{
  "bibcode": "2017GCN.21197....1I",
  "body": "L. Izzo, Z. Cano (IAA-CSIC), A. de Ugarte Postigo (IAA-CSIC, DARK/NBI), D.\nA. Kann (IAA-CSIC), C. C. Thoene (IAA-CSIC), A. Marante (GTC) and S. Geier\n(GTC, IAC) report on behalf of a larger collaboration:\n\nWe observed the afterglow of GRB 170604A (Page et al., GCN Circ. 21191)\nusing OSIRIS at the 10.4 m GTC telescope at La Palma (Spain). The\nobservation consisted of 2x900s and 1x1200s exposures using the R1000B\ngrism, which covers a wavelength range of 3700-7880 AA.  Observations began\nat 04:14:19 UT on the morning of 05 June, 2017, at a mean epoch of +9.51\nhrs from the GRB detection.  The afterglow candidate (Izzo et al, GCN Circ.\n21192) is detected in the r-band acquisition image, where we measure r =\n20.3 +- 0.1 relative to nearby PANSTARRS standards in the GRB field of\nview.\n\nThe afterglow spectrum shows a continuum through the observed wavelength\nrange, and we identify absorption features corresponding to MgII, MgI, and\nFeII at a common redshift of z=1.329, which we identify as the redshift of\nGRB 170604A.",
  "circularId": 21197,
  "createdOn": 1496649841000,
  "email": "zewcano@gmail.com",
  "subject": "GRB 170604A: GTC spectroscopic redshift",
  "submitter": "Zach Cano at U of Iceland  <zewcano@gmail.com>",
  "eventId": "GRB 170604A"
}