Electronic Telegram No. 2726 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 2011dc = PSN 14585651+6554083 A. J. Drake, S. G. Djorgovski, A. Mahabal, M. J. Graham, and R. Williams, California Institute of Technology; J. L. Prieto, Carnegie Observatories; M. Catelan, Pontificia Universidad Catolica de Chile; E. C. Beshore and S. M. Larson, Lunar and Planetary Laboratory, University of Arizona; and E. Christensen, Gemini Observatory, report the Catalina Real-time Transient Survey's discovery of an apparent supernova in unfiltered Catalina Sky Survey images: SN 2011 UT R.A. (2000.0) Decl. Mag. Offset 2011dc May 14.32 14 58 56.51 +65 54 08.3 17.0 9".5 W, 2".0 S This variable was designated PSN 14585651+6554083 when posted at the Central Bureau's TOCP webpage and is here designated SN 2011dc based on the spectroscopic report below. Further magnitudes for 2011dc: Apr. 2.37 UT, [19.0 (Catalina Sky Survey); May 15.237, 17.1 (Joseph Brimacombe, Cairns, Australia; from four stacked 1200-s images taken remotely using a 51-cm RCOS telescope + red filter + STL11K camera at New Mexico Skies Observatory near Mayhill, NM, U.S.A.; position end figures 56s.5, 07".8). Brimacombe's image is posted at http://www.flickr.com/photos/43846774@N02/5729478332/. L. Tomasella, P. Ochner, S. Valenti, and S. Benetti, Istituto Nazionale di Astrofisica, Osservatorio Astronomico di Padova; and A. Pastorello, Dipartimento di Astronomia, Universita di Padova, on behalf of a larger collaboration, report that a noisy spectrogram (range 390-810 nm; resolution 2.2 nm) of PSN 14585651+6554083 = SN 2011dc, obtained on May 26.03 UT under poor weather conditions by the Service Telescope Operator Team with the Ekar-Copernicus 1.82-m telescope (+ AFOSC), suggests that 2011dc is likely a type-I supernova; if a broad absorption measured at 644.0 nm is identified with Si II 635.5-nm, the redshift of 2011dc is between 0.04 and 0.05. NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2011 CBAT 2011 May 28 (CBET 2726) Daniel W. E. Green