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GCN Circular 3368

GRB 050505: Keck absorption spectrum and redshift (z=4.27)
2005-05-06T08:36:50Z (19 years ago)
Edo Berger at Carnegie Obs <>
Edo Berger (Carnegie Observatories), S. Bradley Cenko, Chuck Steidel,
Naveen Reddy, and Derek B. Fox (Caltech) report on behalf of the
Caltech-NRAO-Carnegie GRB Collaboration:

"We obtained a 900-sec spectrum of the optical candidate (GCN 3366) of GRB
050505 (GCN 3360) with LRIS on the Keck I 10-m telescope on 2005, May 6.27
UT.  We find very strong absorption over the range of 6200-6500 A,
corresponding to Ly alpha absorption around z = 4.1 to 4.3.  In addition,
we find several metal absorption lines, including SiIV (1393,1402), at a
redshift of 4.27.

At this redshift, the second highest measured for any GRB, the isotropic
equivalent gamma-ray energy is 7.7e53 erg."
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