Electronic Telegram No. 500 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 2006bx IN UGC 5434 Further to IAUC 8693, D. R. Madison and W. Li report the LOSS discovery of an apparent supernova (mag 18.1) on unfiltered KAIT images taken on May 1.26 and 2.22 UT. The new object is located at R.A. = 10h05m14s.16, Decl. = +21o28'32".0 (equinox 2000.0), which is 8".5 east and 70".8 north of the center of UGC 5434. A KAIT image taken on Feb. 23.38 showed nothing at this position (limiting mag about 19.5). S. Blondin, M. Modjaz, R. Kirshner, and P. Challis, Harvard-Smithsonian Center for Astrophysics, report that a spectrogram (range 350-740 nm) of SN 2006bx, obtained by T. Groner on May 3.18 UT with the F. L. Whipple Observatory 1.5-m telescope (+ FAST), shows it to be a slightly reddened type-II supernova roughly 2-3 weeks past explosion. The spectrum is dominated by P-Cyg lines of hydrogen, sodium, and iron, consistent with the plateau phase of a normal type-II supernova. The spectrum is similar to the type-II-plateau supernova 1999em at 21 days past explosion (Leonard et al. 2001, Ap.J. 553, 861). Adopting a recession velocity of 5580 km/s for the host galaxy (from http://tdc-www.harvard.edu/uzc/), the maximum absorption in the H_beta line (rest 486.1 nm) is blueshifted by 6000 km/s. NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2006 CBAT 2006 May 3 (CBET 500) Daniel W. E. Green