Electronic Telegram No. 2792 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 2011fe IN M101 = PSN J14030581+5416254 Peter E. Nugent, Lawrence Berkeley National Laboratory (LBL) and University of California at Berkeley; Mark Sullivan, Oxford University; David Bersier, Liverpool John Moores University; D. A. Howell, Las Cumbres Observatory Global Telescope and University of California at Santa Barbara; Rollin Thomas, LBL; and Phil James, Liverpool John Moores University, report report the discovery of a type-Ia supernova (magnitude g = 17.2) by the "Type Ia supernova science working group of the Palomar Transient Factory" on g-band images obtained with the Oschin 1.2-m Schmidt telescope at Palomar on Aug. 24 UT. The supernova is located at R.A. = 14h03m05s.81, Decl. = +54d16'25".4 (equinox 2000.0), which (according to D. Bishop, Rochester, NY, USA) is 59" west and 271" south of the center of M101; nothing was visible at this position on an image from Aug. 23 (limiting mag 20.6). The variable was designated PSN J14030581+5416254 when posted on Aug. 24.99 on the Central Bureau's TOCP webpage by Bishop and is here designated SN 2011fe based on the spectroscopic report below by Nugent et al. A preliminary spectrum obtained on Aug. 24 UT with FRODOSPEC on the Liverpool Telescope indicates that 2011fe is probably a very young type-Ia supernova; broad absorption lines (particularly the Ca II infrared triplet) are visible. The presence of an H-alpha feature is confidently rejected. Additional magnitudes for SN 2011fe, reported in part by E. Waagen, AAVSO (unfiltered CCD unless otherwise noted): Aug. 24.910 UT, 12 (Mathew A. Marulla and Tavi A. Grenier, 0.5-m f/6.8 corrected Dall-Kirkham telescope + FLI PL09000 CCD camera, SLOOH Canary Islands Observatory, Mt. Teide; independent discovery; position end figures 33s.2, 13'16"; offset 3'26" from the center of M101 in p.a. 191.4 deg; discovery image posted at website URL http://admin.slooh.com/files/m101_position.png); Aug. 25.093, V = 14.89 +/- 0.07 (J. Roe, Wentzville, MO, U.S.A.); Aug. 25.130, V = 14.79 +/- 0.02 (S. Howerton, Arkansas City, KS, U.S.A.); Aug. 25.16, 14.8 (R. A. Koff, Bennett, CO, U.S.A.; Meade 0.25-m f/10 reflector + Apogee AP-47p CCD camera; position end figures 05s.75, 16'25".2; nothing visible at this position on the Digitized Sky Survey to limiting mag 18.5, bandpass not noted); Aug. 25.200, 14.7 (R. Royer, Springville, CA, U.S.A.; visual); Aug. 25.200, 14.9 (Joseph Brimacombe, Cairns, Australia; position end figures 05".74, 16'25".3; image posted at website URL http://www.flickr.com/photos/43846774@N02/6079812340/); Aug. 25.83, R = 13.9 +/- 0.3, V = 13.8 +/- 0.3, B = 13.8 +/- 0.3 (K. Sarneczky, 0.60-m Schmidt telescope, Konkoly Observatory, Hungary); Aug. 25.853, 13.4 (Gianluca Masi, using 0.43-m f/6.8 telescope of the Virtual Telescope robotic facility in Ceccano, Italy; position end figures 05s.74, 16'25".7, using 295 reference stars from the NOMAD catalogue). Masi's image is posted at URL http://virtualtelescope.bellatrixobservatory.org/m101sn.html. Koff's image is posted at the following website URL: http://antelopehillsobservatory.org/SNpictures/PSNJ14030581+5416254final.jpg. NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2011 CBAT 2011 August 26 (CBET 2792) Daniel W. E. Green