2009CBET.1768....1H

A. Harutyunyan, Telescopio Nazionale Galileo (TNG); N. Elias-Rosa, Spitzer Science Center, California Institute of Technology; and S. Benetti, Istituto Nazionale di Astrofisica, Osservatorio Astronomico di Padova, report that a spectrogram (range 330-770 nm, resolution 1.1 nm) of 2009dc (cf. CBET 1762), obtained on Apr. 16.22 UT with the TNG (+ DOLORES), shows it to be a type-Ia supernova before maximum light. A comparison with the spectra of SN 2006gz (Hicken et al. 2007, Ap.J. 669, L17) shows that 2009dc reproduces well the same spectral features seen in the pre-maximum spectra of SN 2006gz, including prominent C II lines and a blue continuum. However, SN 2009dc shows a much-lower expansion velocity (about 8700 km/s, as deduced from the Si II 635.5-nm absorption).