Electronic Telegram No. 2457 Central Bureau for Astronomical Telegrams INTERNATIONAL ASTRONOMICAL UNION CBAT Director: Daniel W. E. Green; Hoffman Lab 209; Harvard University; 20 Oxford St.; Cambridge, MA 02138; U.S.A. e-mail: cbatiau@eps.harvard.edu (alternate cbat@iau.org) URL http://www.cbat.eps.harvard.edu/index.html Prepared using the Tamkin Foundation Computer Network SUPERNOVA 2010hc IN ESO 339-6 N. Morrell, Las Campanas Observatory, Carnegie Supernova Project; and I. Botti and P. Lopez, Universidad de Chile, write that they obtained a spectrogram (range 360-920 nm) of 2010hc (cf. CBET 2429) on Sept. 14.0 UT with the Las Campanas 2.5-m du Pont telescope (+ WFCCD), which shows that 2010hc is an evolved type-Ib supernova. Cross-correlation with a library of supernova spectra using the Supernova Identification tool (SNID; Blondin and Tonry, 2007, Ap.J. 666, 1024) suggests for 2010hc a IIb subtype and an age of roughly two months past explosion, with a best match to SN 1993J at 62 days after explosion. From prominent H-alpha emission of an underlying H II region present in the supernova spectrum, a heliocentric redshift of 6064 km/s is computed, in excellent agreement with that derived by SNID. NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2010 CBAT 2010 September 16 (CBET 2457) Daniel W. E. Green