TITLE: GCN CIRCULAR NUMBER: 14790 SUBJECT: GRB 130606A: 10.4m GTC spectroscopy indicates z = 6.1 DATE: 13/06/07 00:06:12 GMT FROM: Alberto Castro-Tirado at Inst.de Astro. de Andalucia A. J. Castro-Tirado, R. Sánchez-Ramírez, M. Jelinek (IAA-CSIC), J. Gorosabel (EHU-UPV), J. C. Tello, P. Ferrero, O. Lara-Gil, R. Cunniffe (IAA-CSIC), D. Pérez-Ramírez (U. Jaén), P. Kubanek (FZU), J. M. Castro Cerón (ESAC), A. Fernández-Soto (UV), S. Mottola (DLR), S. Hellmich (DLR), R. Fernández-Muñoz (EELM-CSIC), V. F. Muñoz-Martínez (UMA), J. Cepa (IAC) and C. Álvarez-Iglesias (GTC), on behalf of a larger collaboration, report: “Following the detection of the optical afterglow (Jelinek et al. GCNC 14782, Xu et al. GCNC 14783) to GRB 130606A ((Ukwatta et al. GCNC 14781), we have obtained an optical spectrum with the 10.4 m GTC (+OSIRIS) starting aprox. 1.5 hr postburst, covering the 4000-10000 wavelength range. The continuum is detected only redwards of aprox. 6500 A, with multiple absorption lines which are indicative of the Lyman forest. Therefore we infer a (preliminary) redshift of z = 6.1 (to be refined). This is consistent with the dropout in the optical band (Virgili et al. GCNC 14785) and the bright nIR afterglow (Nagayama et al. GCNC 14784). Observations at all wavelengths are encouraged.”