Electronic Telegram No. 1502 Central Bureau for Astronomical Telegrams INTERNATIONAL ASTRONOMICAL UNION M.S. 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A. IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions) CBAT@CFA.HARVARD.EDU (science) URL http://www.cfa.harvard.edu/iau/cbat.html SUPERNOVA 2008fn F. Yuan, University of Michigan; R. Quimby, California Institute of Technology; D. Chamarro, University of Michigan; A. Uecker, Indiana University of Pennsylvania; M. D. Sisson and C. Akerlof, University of Michigan; and J. C. Wheeler, University of Texas, on behalf of the ROTSE collaboration, report the discovery of a supernova (mag about 17.1) on an unfiltered CCD image taken on Aug. 4.17 UT (found by subtracting a reference image built from images taken in Aug. 2007) with the 0.45-m ROTSE-IIIb telescope at McDonald Observatory. The new object is located at R.A. = 16h21m48s.53, Decl. = +37o03'41".0 (equinox 2000.0; uncertainty < 1"), which is 2".1 north of the center of the apparent host galaxy (whose SDSS redshift is z = 0.030). SN 2008fn was observed to rise to mag about 16.8 on Aug. 10.18 and then decay to mag about 17.4 on Aug. 20.14. A finding chart of 2008fn can be found at the following website URL: http://www.rotse.net/rsvp/j162148.53+370341/j162148.53+370341.jpg. The ROTSE magnitudes quoted above are unfiltered, calibrated to R magnitudes from the USNO-B1.0 catalogue. E. Y. Hsiao, M. L. Graham, C. J. Pritchet, and D. Balam, Department of Physics and Astronomy, University of Victoria, report that a noisy spectrogram (range 390-703 nm, resolution 0.3 nm) of 2008fn, obtained on Sept. 10.23 UT with the 1.82-m Plaskett Telescope of the National Research Council of Canada, shows it to be a type-Ibc supernova at 2 weeks past maximum light. According to the 'superfit' matching program of Howell et al. (2005, Ap.J. 634, 1190), the best fit is to the spectrum of SN 2002ap at 12 days past maximum light. The fit is consistent with the redshift of the presumed host galaxy, 2MASX J16214855+3703386 (z = 0.0298, Sloan Digital Sky Survey Data Release 3). One cannot rule out the possibility that the object is a late-time type-Ia supernova. NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2008 CBAT 2008 September 10 (CBET 1502) Daniel W. E. Green