2011CBET.2739....1T

L. Tomasella, P. Ochner, S. Valenti, and S. Benetti, Istituto Nazionale di Astrofisica, Osservatorio Astronomico di Padova; and A. Pastorello, Dipartimento di Astronomia, Universita di Padova, on behalf of a larger collaboration, report that a spectrogram (range 390-810 nm; resolution 2.2 nm) of SN 2011dc (cf. CBET 2726), obtained on June 7.00 UT with the Ekar-Copernicus 1.82-m telescope (+ AFOSC), confirms that it is a type-I supernova. The spectrum shows strong features of helium at 587.6 and 667.8 nm, typical of type-Ib supernovae after maximum. Cross-correlation of the observed spectrum with a library of supernova spectra using the "GELATO" code (Harutyunyan et al. 2008, A.Ap. 488, 383, available at https://gelato.tng.iac.es/login.cgi) shows that SN 2011dc is similar to 1999dn at one week after maximum (Benetti et al. 2011, MNRAS 411, 2726).