TITLE:   GCN CIRCULAR
NUMBER:  851
SUBJECT: GRB 000926:  Improved Absorber Redshift
DATE:    00/10/14 23:58:55 GMT
FROM:    George Djorgovski at Caltech/Palomar  <george@oracle.caltech.edu>

Sandra M. Castro, S. G. Djorgovski, S. R. Kulkarni, J. S. Bloom, T. J. Galama,
F. A. Harrison (Caltech), and D. A. Frail (NRAO), report on behalf of a
large collaboration:

We analysed high-resolution spectra of the optical afterglow of GRB 000926
kindly obtained at the WMKO Keck-II telescope by L. Cowie, A. Barger, et al.
on UT 2000 September 29.26, using the ESI instrument (an Echelle spectrograph).

Our preliminary analysis yields a single absorption system including the 
following lines: Si II 1526.7, C IV 1548.2 and 1550.5, Al II 1670.8, Si II
1808.0, Al III 1854.7 and 1862.8, Zn II 2026.1, Fe II 2344.2, 2373.7, 2382.8,
2586.6, and 2600.2, Mg II 2796.3 and 2803.5, and Mg I 2853.0.  The mean
redshift is z = 2.0369 +- 0.0007, presumably corresponding to the system
identified by Fynbo et al. (GCN 807) as having z ~ 2.066.  However, we see 
no evidence for any other absorption systems in these data; in particular, 
the ostensible system at z = 1.378 proposed by Fynbo et al. is likely due to
line misidentifications.

We note that the line equivalent widths appear to be unusually strong in
comparison to the general population of metallic line absorbers seen in the
spectra of quasars, suggesting a high column density and/or metallicity of
the intervening gas.  A more detailed analysis is in progress.

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