2008CBET.1409....2B

Additional magnitudes for 2008di: May 8.33, [20.0 (CSS); June 11.19, 17.7 (CSS); 16.25, 18.5 (Palomar 1.52-m reflector + Gunn r filter; non- photometric conditions). The host galaxy of 2008di (SDSS J121642.18+410223.7) has SDSS magnitudes g = 17.9, r = 17.6, and i = 17.4, and spectroscopic redshift z = 0.039. S. Blondin, Harvard-Smithsonian Center for Astrophysics (CfA), on behalf of the CfA Supernova Group, reports that a spectrum (range 350-740 nm) of 2008dh, obtained on June 12.47 UT by M. Calkins with the F. L. Whipple Observatory 1.5-m telescope (+ FAST), shows it to be a type-Ia supernova around maximum light. Cross-correlation with a library of supernova spectra using the "Supernova Identification" code (SNID; Blondin and Tonry 2007, Ap.J. 666, 1024) indicates that 2008dh is most similar to the type-Ia supernova 2000dn at one week past maximum light, at a redshift cz = 11400 ± 600 km/s, consistent with that determined from narrow lines in the host- galaxy spectrum (cz = 11032 ± 237 km/s from four emission lines). Adopting this latter recession velocity for the supernova, the maximum absorption in the Si II line (rest 635.5 nm) is found to be blueshifted by roughly 10800 km/s.