 2011gf, obtained on Sept. 25.90 UT, suggestss that it is a type-Ia supernova. Cross-correlation with a library of supernova spectra via the "GELATO" code (Harutyunyan et al. 2008, A.Ap. 488, 383; available at URL https://gelato.tng.iac.es/login.cgi), suggest a normal type-Ia supernova close to the B-band maximum at a redshift of z = 0.0277 (Sloan Digital Sky Survey, via the NED website). The expansion velocity deduced from the Si II 635.5-nm minimum is about 11100 km/s. G. H. Marion, Harvard-Smithsonian Center for Astrophysics (CfA), on behalf of the CfA Supernova Group, report that a spectrum (range 340-740 nm) of PSN J21122427-0748521 = 2011gf was obtained on Sept. 27 UT by Marion with the F. L. Whipple Observatory 1.5-m telescope (+ FAST). Cross-correlation with a library of supernova spectra using the "Supernova Identification" code (SNID; Blondin and Tonry 2007, Ap.J. 666, 1024) shows that 2011gf is a type-Ia supernova a few days after maximum light. The best-fit template spectrum is that of SN 2007F at +4 days. The velocity of the Si II 635.5-nm feature is estimated to be approximately 11600 km/s, using the SNID estimated redshift of z = 0.027....