{
  "bibcode": "1999GCN...460....1D",
  "body": "GRB 991208 Keck Spectroscopy\n\nA. Diercks, J. S. Bloom, S. G. Djorgovski, L. Hillenbrand, and J.\nCarpenter (Caltech) report on behalf of the Caltech-NRAO-CARA GRB\ncollaboration:\n\n\"A 1500-s spectrum of the afterglow of GRB 991208 (GCN #450; GCN #451; GCN\n#452) was obtained on the night of 14 Dec 1999 UT at the Keck II 10-m\nTelescope on Mauna Kea by L. Hillenbrand and J. Carpenter (Caltech). The\nobservations were conducted using the Low-Resolution Imaging Spectrometer\n(LRIS; Oke et al. 1995) with a 400 line/mm grating blazed at ~8500 Ang\ngiving an effective wavelength coverage of ~6250 - 9050 Ang.  A\npreviously-measured instrument response function was used for an\napproximate flux calibration.\n\nInterestingly, the spectrum appears very blue, in contrast with\ntheoretical expectations for an afterglow.  Though the spectrograph slit\nwas aligned close to the parallactic angle, the observations were\nperformed at an airmass of ~3.6 and with a bright dawn sky foreground.  \nHowever, we do not think that the observed spectral slope can be entirely\nexplained by the differential slit losses.  The extreme blueness is so\npuzzling that we strongly encourage multiband photometric or additional\nspectrophotometric observations to check this potentially interesting\nresult.\n\nThis message may be cited.\"",
  "circularId": 460,
  "createdOn": 945239837000,
  "email": "jsb@astro.caltech.edu",
  "subject": "GRB 991208 Keck Spectroscopy",
  "submitter": "Josh Bloom at CIT  <jsb@astro.caltech.edu>",
  "eventId": "GRB 991208"
}