Electronic Telegram No. 2746 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 2011dn IN UGC 11501 = PSN J19583553+0236163 Simone Leonini, Siena, Italy, reports the discovery of an apparent supernova (mag about 16.8) on an unfiltered CCD image (limiting mag about 19.2) taken on June 21.931 UT during the Montarrenti Observatory Supernovae Search program (part of the Italian Supernovae Project) using a 0.53-m f/7.8 Ritchey-Chretien telescope (+ Apogee Alta U47 CCD camera). The new object is located at R.A. = 19h58m35s.53, Decl. = +2d36'16".3 (equinox 2000.0), which is 26" west of the nucleus of the galaxy UGC 11501. No stellar source is visible at this position in their past images from 2009 June 16 to 2011 May 30 (limiting mag about 19.0) or on Palomar Sky Survey infrared, red, and blue plates (1995 August 16, F plate; 1992 July 1, J plate; 1990 June 20, N plate, limiting mag 20.0). Confirmation images were obtained on 2011 June 22.93 by L. M. Tinjaca Ramirez using the discovery telescope, with the variable then at (mag about 17.1; limiting mag about 19.2). The new object was designated PSN J19583553+0236163 when posted at the Central Bureau's TOCP webpage and is here designated SN 2011dn based on the spectroscopic report below. The discovery image is posted at the following website URL: http://www.jacopobaldi.it/dati/PSN%20in%20UGC11501.jpg, and the confirmation at http://www.jacopobaldi.it/dati/confirmation%20PSN%20in%20UGC11501.jpg. Additional unfiltered CCD magnitudes for SN 2011dn: June 23.23-23.30 UT, 16.5 (R. A. Koff, Bennett, CO, U.S.A.; Celestron 0.20-m f/10 reflector + SBIG ST-6 CCD camera; multiple co-added images); 23.354, 16.1 (Joseph Brimacombe, Cairns, Australia; three co-added 60-s images; position end figures 35s.56, 11".3). Brimacombe's image is posted at the following website URL: http://www.flickr.com/photos/43846774@N02/5865118910/. D. C. Leonard, San Diego State University; J. Moustakas, University of California at San Diego; B. J. Swift and D. McCarthy, University of Arizona; V. Bailey, E. Carrico, A. Carter, E. Chui, E. Douglas, E. Eggeman, R. Goldberg, R. Grant, K. Hartman, J. Hellerstein, E. Hooper, C. Horlick-Cruz, L. Hunter, T. Jiles, E. D. Johnson, K. Kumar, L. Lappe, J. Lee, W. Lee, F. Marsh, G. Mehta, P. Miller, R. Rampalli, J. Reed, K. Rice, H. Saldivar, M. Salgado-Flores, A. Schlingman, W. F. Schlingman, W. M. Schlingman, S. Scibelli, K. Sinclair, I. Steincamp, N. Stock, N. Todd, L. L. Aizpuru Vargas, S. Yamanaka, and E. Zachary, 2011 Advanced Teen Astronomy Camp, report that inspection of a low-dispersion optical spectrum (range 370-690 nm) of PSN J19583553+0236163 = SN 2011dn, obtained with the 2.3-m Bok telescope (+ Boller & Chivens spectrograph) at Steward Observatory on June 23 UT, shows it to be a type-Ia supernova of the SN-1991T-like sub-class, several days before maximum light. Cross-correlation with a library of supernova spectra using the "Supernova Identification" code (SNID; Blondin and Tonry 2007, Ap.J. 666, 1024) finds good matches with pre-maximum (-6.4 +/- 2.7 days) template spectra of SN 1991T, SN 1997br, and SN 1999aa. Adopting the NASA/IPAC Extragalactic Database (NED) recession velocity for UGC 11501 of 7572 km/s (a 21-cm H I line measurement taken from Springob et al. 2005, Ap.J. Suppl. 160, 149), the maximum absorption in the (weak) Si II line (rest 635.5 nm) is blueshifted by approximately 10100 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 June 24 (CBET 2746) Daniel W. E. Green