Spectroscopic classification of three supernovae at Asiago

ATel #4260; L. Tomasella, S. Benetti, E. Cappellaro, P. Ochner, A. Pastorello, M. Turatto, and S. Valenti (Osservatorio Astronomico di Padova, Istituto Nazionale di Astrofisica)
on 17 Jul 2012; 08:45 UT
Distributed as an Instant Email Notice Supernovae
Credential Certification: Stefano Benetti (stefano.benetti@oapd.inaf.it)

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We report the spectroscopic confirmations of three transients on observations taken with the 1.82-m Copernico Telescope (+ AFOSC; range 340-820 nm, resolution 2.4 nm). A spectrogram of CSS120620:135635+044652 obtained on Jun. 16.91 UT suggests that this is a normal type-Ia supernova. Cross-correlation with a library of supernova spectra via the "Supernova Identification" code (SNID; Blondin and Tonry 2007, Ap.J. 666, 1024) shows that the transient is similar to several Ia-normal SNe about two weeks after maximum at a redshift ~0.054. A noisy spectrogram of PSN J16003509+1541043 obtained on Jun. 16.95 UT suggests that this is a type-Ib supernova. Cross-correlation with a library of supernova spectra via the "Supernova Identification" code (SNID; Blondin and Tonry 2007, Ap.J. 666, 1024) shows that the transient is similar to several Ib-normal SNe not far from maximum at a redshift ~0.038 (in agreement with that reported by Haynes et al 1997, AJ 113, 119, via NED). The spectrum is dominated by a broad P-Cyg line centered at about 600 nm. If we assume it is due to HeI 587.6 nm transition from its minimum an expansion velocity of about 8800 km/s is derived for the ejecta. A spectrogram of PSN J07545548+7236346 obtained on Jun. 17.08 UT suggests that this is a type-Ia supernova. Adopting for the host galaxy UGC 4067 a redshift z = 0.0115 (De Vaucouleurs et al 1991, RC3.9, via NED) the comparison with a library of supernovae spectra via GELATO (Harutyuyan et al. 2008, A.Ap. 488, 383) shows that it is a type Ia event at about one month after maximum.