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Asiago spectroscopic classification of ASASSN-13dm as a type-Ia supernova

ATel #5655; A. Pastorello, M. Turatto, L. Tomasella, P. Ochner, S. Benetti, E. Cappellaro and N. Elias-Rosa (Osservatorio Astronomico di Padova, Istituto Nazionale di Astrofisica)
on 13 Dec 2013; 00:47 UT
Credential Certification: Lina Tomasella (lina.tomasella@oapd.inaf.it)

Subjects: Optical, Supernovae

We report that an optical spectrogram (range 340-820 nm; resolution 1.3 nm) of ASASSN-13dm (Shappee et al. ATel #5654) obtained on Dec. 12.95 UT with the Asiago 1.82-m Copernico Telescope (+ AFOSC), shows it to be a type-Ia supernova. Adopting a redshift z = 0.017 for the host galaxy PGC 2816341 (Miller and Owen 2001, ApJS, 134, 355), a good match is found with the type-Ia supernova 2000E (Valentini et al. 2003 ApJ, 595, 779) at 8-10 days past B-band maximum light. A prominent, narrow interstellar Na I feature is visible at the redshift of the host galaxy, with an equivalent width of 2.5A, suggesting significant internal reddening. Adopting the relation of Turatto et al. (2003, in From Twilight to Highlight: The Physics of Supernovae, ed. W. Hillebrandt & B. Leibundgut -Berlin:Springer-, p.200), we infer an E(B-V) = 0.4 due to the host galaxy. The expansion velocity of the ejecta, as deduced from the position of the minimum of the Si II 6355A line, is 10200 km/s. The Asiago classification spectra are posted at the website URL http://sngroup.oapd.inaf.it. The classification is made via GELATO (Harutyunyan et al. 2008, A.Ap. 488, 383) and SNID (Blondin and Tonry 2007, Ap.J. 666, 1024).