[vsnet-grb-info 7132] GRB 081222: Gemini-South absorption redshift

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  8713
SUBJECT: GRB 081222: Gemini-South absorption redshift
DATE:    08/12/23 14:58:35 GMT
FROM:    Antonino Cucchiara at PSU  <cucchiara at astro.psu.edu>

A. Cucchiara, D. B. Fox (Penn State), S. B. Cenko  (Berkeley) and E. Berger
(Harvard) report on behalf of a larger collaboration:

Starting at 01:02 UT on 2008 December 23  we observed the optical
counterpart of GRB 081222 (Grupe et al., GCN 8691, Covino  et al.,
GCN 8692 and Updike et al. 8693) using Gemini-South with the GMOS-South
spectrograph (R~1600).
We acquired 2x900s spectra covering the wavelength range 4000A-8000A.

We detect a damped Lyman-alpha system (DLA) at redshift z=2.77.

We also detect several metal absorption features which we interpret as
SiIV(1393,1402), SiII1526 and 1260, SiII*1264, CII1334, CII*1335,
CIV(1548,1550), FeII1608 and NiII(1454) at the same redshift.

In combination with the strong metal absorption features, the detection of
a DLA at z = 2.77 confirms that this is the redshift of GRB 081222 and its
host galaxy.

We thank the Gemini staff, in particular Henry Lee, for conducting
these observations.