SIMBAD references

S. Blondin, M. Modjaz, R. Kirshner, and P. Challis, Harvard-Smithsonian Center for Astrophysics, report that a spectrum (range 350-740 nm) of SN 2006bk (cf. CBET 462, CBET 475), obtained on Apr. 21.31 UT by W. Peters with the F. L. Whipple Observatory 1.5-m telescope (+ FAST), shows it to be a type-Ia supernova, roughly three weeks past maximum light. SN 2006bk was classified as a type-Ic supernova around maximum light in CBET 475, on the basis of a "W-shaped" feature around 500 nm. This feature is due to unresolved blends of Fe II lines, and is common to both type-Ia and type-Ic post-maximum spectra – hence the possible confusion. However, cross-correlation with a library of supernova spectra shows that SN 2006bk is similar to the type-Ia supernova 1997br at 21 days past maximum. The best-match type-Ic spectrum is that of SN 1990B at 28 days past maximum; however, it does not concur well with all the spectral features of SN 2006bk. A comparison plot can be seen at the following URL: http://cfa-www.harvard.edu/oir/Research/supernova/ spectra/sn2006bk_comp.gif