{
  "bibcode": "2007GCN..6071....1F",
  "body": "D. B. Fox (PSU), E. Berger (Carnegie), P. A. Price (Hawaii) and\nS. B. Cenko (Caltech) report on behalf of a larger collaboration:\n\n\"We observed the optical afterglow (Cenko & Fox, GCN 6028) of GRB\n070125 (Hurley et al., GCN 6024) with the Gemini-North telescope +\nGemini Multi-Object Spectrograph in four 1800-s integrations with mean\nepoch 06:16 UT on 26 Jan 2007 (approximately 23 hours post-burst).\nOur spectral coverage is 6000-10,000 A for the first hour and\n4000-8000 A for the second hour.\n\nWe confirm the absence of prominent absorption features noted in\ncontemporaneous optical spectra from the Lick 3m (Prochaska et al.,\nGCN 6031) and Keck-I (Prochaska et al., GCN 6032) telescopes.\n\nAt the same time, we identify a single weak (EW < 1 A) absorption\ndoublet at observer-frame wavelengths 7122.9 A + 7140.9 A.  Distinct\ncomponents of the doublet are well detected in separate spectra from\nthe first and second hour of observations, and the relative strength\nof the two systems is consistent with their identification as the Mg\nII (2796.4 A, 2803.5 A) doublet in absorption at redshift z=1.547.\n\nWe therefore conclude that GRB 070125 is at redshift z>1.547.  As\nnoted by Prochaska et al. (GCN 6032), the absence of Lyman-alpha\nforest absorption at short wavelengths simultaneously suggests that\nthe burst redshift is not much greater than this.\"",
  "circularId": 6071,
  "createdOn": 1170537185000,
  "email": "dfox@astro.psu.edu",
  "subject": "GRB 070125: Redshift z>~1.54 from Gemini Afterglow Spectrum",
  "submitter": "Derek Fox at PSU  <dfox@astro.psu.edu>",
  "eventId": "GRB 070125"
}