2008CBET.1427....2B

S. Blondin, Harvard-Smithsonian Center for Astrophysics (CfA), on behalf of the CfA Supernova Group, reports that a spectrum (range 350-740 nm) of 2008dx, obtained on June 27.26 UT by M. Calkins with the F. L. Whipple Observatory 1.5-m telescope (+ FAST), shows it to be a type-Ia supernova around one week before maximum light. Cross-correlation with a library of supernova spectra using the "Supernova Identification" code (Blondin and Tonry 2007, Ap.J. 666, 1024) indicates that 2008dx is most similar to the subluminous type-Ia supernova 2000cn (Matheson et al. 2008, A.J. 135, 1598) at nine days before maximum, at a redshift cz = 10500 ± 1200 km/s. Adopting this recession velocity for the supernova, the maximum absorption in the Si II line (rest 635.5 nm) is blueshifted by roughly 13500 km/s. Assuming that the galaxy is in the Hubble flow and the supernova suffers negligible extinction, the discovery magnitude of 17.4 corresponds to an absolute magnitude of roughly -18.5, which is brighter than that of SN 1991bg and comparable to normal type-Ia supernovae at the same age.