SIMBAD references

D. D. Balam, Dominion Astrophysical Observatory, National Research Council of Canada (NRCC); M. L. Graham, Las Cumbres Observatory Global Telescope, University of California at Santa Barbara; E. Y. Hsiao, Lawrence Berkeley Laboratory; G. Sarty, University of Saskatchewan; and D. W. E. Green, Harvard University, report that a spectrogram (range 382-714 nm, resolution 0.3 nm) of PSN J19273364+5423113 = SN 2011df, obtained on May 28.36 UT with the 1.82-m Plaskett Telescope of the National Research Council of Canada, shows it to be a type-Ia supernova 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 2011df is most similar to the type-Ia supernova 1989B a few days before maximum light.