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Spectroscopic Classification of ASASSN-15sf as a Type Ia Supernova Before Peak

ATel #8230; Jujia Zhang (Yunnan Observatories), J. L. Prieto (Diego Portales; MAS), Subo Dong (KIAA-PKU)
on 30 Oct 2015; 17:02 UT
Distributed as an Instant Email Notice Supernovae
Credential Certification: Krzysztof Stanek (stanek.32@osu.edu)

Subjects: Optical, Supernovae

We report an optical spectrum (range 350-900 nm) of ASASSN-15sf (ATel #8226) obtained on UT 2015 Oct. 20.7 with the 2.4-m telescope (+YFOSC) at LiJiang Observatory of Yunnan Observatories. The spectrum is consistent with a type Ia supernova a few days before the maximum light. Cross-correlation with a library of supernova spectra using the "Supernova Identification" code (SNID; Blondin and Tonry 2007, Ap.J. 666, 1024) shows that it matches with SN 2005cf at t = -4 days. Adopting a redshift of 0.027 from the SNID fit, an expansion velocity of ~10700 km/s can be derived from the absorption minimum of Si II 635.5 nm.