NASA Swift: GRB060522: z = 5.11 Keck-LRIS Redshift

TITLE: GCN GRB OBSERVATION REPORT
NUMBER: 5155
SUBJECT: GRB060522: z = 5.11 Keck-LRIS Redshift
DATE: 06/05/22 22:17:46 GMT
FROM: S. Bradley Cenko at Caltech cenko@srl.caltech.edu

S. B. Cenko (Caltech), E. Berger (Carnegie), S. G. Djorgovski, A. A. Mahabal (Caltech), and D. B. Fox (Penn State) report on behalf of a larger collaboration:

We have observed the location of the afterglow of GRB060522 (Fox et al., GCN 5150; D’Avanzo et al., GCN 5151) with the Low-Resolution Imaging Spectrometer mounted on the 10-m Keck I telescope. We obtained an 1800 s spectrum shortly before morning twilight at a mean epoch of May 22.65 UT (~ 12.5 hr after the burst).

We find a prominent absorption feature centered around ~ 7425 A, with a strong depression in flux blue-ward of this break. Identifying this as the Lyman-alpha break and fitting a DLA profile to the spectrum, we find z = 5.11 +/- 0.01 and log(nH) = 20.5 +/- 0.5.

At this redshift and using a 15-150 keV fluence of 1.1e-6 (Krimm et al., GCN 5153), we find the prompt emission isotropic energy release from GRB060522 is 5.1e52 ergs.