{
  "bibcode": "1999GCN...251....1D",
  "body": "GRB 990123: Updated Keck Spectroscopy Results\n\nS. G. Djorgovski, S. R. Kulkarni (CIT), G. D. Illingworth (UCSC),\nD. D. Kelson (DTM), J. S. Bloom, S. C. Odewahn, R. R. Gal (CIT), \nM. Franx (Leiden), P. van Dokkum (Groningen), D. Magee (UCSC), and \nD. A. Frail (NRAO) note on behalf of the Caltech-UC-CARA-NRAO \ncollaboration:\n\nOur re-reduction of the Keck spectrum of the optical transient associated\nwith GRB 990123 (Kelson et al., IAUC 7096) gives the following results:\n\nWe detect 12 (13) absorption lines in the spectrum of the OT, as follows:\n\n W_obs,air  W_rest,vac   z    Line ID\n\n  4843.74   1862.78   1.6010   Al III \n  5267.29   2026.14   1.6004   Zn II \n  5361.77   2062.23   1.6007   Cr II | blend\n  5361.77   2062.66   1.6002   Zn II |\n  5877.17   2260.78   1.6003   Fe II \n  6096.14   2344.21   1.6012   Fe II \n  6173.87   2373.73   1.6016   Fe II \n  6195.29   2382.76   1.6008   Fe II \n  6725.75   2586.64   1.6009   Fe II \n  6759.94   2600.18   1.6005   Fe II \n  7269.47   2796.35   1.6003   Mg II \n  7289.49   2803.53   1.6008   Mg II \n  7416.97   2852.97   1.6005   Mg I \n\nThe mean redshift is 1.6004 +- 0.0005 (random) +- 0.0005 (systematic).\nThis agrees to within the quoted error with the new determination of\nthe absorber redshift by Hjorth et al. (GCN 249).\n\nWe note the remarkably small velocity dispersion implied by these data,\nless than about 60 km/s in the restframe, suggesting that the lines arise \nfrom a single subgalactic-size cloud (which of course may be a part of the \nhost galaxy's ISM), rather than from an ansamble of clouds moving within \nthe potential well of a normal, massive galaxy.  It is also possible that \nthe GRB host is a dwarf galaxy, in which case the object detected near the \nline of sight both in the K band (Djorgovski et al., GCN 243) and in the \nR band (Yadigaroglu and Halpern, GCN 248) may be a foreground galaxy.\n\nNo other convincing absorption systems, and no emission lines are detected\nin these data, in the useful wavelength range of approximately 4700 to 9000\nAngstroms.  We do not detect Ca II H+K absorption, nor any other common\nabsorption lines, e.g., Na D, nor any common emission lines (e.g., [O II] \n3727, H alpha, H beta, etc.) from either of the two absorption systems \noriginally proposed by Hjorth et al. (GCN 219).\n\nWe have also measured the redshift of the galaxy approximately 10 arcsec\nwest of the OT.  From 4 relatively \"clean\" lines, Ca II H+K, H beta, and\nH alpha, we derive for its redshift z = 0.2783 +- 0.0005.  From 4 blended\nlines, CH G-band 4300, Mg I 5173+5184, Fe I + Ca I 5267, and Na D 5893,\nwe derive z = 0.278 +- 0.001, again in an excellent agreement with Hjorth\net al. (GCN 249).  No absorption or emission lines corresponding to this \nredshift are seen in the spectrum of the OT.  \n\nThis report may be cited.",
  "circularId": 251,
  "createdOn": 918181878000,
  "email": "george@oracle.caltech.edu",
  "subject": "GRB 990123: Updated Keck Spectroscopy Results",
  "submitter": "George Djorgovski at Caltech/Palomar  <george@oracle.caltech.edu>",
  "eventId": "GRB 990123"
}