2010CBET.2311....1C

P. Challis, R. Foley, G. H. Marion, and R. Kirshner, Harvard-Smithsonian Center for Astrophysics (CfA); and J. Ruel, Physics Department, Harvard University, on behalf of the CfA Supernova Group, report on spectroscopic observations that were obtained of 2010do, 2010dt, and 2010dw by P. Berlind on June 7 UT with the F. L. Whipple Observatory 1.5-m telescope (+ FAST; range 360-760 nm) and of 2010do by R. J. Foley and J. Ruel on June 8 with the Magellan telescope (+ IMACS; range 630-950 nm). SN 2010do (cf. CBET 2301) is a type-Ic supernova near maximum light. Cross-correlation with a library of supernova spectra using the "Supernova Identification" code (SNID; Blondin and Tonry 2007, Ap.J. 666, 1024) finds that the spectrum of 2010do is similar to that of SN 1994I at maximum light. However, the presence of weak He I features cannot be ruled out. Using 4382 km/s as the heliocentric velocity for the host galaxy (Paturel et al. 2003, A.Ap. 412, 57), the velocity for Ca II is about 14000 km/s, measured at the absorption minima of features from the H and K lines and the infrared triplet. C II lines at 658.0 and 723.5 nm are measured at about 6000 km/s. SNID indicates that 2010dw (cf. CBET 2310) is a normal type-Ia supernova a few days before maximum light, and 2010dt (cf. CBET 2307) is a normal type-Ia supernova near maximum light.