Electronic Telegram No. 674 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 2006jc IN UGC 4904 Further to CBET 672, R. Fesen, D. Milisavljevic, and G. Rudie, Dartmouth College, report that a re-examination of a fully reduced 400- to 700-nm spectrum of SN 2006jc, taken with the MDM 2.4-m telescope on Oct. 12.5 UT, although exhibiting somewhat stronger absorption at 570 nm and an unusually strong continuum shortward of 450 nm, shows an otherwise type-Ia-supernova-like spectrum some 15-20 days after maximum -- similiar to that seen in SN 1994D (cf. Fillippenko 1997, ARAA 35, 309). Although features near 600 nm appear similar to those exhibited by type-IIb/Ib supernovae at late times (e.g., SN 1996cb; cf. Matheson et al. 2001, Ap.J. 121, 1648), the spectrum exhibits the 610-nm Si II absorption feature characteristic of type-Ia supernovae at early times. S. Benetti, E. Cappellaro, N. Elias-Rosa, and A. Harutyunyan, Istituto Nazionale di Astrofisica, Padua Observatory; R. Chornock, A. V. Filippenko, and R. J. Foley, University of California, Berkeley; A. Pastorello, Queen's University, Belfast; and G. Andreuzzi, Telescopio Nazionale Galileo (TNG, report that inspection of CCD spectra (range 332-1000 nm; resolution 1.3 nm), obtained on Oct. 12.23 UT with the 3.5-m TNG telescope (+ DOLORES), shows that SN 2006jc is a very peculiar supernova, probably related to type Ib, but of a rare variety: "The closest comparison that we have been able to find is with SN 1999cq (Matheson et al. 2000, A.J. 119, 2303) and SN 2002ao (Filippenko and Chornock 2002, IAUC 7825), which were characterized by strong He I emission lines. There are some distinct differences, however, perhaps indicating a different phase of development or considerable heterogeneity within this peculiar subclass." NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2006 CBAT 2006 October 16 (CBET 674) Daniel W. E. Green