LIGO/Virgo S190910d: WHT spectroscopy of ZTF19abyfhov, ZTF19abyfhaq, ZTF19abyfbii

We obtained optical spectroscopy of ZTF19abyfhov/AT2019pvu, ZTF19abyfhaq/AT2019pvv and ZTF19abyfbii/AT2019pvz (GCN 25706), three optical transients within the LIGO/Virgo S190910d sky localisation (GCN 25695) with the ACAM instrument mounted on the William Herschel Telescope located at the Roque de Los Muchachos Observatory, La Palma, Spain. We cross-correlate the transient spectra with a library of supernova template spectra using the code SNID (Blondin and Tonry, 2007). ZTF19abyfhov/AT2019pvu is classified as a SNIa, 3 days before peak, at redshift z=0.132. The spectrum of ZTF19abyfhaq/AT2019pvv has a low SNR, preventing a precise classification. ZTF19abyfbii/AT2019pvz is classified as a SNIa 91T-like, 5 days before peak, at redshift z=0.118. This redshift is consistent with the photometric redshift reported in GCN 25706.