[vsnet-grb-info 7689] GRB 090424 Gemini-South Redshift

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  9243
SUBJECT: GRB 090424 Gemini-South Redshift
DATE:    09/04/25 03:02:24 GMT
FROM:    Ryan Chornock at UC Berkeley  <chornock at astro.berkeley.edu>

R. Chornock, D. A. Perley, S. B. Cenko, and J. S. Bloom (UC Berkeley) report on
behalf of a larger collaboration:

We obtained optical spectra of the afterglow of GRB 090424 (Cannizzo et al., GCN
9223) using GMOS on Gemini-South.  Our spectra cover the wavelength range of
4400-8600 angstroms.  Our first 1200s exposure, starting at 01:51:56 April 25 UT
(11.7 hr after the trigger) reveals.a pair of absorption lines at 6077 and 6130
Angs, which we identify as the Ca II H+K doublet at z=0.544.  Additionally, an
emission line is present at 5758 A, which is consistent with the [O II] 3727
doublet at the same redshift, which we therefore identify as the redshift of the
host galaxy.  We note that this redshift is significantly higher than the
photo-z noted by Evans & Holland (GCN 9226).