2011CBET.2729....3L

Q. Liu and X. Wang, Tsinghua Center for Astrophysics, Tsinghua University: and T. Zhang and C. Wu, National Astronomical Observatories of China (NAOC), report on an optical spectrogram (range 340-850 nm) of PSN J19273364+5423113 = SN 2011df that was obtained on May 27.8 UT with the 2.16-m telescope (+ BFOSC) at the Xinglong Station of the NAOC. The spectrum is consistent with that of a type-Ia supernova at early phase. Cross-correlation with a library of supernova spectra using the "Supernova Identification" code (SNID; Blondin and Tonry 2007, Ap.J. 666, 1024) shows that the spectrum of 2011df matches that of SN 1989B at about one week before maximum. After removal of the host-galaxy recession velocity of about 4300 km/s, they find the absorption minimum of the Si II 635.5-nm line to be blueshifted by about 12500 km/s.