GCN Circular 17744
Subject
GRB 150423A: Keck redshift of neighboring galaxy
Date
2015-04-24T09:15:25Z (9 years ago)
From
Daniel Perley at Caltech <dperley@astro.caltech.edu>
D. A. Perley (Caltech) reports:
Further to GCN 17733, I report analysis of the spectroscopy acquired of
S2, the neighboring object located 4.0 arcseconds northeast of the
optical afterglow of GRB 150423A, first announced by Varela et al. (GCN
17732).
The spectrum of this object shows weak emission lines from OII (3727),
OIII (5007), Halpha (6563), and marginally Hbeta (4861), all at a common
redshift of z=0.456. No features are visible in the trace of S1 at any
of the same wavelengths (or elsewhere in its spectrum).
At this redshift, the offset between the sources corresponds to 23 kpc
in projection.
Further observations of S1 will be necessary to determine whether it is
entirely afterglow or if it also contains flux from a (coincident) host
galaxy, perhaps at a different redshift.