TITLE:   GCN CIRCULAR
NUMBER:  10946
SUBJECT: GRB 100628A: Keck/LRIS Spectroscopy of Host Galaxy Candidate
DATE:    10/07/08 13:54:02 GMT
FROM:    S. Bradley Cenko at Caltech  <cenko@srl.caltech.edu>

S. B. Cenko, D. A. Perley, J. S. Bloom, A. N. Morgan (UC Berkeley), and A.
Cucchiara (UCB/LBNL/UCSC) report on behalf of a larger collaboration:

We have obtained spectra of the galaxy dubbed "G7" (Berger, GCN 10943)
inside the possible X-ray afterglow error circle (Starling et al., GCN
10941) of the short GRB 100628A (Immler et al., GCN 10895) with the Low
Resolution Imaging Spectrometer mounted on the 10 m Keck I telescope.  Our
observations began at 6:25 UT on 8 July 2010 and cover the wavelength
range from 3500-10000 A.

The spectrum is comprised of a series of narrow emission lines, clearly
resolved into two spatially distinct components and joined by a bridge of
faint continuum emission, possibly indicating an interacting or disturbed
system.  We identify the emission lines in both components as [O II], [O
III], H-alpha, and H-beta at a common redshift of z = 0.102, which we
therefore take to be the redshift of the galaxy "G7".