GCN Circular 26405
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 Gaia19fmm (AT2019wfa, Kostrzewa-Rutkowska et al. GCNC 26397) 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) starting on Dec 12, 21:00 UT. For Gaia19fmm/AT2019wfa a magnitude r' = 18.01 +/- 0.02 on MJD 58829.8727669 is derived. The GTC spectrum is consistent with a SN Ia 3-4 days before maximum at redshift z = 0.0599 +/- 0.0005 derived from the emission lines of the host galaxy. Therefore we consider that Gaia19fmm/AT2019wfa is unrelated to the S191205ah GW alert.