Electronic Telegram No. 2721 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 2011cj IN UGC 9356 = PSN J14325381+1135493 Further to CBET 2712, G. Li, S. B. Cenko, W. Li, and A. V. Filippenko report the LOSS/KAIT discovery of an apparent supernova on unfiltered KAIT images: SN 2011 UT R.A. (2000.0) Decl. Mag. Offset 2011cj May 9.39 14 32 53.81 +11 35 49.3 17.0 4".4 E, 7".5 N Nothing was visible at this position on a KAIT image taken on May 5.39 UT (limiting mag 18.5). This variable was designated PSN J14325381+1135493 when posted on the Central Bureau's TOCP webpage and is here designated SN 2011cj based on the spectroscopic reports below. G. H. Marion, Harvard-Smithsonian Center for Astrophysics and University of Texas; J. Vinko, University of Szeged; and J. C. Wheeler, University of Texas, report that a spectrum (range 430-1000 nm) of PSN J14325381+1135493 = SN 2011cj was obtained by J. Caldwell on May 12 UT with the 9.2-m Hobby-Eberly Telescope (+ Marcario Low-Resolution Spectrograph). Cross-correlation with a library of supernova spectra using the "Supernova Identification" code (SNID; Blondin and Tonry 2007, Ap.J. 666, 1024) shows that 2011cj is a type-IIP supernova near maximum brightness. J. M. Silverman, A. V. Filippenko, and W. Li, University of California, Berkeley, report that inspection of a CCD spectrum (range 340-1000 nm), obtained by K. Hiner (University of California, Riverside) and A. Diamond- Stanic (University of California, San Diego) on May 11 UT with the 3-m Shane reflector (+ Kast) at Lick Observatory, shows that PSN J14325381+1135493 = SN 2011cj is a very young type-II supernova. The broad H-alpha emission component has a substantially blueshifted centroid and greatly dominates over the absorption component, and the continuum is quite blue. There appears to be broad, weak emission in the range 450-470 nm (blending with H-beta emission around 480 nm), probably corresponding to C III/N III and He II, as is commonly seen in Wolf-Rayet stars and in some other very young type-II supernovae (e.g., SN 1998S; Leonard et al. 2000, Ap.J. 536, 239). However, unlike the case of SN 1998S, there is no clear evidence for an intermediate- width or narrow component, so the object is not a type-IIn evemt at this stage. After removal of the host-galaxy recession velocity of 2300 km/s, determined from narrow emission lines, the absorption minimum of the H-alpha line is found to be blueshifted by 16000 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 May 13 (CBET 2721) Daniel W. E. Green