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Spectroscopic Classification of SN 2017gfj as a Type Ia Supernova

ATel #10663; Jujia Zhang (YNAO) and Xiaofeng Wang (Tsinghua University)
on 23 Aug 2017; 14:30 UT
Distributed as an Instant Email Notice Supernovae
Credential Certification: Ju-Jia Zhang (jujia@ynao.ac.cn)

Subjects: Optical, Supernovae

We obtained an optical spectrum (range 350-900 nm) of SN 2017gfj on UT Aug. 22.7 2017 with the 2.4 m telescope ( LJT + YFOSC) at LiJiang Observatory of Yunnan Observatories (YNAO). The spectrum is consistent with that of a type Ia supernova at around the maximum light. Cross-correlation with a library of supernova spectra using the "Supernova Identification" code (SNID; Blondin and Tonry 2007, ApJ, 666, 1024) shows that it matches with SN 1994ae at t = +0 days from the maximum light. Note that the redshift of this supernova is estimated to be about 0.072 from the SNID fit, which is apparently larger than the redshift of the proposed host galaxy UGC 11950 (z~0.0205). This indicates that its host galaxy should be very faint and at a much larger distance. After correcting for a redshift of 0.072, an expansion velocity of about 10500 km/s can be derived from the absorption minimum of Si II 635.5 nm.