TITLE: GCN CIRCULAR NUMBER: 19245 SUBJECT: GRB 160327A: Imaging and spectroscopy from GTC DATE: 16/03/29 18:18:21 GMT FROM: Antonio de Ugarte Postigo at IAA-CSIC A. de Ugarte Postigo (IAA-CSIC, DARK/NBI), N.R. Tanvir (U. Leicester), Z. Cano (U. Iceland), L. Izzo (U. Roma1), J.P.U. Fynbo (DARK/NBI), R. Sanchez-Ramirez (IAA-CSIC), C.C. Thoene (IAA-CSIC), P. Pesev (GRANTECAN, IAC, ULL) report: We observed the field of GRB 160327A (Racusin, et al., GCN 19235) with OSIRIS mounted on the 10.4 m GTC telescope, located at Roque de los Muchachos Observatory (La Palma, Spain) starting at 00:26 UT on 28th March 2016 (15.17 hr after the burst). In the acquisition image, we identify the afterglow proposed by Golkhou et al. (GCN 19236) and later also observed by Zheng & Filippenko (GCN 19242). At the time of our observation, the object was at a magnitude of i(AB) = 23.89 +/-0.12 (as compared to nearby SDSS stars), with coordinates of (J2000.0, +/-0.5"): R.A.: 09:46:48.56 Dec.: +54:00:46.3 We also note the presence of two other sources within 2.5” of the GRB afterglow: The first one is located at 09:46:48.35, +54:00:47.8 and has a magnitude of i(AB) = 23.76+/-0.11, and the second one is at 09:46:48.55, +54:00:44.2 with a magnitude of i(AB) = 24.24+/-0.15. We suspect that these sources may be contributing to the magnitudes given by Golkhou et al. (GCN 19243), especially in the bluer bands. Spectroscopy of the GRB afterglow and the first of the two other objects was obtained by exposing 3x1200 s with grism R1000R, which covers between 5100 and 10100 Angstrom. We detect a trace of the GRB afterglow above 7300 AA, below which the emission drops abruptly. The other object shows a continuum over the complete spectral range, suggesting that this object is unrelated to the GRB. The afterglow spectrum is indicative of a Lyman-alpha drop at a redshift between 4.90 and 5.01, with a most probable value at z = 4.99, although even lower redshifts could not be discarded for unusually large Hydrogen column densities. Due to the low S/N of the spectrum we are not able to confirm any other absorption lines at this time.