TITLE: GCN CIRCULAR NUMBER: 26422 SUBJECT: LIGO/Virgo S191205ah: AT2019wix and AT2019wib 10.4m GTC spectroscopy DATE: 19/12/14 09:25:02 GMT FROM: Alberto J. Castro-Tirado at IAA-CSIC Y.-D. Hu (IAA-CSIC), A. F. Valeev (SAO-RAS), A. J. Castro-Tirado and E. Fernandez-Garcia (IAA-CSIC), V. Sokolov (SAO-RAS), I. Carrasco and A. Castellon (UMA) and R. Scarpa (GRANTECAN, IAC, ULL), on behalf of a larger collaboration, report: Following the detection of AT2019wix/ZTF19acxoywk and AT2019wib/ZTF19acxowrr (Andreoni et al. GCNC 26416) within the error area of the GW event S191205ah (LVC, GCNC 26350), we obtained optical spectra covering the range 3700-7400 A with the 10.4m GTC telescope equipped with OSIRIS in La Palma (Spain) on Dec 14. It is found that these two transients happened at the same distance. Details follow: For AT2019wix/ZTF19acxoywk,a magnitude r'= 19.58 +/- 0.03 on 04:34UT is derived. The GTC spectrum is consistent with a SN Ib at redshift z = 0.052 +/- 0.003, consistent with the redshift of the host galaxy derived from the emission lines (z = 0.0508 +/- 0.0005). For AT2019wib/ZTF19acxowrr, a magnitude r'= 18.19 +/- 0.01 on 06:10UT is derived. The GTC spectrum is consistent with a SN IIp at redshift z = 0.0509 +/- 0.0005. Therefore we consider that AT2019wix/ZTF19acxoywk and AT2019wib/ZTF19acxowrr are unrelated to the S191205ah GW alert.