2010CBET.2208....2C

S. B. Cenko, B. E. Cobb, I. K. Kleiser, and A. V. Filippenko, University of California, Berkeley, report that inspection of a CCD spectrum (range 350-1000 nm), obtained on Mar. 15 UT with the 3-m Shane reflector (+ Kast) at Lick Observatory, shows that 2010am is a type-IIb supernova. Cross-correlation with a library of supernova spectra using the "SuperNova IDentification" code of Blondin and Tonry (2007, Ap.J. 666, 1024) indicates that the spectrum is most similar to that of SN 1997dd near maximum brightness. Narrow emission lines from the host galaxy or an underlying H II region are found at a redshift of 0.020.