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Spectroscopic Classification of SN 2017ghm as a Type Ia Supernova

ATel #10691; J. Vinko (Konkoly Observatory; U Szeged; UT Austin),. J. C. Wheeler (UT Austin), X. Wang, W. Li, Z. Li, D. Xiang, L. Rui, H. Lin (Tsinghua University), Z. Xu, B. Li, H. Zhao (PMO), L. Wang (PMO/TAMU), H. Tan (Chinese Culture University), J. Zhang (YNAO)
on 1 Sep 2017; 06:52 UT
Credential Certification: Jozsef Vinko (vinko@astro.as.utexas.edu)

Subjects: Optical, Supernovae

An optical spectrum (range 360-680 nm) of SN 2017ghm (=PTSS-17uyml), discovered by the PMO-Tsinghua Supernova Survey (PTSS, http://www.cneost.org/ptss/ ), was obtained with the new "Low Resolution Spectrograph-2" (LRS2) on the 10m Hobby-Eberly Telescope at McDonald Observatory by S. Rostopchin on 2017 Aug 31.17 UT.

The spectrum is consistent with that of a heavily reddened Type Ia supernova (with Av > 2.3 mag) around 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 2007af at about 3 days after maximum light. After correcting for a redshift of 0.023 measured from the narrow emission lines if the host galaxy, an expansion velocity of about 9800 km/s can be derived from the absorption minimum of the Si II 635.5 nm line. Our classification spectrum is also posted on the IAU Transient Name Sever: