{
  "bibcode": "2016GCN.19773....1X",
  "body": "D. Xu (NAOC), K. E. Heintz (DARK/NBI), D. Malesani (DARK/NBI and DTU \nSpace), K. Wiersema (U. Leicester), J. P. U. Fynbo (DARK/NBI), report on \nbehalf of a larger collaboration:\n\nWe observed the optical afterglow of GRB 160804A (Marshall et al., GCN \n19761; Breeveld et al., GCN 19764) with the ESO VLT UT2 (Kueyen) \nequipped with the X-shooter spectrograph. Observations started at 23:55 \nUT on 2016-08-04 (22.37 hr after the BAT trigger) and consisted of 4 \nspectra by 600 s each, covering the wavelength range 3500-20000 AA.\n\nThe continuum trace is well detected in our exposures, down to ~3100 AA.\nThe lack of any drop sets an upper limit to the redshift z < 1.55. A \nnumber of superimposed absorption features are detected, which we \ninterpret as due to Mg I, Mg II, Fe II, Al II, as well as emission \nfeatures due to [O II], [O III], Halpha, Hbeta, Hgamma, [N II], [S II], \n[S III], all at a common redshift z = 0.736. We thus conclude this is \nthe redshift of GRB 160804A.\n\nWe acknowledge excellent support from the ESO observing staff in \nParanal, in particular Jonathan Smoker, Leo Rivas, and Stephane Brillant.",
  "circularId": 19773,
  "createdOn": 1470384336000,
  "email": "dxu@nao.cas.cn",
  "subject": "GRB 160804A: VLT/X-shooter redshift",
  "submitter": "Dong Xu at NAOC/CAS  <dxu@nao.cas.cn>",
  "eventId": "GRB 160804A"
}