Electronic Telegram No. 345 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 SUPERNOVAE 2005mb, 2005me, 2005ms D. C. Leonard, California Institute of Technology, reports that CCD spectra (range 350-900 nm) of SNe 2005mb and 2005me (cf. IAUC 8647), obtained on Dec. 31 UT with the Keck I 10-m telescope (+ LRISp), show them to be type-II supernovae. The spectral features of SN 2005mb are similar to those of SN 1999em (Leonard et al. 2002, PASP, 114, 35) about 4 weeks after explosion; those of SN 2005me resemble the spectral features of SN 1999em about 2-3 weeks after explosion, with the exception that the H-alpha profile is significantly more emission-dominated in SN 2005me. Adopting the NED recession velocity of 7150 km/s for the host galaxy of SN 2005mb (from Fisher et al. 1995, Ap.J. Suppl. 100, 69), the expansion velocity derived from the minimum of the H_beta line is 5000 km/s. Adopting the NED recession velocity of 6726 km/s for the host galaxy of SN 2005me (from Mathewson et al. 1992, Ap.J. Suppl. 81, 413), the expansion velocity derived from H_beta is 7200 km/s. Leonard adds that similarly obtained CCD spectra of SN 2005ms (cf. IAUC 8651) show it to be of type Ia, with a spectral-feature age (Riess et al. 1997, A.J. 114, 722) of about 3 days past maximum brightness. Adopting the NED recession velocity of 7556 km/s for the host galaxy (from de Vaucouleurs et al. 1991, Third Reference Catalogue of Bright Calaxies, Version 3.9), the expansion velocity derived from the minimum of the Si II 635.5-nm line is 13300 km/s, which is somewhat higher than is typical for this evolutionary stage. Preliminary reduction of the red-side spectropolarimetry (range 560-900 nm) indicates a low overall observed polarization level (< 0.4 percent) but with a significant modulation of about 0.5 percent detected across the Si II 635.5-nm absorption trough. NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2005 CBAT 2005 December 31 (CBET 345) Daniel W. E. Green