Electronic Telegram No. 2825 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 2011fs IN UGC 11975 = PSN J22171952+3534500 Zhangwei Jin (Ningbo, Zhejiang, China) and Xing Gao (Urumqi, Xinjiang, China) report the discovery of a possible supernova (mag approximately 16.8) on an unfiltered 60-s survey CCD image (limiting mag about 19.0) taken by Xing Gao on Sept. 15.769 UT in the course of the Xingming Observation Sky Survey at Mt. Nanshan (Celestron C14 0.35-m f/6.9 Schmidt-Cassegrain telescope). The new object is approximately located at R.A. 22h17m19s.52, Decl. = +35d34'50".0 (equinox 2000.0), which is about 2".0 west and 34" north of the center of UGC 11975. Nothing is visible at this position on their archival images taken on Aug. 24 (limiting mag 19.5) or on a Digitized Sky Survey image from 1986 Sept. 26 (limiting red mag about 19.8). The discoverers have posted their image at website URL http://www.xjltp.com/XOSS/XM23ZJ/XM23ZJ.htm. When the object was posted on the Central Bureau's TOCP webpage, it was given the preliminary designation PSN J22171952+3534500; it is here given the designation SN 2011fs based on the spectroscopy reported below. Additional CCD magnitudes (unfiltered unless noted otherwise) for 2011fs: Sept. 16.519, R = 16.5 (J. Brimacombe, Cairns, Australia; position end figures 19s.52, 49".9); 16.555, 17.2 (Brimacombe; infrared filter; position end figures 19s.51, 49".9); 17.388, 16.3 (Brimacombe; position end figures 19s.54, 49".9); 17.438, 16.6 (T. Noguchi, Katori, Chiba-ken, Japan; 0.23-m f/6.3 Schmidt-Cassegrain telescope + BITRAN BT-11E camera; limiting mag 18.0; position end figures 19s.48, 50".0; UCAC3 reference stars; communicated via Syuichi Nakano, Sumoto, Japan); 19.575, 16.1 (Jin and Gao; position end figures 19s.50, 49".6); 20.274, 15.8 (Brimacombe). The Sept. 17 image by Brimacombe is posted at URL http://www.flickr.com/photos/43846774@N02/6157852436/; his Sept. 20.274 image is posted at http://www.flickr.com/photos/43846774@N02/6174570633/. D. D. Balam, Dominion Astrophysical Observatory, National Research Council of Canada (NRCC); M. L. Graham, Las Cumbres Observatory Global Telescope, University of California at Santa Barbara; E. Y. Hsiao, Lawrence Berkeley Laboratory; and D. W. E. Green, Harvard University, report that a spectrogram (range 362-693 nm, resolution 0.3 nm) of PSN J22171952+3534500 = SN 2011fs, obtained on Sept. 24.19 UT with the 1.82-m Plaskett Telescope of the NRCC, shows it to be a type-Ia supernova near maximum light. Cross- correlation with a library of supernova spectra using the "Supernova Identification" code (Blondin and Tonry 2007, Ap.J. 666, 1024) indicates that 2011fs is most similar to the type-Ia supernova 1999aa at 5 days before maximum light. L. Tomasella, S. Valenti, P. Ochner, S. Benetti, and E. Cappellaro, 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 J22171952+3534500 = SN 2011fs was obtained on September 23.95 UT. The spectrum is that of a type-Ia supernova observed about one week before maximum. The velocity of the ejected material, as deduced from the position of the minimum of the Si II lines, is about 11600 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 September 25 (CBET 2825) Daniel W. E. Green