[vsnet-grb-info 14886] GRB 140428A: Keck redshift estimate
GCN Circulars
gcncirc at capella2.gsfc.nasa.gov
Tue Apr 29 17:49:58 JST 2014
TITLE: GCN CIRCULAR
NUMBER: 16181
SUBJECT: GRB 140428A: Keck redshift estimate
DATE: 14/04/29 08:49:50 GMT
FROM: Daniel Perley at Caltech <dperley at astro.caltech.edu>
D. A. Perley (Caltech) reports:
I re-observed the afterglow candidate of GRB 140428A in longslit mode
using LRIS on the Keck I 10m telescope. One 940-second exposure was
taken using the 400/8500 grating (red camera) and 600/4000 grism (blue
camera).
In a provisional reduction, the spectrum of the object shows a weak,
flat continuum between 7000 Angstroms and the red limit of the
wavelength range at approximately 10100 Angstroms. The flux sharply
drops to zero at 7000 angstroms, though there is faint flux detected in
some places slightly further to the blue. No trace is detected on the
blue camera.
If the drop at 7000 Angstroms is interpreted as a DLA and the onset of
the Lyman-alpha forest, this would indicate a redshift for this object
of approximately z=4.7.
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