Spectroscopic classification of 4 supernovae

ATel #4370; S. Benetti, L. Tomasella, E. Cappellaro, A. Pastorello, M. Turatto, S. Valenti (Osservatorio Astronomico di Padova, Istituto Nazionale di Astrofisica)
on 11 Sep 2012; 09:36 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 four transients with observations obtained at the 1.82-m Copernico Telescope in Asiago (+ AFOSC; 350-820 nm, resolution 1.3nm). A spectrogram of PSN J22143782+3257187 obtained on Sept. 10.89 UT suggests that this is a type-Ia supernova. Adopting for the host galaxy PGC68367 a redshift z = 0.028546 (Huchra et al. 2012, ApJS 199, 26 via NED), the comparison with a library of supernova spectra via GELATO (Harutyuyan et al. 2008, A.Ap. 488, 383) shows that it is a type Ia event similar to several type-Ia supernovae two weeks after maximum light. The expansion velocity measured from the Si-II 635.5 nm minimum is about 13100 km/s which places it among the high-velocity gradient SN-Ia (Benetti et al, 2005, ApJ 623, 1011). The spectrum also shows an intense NaID interstellar absorption (EW~0.31 nm). A spectrogram of PSN J22440166+1551493 obtained on Sept. 10.95 UT shows it to be a peculiar type-Ia supernova. Adopting for the host galaxy PGC69614 a redshift z = 0.038073 (Kochanek et al. 2001, ApJ 560, 566 via NED), the comparison with a library of supernova spectra via GELATO (Harutyuyan et al. 2008, A.Ap. 488, 383) shows that it is a type Ia event similar to several sub-luminous type-Ia supernovae (SN1991bg-like) around maximum light. The expansion velocity measured from the Si-II 635.5 nm minimum is about 10100 km/s. A spectrogram of CSS120828:231622+241519 obtained on Sept. 11.01 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 this transient is similar to several Ia-normal SNe two weeks after maximum at a redshift of about 0.1. A spectrogram of PSN J04072528+0145333 obtained on Sept. 11.13 UT indicates that it is a type-Ia supernova. Adopting for the host galaxy PGC14498 a redshift z = 0.017295 (Saunders et al. 2000, MNRAS 317, 55 via NED), the comparison with a library of supernova spectra via GELATO (Harutyuyan et al. 2008, A.Ap. 488, 383) indicates that it is a type Ia event around one month after maximum light.