TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  2599
SUBJECT: GRB040511: Redshift identifcation
DATE:    04/05/14 18:22:00 GMT
FROM:    Edo Berger at Caltech  <ejb@astro.caltech.edu>

E. Berger, D.B. Fox, S.G. Djorgovski (Caltech) with T. Treu and M. Malkan
(UCLA) report:

"We obtained three 900-sec spectra of the GRB 040511 afterglow candidate
(GCN 2597) with the Low Resolution Imaging Spectrometer (LRIS) on the
Keck-I telescope. Inspection of the 2-d spectra reveals two strong
emission lines which we identify as Lyman-alpha and HeII 1640A at a
redshift of 2.63.  We also note a decrease in the continuum flux level
blueward of the line we identify as Ly-alpha, strengthening the
association.  We conclude that this is the likely redshift of the GRB.
The detection of a strong HeII line suggests the presence of a source of
strongly-ionizing photons in the host, e.g. an AGN."