2011CBET.2964....2M

Nidia Morrell, Las Campanas Observatory; and Paulina Lira, Universidad de Chile, report that an optical spectrogram (range 363-920 nm) of PSN J00083457-3351148 = SN 2011jo, obtained with the Las Campanas 2.5-m du Pont telescope (+ WFCCD) on Dec. 28.04 UT, shows it to be a type-II supernova shortly after explosion. Cross-correlation with a library of supernova spectra using the supernova identification tool SNID (Blondin and Tonry, 2007, Ap.J. 666, 1024) yields a best match to the spectrum of the type-II-P supernova 1999em at three days before maximum brightness. Considering for the host galaxy an expansion velocity of 6811 km/s (Mathewson et al. 1992, Ap.J. Suppl. 81, 413) – in coincidence with nebular emission from an underlying H II region present on the spectrum – the minimum of the H_beta absorption appears blueshifted by approximately 10800 km/s. Na I absorption at the redshift of the host galaxy is observed with an equivalent width of 0.19 nm.