Electronic Telegram No. 277 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://cfa-www.harvard.edu/iau/cbat.html SUPERNOVA 2005ir A supernova has been discovered independently by two groups: the Sloan Digital Sky Survey II collaboration (cf. CBET 259 and 268; communicated by J. Frieman, Fermilab and University of Chicago) via multiple g, r, and i images taken with the SDSS 2.5-m telescope, and by R. Quimby, M. Sellers and F. Castro (University of Texas) via the 0.45-m ROTSE-IIIb telescope at the McDonald Observatory (found by subtracting a co-addition of images taken between Aug. 22 and 28; limiting mag about 18.9). Quimby et al. provide the following precise position for SN 2005ir: R.A. = 1h16m43s.76, Decl. = +0o47'40".4 (equinox 2000.0; uncertainty +/- 0".6), which is 1".7 west and 3".4 north of the center of the apparent host galaxy. Frieman et al. provide position end figures 43s.80, 40".6. Available magnitudes (unfiltered unless otherwise noted) for 2005ir: Aug. 28, [18.9 (Quimby et al.); Oct. 28 UT, g = 21.1 (SDSS II); Nov. 3.11, 18.5 (Quimby et al.); 6.14, 17.8 (Quimby et al.). Spectroscopy by the SDSS II group finds the supernova to be of type Ia with a redshift z = 0.08, and they estimate that the peak brightness will occur around Nov. 13. Quimby adds that a spectrogram (range 420-890 nm), obtained on Nov. 6.27 with the 9.2-m Hobby-Eberly Telescope (+ Marcario Low-Resolution Spectrograph) by M. Shetrone and E. Terrazas, shows 2005ir to be a type-Ia supernova near maximum light; adopting the SDSS redshift of the apparent host (z = 0.0764), the expansion velocity derived from the minimum of the Si II (rest 635.5 nm) line is 14000 km/s. NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2005 CBAT 2005 November 7 (CBET 277) Daniel W. E. Green