Electronic Telegram No. 258 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 2005gn AND 2005hb The "Nearby Supernova Factory" group (N. Blanc, S. Bongard, Y. Copin, E. Gangler, L. Sauge, and G. Smadja, Institut de Physique Nucleaire de Lyon; P. Antilogus, S. Gilles, R. Pain, and R. Pereira, Laboratoire de Physique Nucleaire et de Haute Energies de Paris; G. Aldering, S. Bailey, D. Kocevski, B. C. Lee, S. Loken, P. Nugent, S. Perlmutter, R. Scalzo, R. C. Thomas, L. Wang, and B. A. Weaver, Lawrence Berkeley National Laboratory, Berkeley; C. Bonnaud and E. Pecontal, Centre de Recherche Astronomique de Lyon; R. Kessler, Kavli Institute for Cosmological Physics, Chicago; and C. Baltay, D. Rabinowitz, and A. Bauer, Yale University) reports that spectra (range 320-1000 nm) of SNe 2005gn and 2005hb (cf. IAUC 8616), obtained on Oct. 18.6 UT with the University of Hawaii 2.2-m telescope (+ Supernova Integral Field Spectrograph), indicate that both are type-II supernovae. SN 2005gn is a type-IIn object at a redshift of z = 0.0397, with prominent H-alpha (FWHM 4000 km/s) and Ca II infrared triplet emission. The redshift derived from the peak of the H-alpha feature is a match to that measured for the host, ESO 488-G30 (Andreuzzi et al. 1998, A.Ap. 337, 17). SN 2005hb has spectroscopic features similar to those of the type-IIP supernova 1992H at 36 days after explosion (as reported by Clochiatti et al. 1996, A.J. 111, 1286). NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2005 CBAT 2005 October 19 (CBET 258) Daniel W. E. Green