TITLE:   GCN CIRCULAR
NUMBER:  6864
SUBJECT: GRB 071010: Keck/LRIS Spectroscopy
DATE:    07/10/10 07:56:39 GMT
FROM:    Jason Prochaska at UCO/Lick Obs  <xavier@ucolick.org>

Jason X. Prochaska (UCSC), D. A. Perley, M. Modjaz, J.S. Bloom,
D. Poznanski (UC Berkeley), H.-W. Chen (U Chicago), report on behalf  
of GRAASP:

"We observed the afterglow of GRB 071010 with the LRIS
dual spectrometer for a series of 900s exposures starting
at UT 05:00 under good conditions.  Analysis of the blue side
reveals a strong MgII absorber and corresponding FeII lines
at z=0.98.  The absence of strong features in the spectrum
redward of 5700A suggests this is the redshift of
the GRB.  A more conservative upper limit is placed by
the absence of IGM signatures at 3400A which
indicates z_GRB < 1.8.

Further analysis is in progress."


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