{
  "bibcode": "1999GCN...481....1D",
  "body": "GRB 991208 Keck Spectroscopy\n\nS. G. Djorgovski, A. Dierks, J. S. Bloom, S. R. Kulkarni (Caltech),\nA. V. Filippenko (UC Berkeley), L. A. Hillenbrand, and J. Carpenter \n(Caltech), report on behalf of the Caltech-CARA-NRAO GRB collaboration:\n\nWe recalibrated and combined the Keck spectra of GRB 991208 obtained on\n14 and 15 Dec 1999 UT, for which preliminary results were reported earlier \n(GCN #460, GCN #464).  Addition of the spectra improved the total S/N as\nexpected.  We confirm the existence of emission lines at the observed \nwavelengths 6356, 8454, and 8545 Ang, reported by Dodonov et al. (GCN #475).  \nWe agree with their proposed identifications as [O II] 3727, and [O III] \n4959, 5007, giving the redshift z = 0.7055 +- 0.0005.  However, we note \nthat the proximity of the strong night sky lines (especially for the \ntentative 8454 Ang line), and additional spectroscopic observations are \nstill needed in order to firm up this result.\n\nAssuming z = 0.7055, and the standard Friedmann cosmology with h = 0.65,\nOmega_0 = 0.2, and Lambda_0 = 0, the luminosity distance is 1.30E28 cm.\nAssuming the integrated gamma-ray fluence of >~ 1.E-4 erg/cm2 (GCN #450), \nthe implied isotropic energy is ~ 1.3E53 erg, which of course may be\naffected by beaming.\n\nWe also performed a power-law fit to the fully calibrated and extinction\ncorrected spectrum from UT Dec. 15.64.  For F_nu ~ nu ** beta, we obtain \nbeta = -0.9 +- 0.15, in a good agreement with the photometric measurement \nreported by Bloom et al. (GCN #480).\n\nThis message may be cited.",
  "circularId": 481,
  "createdOn": 945480349000,
  "email": "george@oracle.caltech.edu",
  "subject": "GRB 991208 Keck Spectroscopy",
  "submitter": "George Djorgovski at Caltech/Palomar  <george@oracle.caltech.edu>",
  "eventId": "GRB 991208"
}