2009CBET.1789....1A

J. Anderson, N. Morrell, G. Folatelli, and M. Stritzinger, on behalf of the Millennium Center for Supernova Science and the Carnegie Supernova Project, report that they obtained spectra (range 388-942 nm) of 2009dp (cf. CBET 1779), 2009dq (cf. CBET 1781), 2009ds (cf. CBET 1784, 1788), and 2009dt (cf. CBET 1785) on Apr. 30.1-30.4 UT with the Magellan II Clay 6.5-m telescope (+ LDSS3) at Las Campanas Observatory.

SN 2009dp is a type-Ic 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) provides matches to spectra of SN 1994I and SN 1990aa at maximum light, although the prominent absorption at 750 nm due to O I is absent in the spectrum of SN 2009dp.

SN 2009dq is a type-IIb supernova around maximum light. SNID provides matches with spectra of SN 1996cb at -2 and +1 days. H-alpha appears prominently with a P-Cyg profile; from its absorption minimum, and adopting a recession velocity of 1397 km/s for the host galaxy (cf. H I Parkes All Sky Survey Final Catalogue, 2006), an expansion velocity of about 14000 km/s is derived. H-beta is not detected.

SN 2009ds is a type-Ia supernova around a week or more before maximum light. The best SNID matches correspond to spectra of SN 2003du at -10 and -7 days and of SN 1990N at -6 days. The supernova presents a very weak Si II 597.2-nm line. Adopting a recession velocity of 5774 km/s for the host galaxy (cf. de Vaucouleurs et al. 1991, Third Reference Catalogue of Bright Galaxies, ver. 3.9), expansion velocities of 14200 and 15500 km/s are derived from the absorption minima of the Si II 635.5-nm and 587.2-nm lines, respectively. Although its continuum is quite blue, the spectrum shows interstellar Na I D in absorption with an equivalent width of 0.13 nm, suggesting that 2009ds may suffer from significant reddening.

SN 2009dt is a type-Ic supernova near maximum light. According to SNID, its spectrum is most similar to those of SN 2004aw between -2 and +2 days.