LIGO/Virgo G274296: Kanata 1.5m optical spectroscopy of MASTER optical transient

We performed optical spectroscopy of the optical transient MASTER OT J105519.53+365834.1PSN in PGC 032819 (Lipunov et al. GCN 20712) with 1.5-m Kanata telescope at Higashi-Hiroshima Observatory on 2017 Feb 21. The spectrum shows a broad absorption line around 620 nm. The overall features suggest that this PSN is a SN 1991T like bright Type Ia supernova around maximum brightness. A comparison with a library of supernova spectra using GELATO (Harutyunyan et al. 2008, A.Ap. 488, 383) suggests that the spectrum gives a good match to SN 1998es at -3.5 days before B-band maximum.