GCN Circular 7587
Subject
GRB 080411: VLT redshift
Event
Date
2008-04-12T01:51:01Z (18 years ago)
From
Daniele Malesani at Niels Bohr Inst,Dark Cosmology Center <malesani@astro.ku.dk>
Christina C. Thoene (DARK/NBI), Annalisa De Cia (Univ. Iceland), Daniele
Malesani, and Paul M. Vreeswijk (DARK/NBI), report:
We observed the optical afterglow of GRB 080411 (Marshall et al., GCN
7584; Kruehler et al., GCN 7586) wih the ESO VLT equipped with FORS1
with grism 300V. In a 600 s exposure taken at large airmass (average of
2.45) the afterglow trace is clearly detected. The mean time of the
observations is Apr 11.987 UT (2.4 hr after the trigger). In the
acquisition image, we measure R = 17.25 based on archival zeropoints.
We detect very strong absorption lines from Mg II, Mg I, Fe II and
several other ions at a redshift z = 1.03. Given the strength of the
features, we consider this to be the redshift of the GRB. We caution
that the wavelength calibration is based on archival data.
We acknowledge excellent support from the ESO staff, who carried out
this difficult observation, in particular Swetlana Hubrig.