[vsnet-grb-info 6703] GRB080928: redshift retraction

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  8304
SUBJECT: GRB080928: redshift retraction
DATE:    08/10/01 15:53:55 GMT
FROM:    Antonino Cucchiara at PSU  <cucchiara at 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.