Supernova 2011bg = Psn J11561431+2521119

Report the Catalina Real-time Transient Survey's discovery of an apparent supernova in public images from the Catalina Sky Survey (CSS). SN 2011 UT R.A. (2000.0) Decl. Mag. Offset 2011bg Mar. 26.34 11 56 14.31 +25 21 11.9 16.7 1" N This variable was designated PSN J11561431+2521119 when posted at the Central Bureau's TOCP webpage and is here designated SN 2011bg based on the spectroscopic report below. Further unfiltered CCD magnitudes for 2011bg: Mar. 5.33 UT, [18.4 (CSS); 28.31, 16.3 (remotely using a 0.5-m LB-1 telescope at Rodeo, NM, U.S.A.). G. H. Marion, Harvard-Smithsonian Center for Astrophysics (CfA), on behalf of the CfA Supernova Group, reports that a spectrum (range 340-740 nm) of PSN J11561431+2521119 = SN 2011bg was obtained on Apr. 2 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 2011bg is a type-Ia supernova of the 1991T-like sub-class at a few days before maximum light. Using a redshift of z = 0.0322, measured from host-galaxy emission lines, the velocity of the Si II 635.5-nm feature is estimated to be approximately 10500 km/s....