[AAVSO-HEN] GRB 080805: VLT redshift update

[grb at aavso.org]

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TITLE:   GCN CIRCULAR
NUMBER:  8077
SUBJECT: GRB 080805: VLT redshift update
DATE:    08/08/08 18:23:14 GMT
FROM:    Pall Jakobsson at U Hertfordshire  <P.Jakobsson at herts.ac.uk>

P. Jakobsson (U. Hertfordshire), J. P. U. Fynbo, P. M. Vreeswijk
(DARK/NBI) and A. de Ugarte Postigo (ESO) report on behalf of a
larger collaboration:

We have reduced the VLT spectra presented in Jakobsson et al.
(GCN 8062) with new calibration files and performed a thorough
line search in all four grisms (300V, 1028z, 1200R, 1400V)
covering approximately 3700-9500 A. We confirm the existence
of a line system at redshift z = 1.505 +/- 0.001 displaying
Fe II (2382,2586,2600), the Mg II doublet (2796,2803) and
Mg I (2852). In addition, there is a clear bump (flux decrease)
present between 5300-5600 A that can be interpreted as the
2175 A extinction feature at z ~ 1.5.

Apart from the z = 1.20 redshift system presented in GCN 8062,
no other significant lines are visible. We therefore conclude
that z = 1.505 is the redshift of GRB 080805.