2009CBET.1857....1M

D. Milisavljevic, R. Fesen, and J. Parrent, Dartmouth College, report that a low-dispersion spectrum (range 420-790 nm) of 2009gi (cf. CBET 1853), taken on June 21.4 UT with the 2.4-m Hiltner telescope (+ CCDS) at MDM Observatory, favors a type-II supernova classification, contrary to what was stated on CBET 1855. Adopting a redshift of z = 0.013, using emission lines of H-alpha, [N II] 658.3-nm, and [S II] at 671.6 and 673.1 nm that are observed in the host galaxy, a broad absorption feature displaying a minimum around 619 nm in interpreted as H-alpha with a blueshifted velocity of 17000 km/s, with absorptions at 563, 640, and 677 nm interpreted as due to He I lines at 587.6, 667.8, and 706.5 nm but blueshifted by 12500 km/s. The "GELATO" spectrum-comparison code (Harutyunyan et al. 2008, A.Ap. 488, 383) provides a good fit to the type-IIb supernova 1987K at seven days past maximum light. Spectral fits with type-Ia templates using the SuperNova Identification code (SNID; Blondin and Tonry 2007, Ap.J. 666, 1024) produce inconsistent redshifts and do not account for the lack of Si II 597.2-nm line absorption typically seen near maximum brightness for type-Ia supernovae. SNID does, however, provide a good fit and consistent redshift for the spectrum with the type-IIb supernova 2000H at ten days past maximum.

Also, a low-dispersion spectrum, taken as above on June 20.4, shows 2009gh (cf. CBETs 1850, 1854) to be a type-II supernova around maximum light. Comparison with a library of supernova spectra using SNID provides a good match with the type-IIP supernova 2004et at 6-8 days past maximum. A strong emission feature identified as H-alpha dominates over the corresponding absorption component.