2010CBET.2200....3C

A spectrum, obtained on Mar. 11.24 with the 9.2-m Hobby-Eberly Telescope (+ Marcario Low-Resolution Spectrograph) by J. Caldwell, shows 2010ai to be a normal type-Ia supernova a few days before maximum. According to SNID (Blondin and Tonry 2007, Ap.J. 666, 1024), the spectrum of 2010ai best resembles that of SN 1994D at two days before maximum brightness. The best estimation of redshift from SNID is z = 0.014, which is consistent with the redshift of the nearest galaxy (z = 0.018) in the Coma cluster. The photometric measurements are also consistent with a normal type-Ia supernova a few days before maximum at this redshift. The rest-frame photospheric velocity, estimated from the minimum of the Si II 635.5-nm feature, is about 13500 km/s.