TITLE: GCN CIRCULAR NUMBER: 18925 SUBJECT: GRB 160121A: redshift from the 10.4m GTC DATE: 16/01/22 22:08:42 GMT FROM: Alberto Castro-Tirado at Inst.de Astro. de Andalucia R. Sanchez-Ramirez, S. R. Oates, J. C. Tello (IAA-CSIC Granada), S. Geier (GRANTECAN), P. Tristam (Mt. John Univ. Observatory) and A. J. Castro-Tirado (IAA-CSIC and ISA-UMA) report on behalf of a larger collaboration: We observed the field of GRB 160121A (Hagen et al. GCN 18912) with the 10.4m GTC telescope (+OSIRIS) at La Palma. 6x900s spectra were taken at the position of the optical afterglow, detected by the 1.8m MOA (Oates et al. GCNC 18917), starting at 22:30 UT (i.e. 8.7 h post-burst). We identify Mg II and several Fe-II absorption lines at z = 1.960 which we propose to be the host galaxy redshift. An intervening system at z = 1.645 is also detected.