TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  1569
SUBJECT: GRB021004: Absorption redshift
DATE:    02/10/04 19:11:29 GMT
FROM:    Derek Fox at CIT  <derekfox@astro.caltech.edu>

D.W. Fox, A.J. Barth, A.M. Soderberg, and P.A. Price (Caltech), with
H. Buttery (Cambridge) and T. Mauch (U. Sydney), report on behalf of
the Caltech-NRAO GRB Collaboration:

"We have observed the optical afterglow (Fox, GCN 1564) of GRB021004
(Shirasaki et al., GCN 1565) with the Siding Springs Observatory 2.3m
telescope and double-beam spectrograph.  Reduction of a single 1200s
spectrum of the source reveals two distinct absorption-line systems,
with redshifts and line identifications as follows:

    Line       Rest Wavelength (Ang)    Redshift
  ================================================
    Mg II      2796.4, 2803.5           1.38
    Mg II      2796.4, 2803.5           1.60
    Mg I       2853.0                   1.60
  ================================================

We have also identified Mn II and Fe II absorption features associated
with the z=1.60 system.  We conclude that the redshift of GRB021004 is
greater than or equal to 1.60."