TITLE: GCN CIRCULAR NUMBER: 12431 SUBJECT: GRB 111008A: VLT/X-shooter spectroscopy DATE: 11/10/09 11:03:04 GMT FROM: Daniele Malesani at Dark Cosmology Centre, Niels Bohr Inst K. Wiersema (Univ. Leicester), H. Flores (GEPI/Obs. de Paris), V. D'Elia (ASI/ASDC & INAF/OAR), P. Goldoni (APC/Univ. Paris 7 & SAp/CEA), D. Malesani (DARK/NBI), S. D. Vergani (INAF/OABr), A. de Ugarte Postigo (IAA-CSIC), A. J. Levan (Univ. Warwick), B. Milvang-Jensen, J. P. U. Fynbo (DARK/NBI), report on behalf of a larger collaboration: We observed the optical counterpart of GRB 111008A (Saxton et al., GCN 12423; Levan et al., GCN 12426; Xu et al., GCN 12427; Nardini et al., GCN 12428), using the X-shooter spectrograph mounted on the ESO-VLT. Observations started on 2011 October 9.247 UT (7.71 hr after the GRB), with a total exposure time of 2 hr, covering the wavelength range 3000-25000 AA. Continuum is clearly detected redwards of ~7600 AA, with several, strong superimposed absorption features, consistent with a commom redshift z = 4.9898. Among them, we note several Si II and Fe II transitions, the CIV doublet, the Mg II doublet (in the H band), and several fine-structure lines commonly observed in GRB afterglow spectra (such as Si II*, S II*, O I*). We also note the presence of an intervening Mg II system at z = 4.61. Our results are thus consistent with the redshift derived by Levan et al. (GCN 12429; see also Nardini et al., GCN 12428). We acknowledge excellent support from the observing staff in Paranal, in particular Christophe Martayan, Claudio Melo, Leonel Rivas, and Sergio Vera.