A. J. Castro-Tirado. Y. Hu, E. Fernandez-Garcia (IAA-CSIC), A. Valeev,
V. Sokolov (SAO-RAS), S. Guziy (Univ. of Nikolaev), S. Oates (U.
Warwick) S. Jeong (SKKU), S. B. Pandey (ARIES), I. Carrasco (Univ. de
M��laga) and D. Reverte-Paya (GRANTECAN, IAC, ULL), on behalf of a larger
"Following the detection of the ultra-bright GRB 190114C (Gropp et al.
GCN 23688, Hamburg et al. GCN 23707), also recorded at very-high
gamma-ray energies (Mirzoyan et al. GCN 23701), optical spectroscopy of
the reported optical afterglow (Gropp et al., GCN 23688; Tyurina et al.
GCN 23690; Lipunov et al. GCN 23693; Selsing et al., GCN 23695; Izzo et
al., GCN 23699; Bolmer et al., GCN 23702) has been undertaken at the
10.4m GTC telescope (+OSIRIS) at the Spanish island of La Palma starting
on Jan 14, 23:32 UT (2.6 hr post-burst). The two spectra (600s each, at
high airmass) covered the range 3,700-9.600 A and the detection of Ca H
& K lines and the Na I doublet (as well as other Fraunhofer lines)
confirms the redshift value reported by Selsing et al. (GCN 23695) which
we refine to z = 0.4245 +/- 0.0005, supporting the association with the
galaxy detected in the Pan-STARRS archival data (de Ugarte Postigo et
al. GCN 23692).
We acknowledge the excellent support of the GTC staff."