TITLE:   GCN CIRCULAR
NUMBER:  7849
SUBJECT: GRB 080607: Keck/LRIS spectroscopy and redshift
DATE:    08/06/07 07:47:19 GMT
FROM:    Daniel Perley at U.C. Berkeley  <dperley@astro.berkeley.edu>

J. X. Prochaska (UCO/Lick), J. Shiode, J. S. Bloom, D. A. Perley, A. A. 
Miller, J. Shiode, D. Starr, R. Kennedy, and J. Brewer (UC Berkeley) report:

Upon receiving the GCN alert we immediately slewed with Keck I (+LRIS) 
to the field of GRB 080607 (GCN 7847, Mangano et al.).  The optical 
transient (GCN 7846, Rujopakarn et al.) was visually identified on the 
guider.  Spectroscopic observations began at 06:20:35 UT, 13 minutes 
after the trigger, using the 600 and 400 line gratings on the blue and 
red cameras, respectively, for wavelength coverage between 3000-9300 A.

Our preliminary reduction of the LRIS-b spectrum reveals a very strong, 
damped Lya profile and metal-line transitions of OI, SiII, CII, SiII* 
among others.  These establish the redshift of the GRB to be z=3.036.