SIMBAD references

S. Blondin, Harvard-Smithsonian Center for Astrophysics (CfA), on behalf of the CfA Supernova Group, reports that a spectrogram (range 350-740 nm) of 2008bt (cf. CBET 1336), obtained by M. Calkins on Apr. 15.16 UT 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 2008bt is most similar to the sub-luminous type-Ia supernova 1991bg at 3 days past maximum. Adopting a recession velocity of 4551 km/s for the host galaxy (from Fairall et al. 1992, A.J. 103, 11), the maximum absorption in the Si II line (rest 635.5 nm) is blueshifted by roughly 10300 km/s. Assuming that the galaxy is in the Hubble flow and the supernova suffers negligible extinction, the discovery magnitude of 16.6 corresponds to an absolute magnitude of roughly -17.5, comparable to SN 1991bg at the same age. Also, interstellar Na I D absorption at the redshift of the host galaxy is visible in the spectrum with an equivalent width of 0.2 nm.