GCN Circular 8304
Subject
GRB080928: redshift retraction
Event
Date
2008-10-01T15:53:55Z (18 years ago)
From
Antonino Cucchiara at PSU <cucchiara@astro.psu.edu>
A. Cucchiara and D. B. Fox (Penn State) report on behalf of a larger
collaboration:
We re-processed the data acquired on GRB080928 in order to reconcile our
results
with the redshift identification reported by Vreesvijk et al. (GCN 8301).
Upon comparison of our two individual exposures, we cannot confirm the
presence
of the metal absorption features reported in GCN 8300. We therefore
conclude that
the redshift z=2.49 for GRB 080928 reported by us previously is not
correct. Line
misidentifications are probably the result of inaccurate sky-line and
sky-fringe
modeling in extraction of the 1D spectrum. We retract also the claim of
a DLA
system at z~2.5.
We confirm the detection of strong MgII doublet and associated MgI
absorption from
a system at z=1.69, which - as reported by Vreeswijk et al. - represents
the lower
limit and most likely redshift for GRB 080928.
We apologize for any confusion.