GCN Circular 11977
Subject
GRB 110422A: tentative redshift from TNG
Date
2011-04-26T15:51:06Z (13 years ago)
From
Daniele Malesani at Dark Cosmology Centre, Niels Bohr Inst <malesani@dark-cosmology.dk>
D. Malesani (DARK/NBI), D. Fugazza (INAF/Brera), P. D'Avanzo
(INAF/Brera), V. D'Elia (ASI/ASDC), A. Melandri (INAF/Brera), S.
Piranomonte (INAF/Roma), J.P.U. Fynbo (DARK/NBI), M. Cecconi (INAF/TNG),
G. Mainella (INAF/TNG), report on behalf of a larger collaboration:
We observed the afterglow of GRB 110422A (Mangano et al., GCN 11957;
Klunko et al., GCN 11958) with the Italian TNG located in La Palma. A
single 700 s spectroscopic exposure could be taken due to rising
humidity (see also Melandri et al., GCN 11963). Observations started on
2011 April 22.998 UT (8.25 hr after the GRB). The adopted grism was
LR-B, covering the wavelength range 3600-8200 AA.
We detect a clear absorption feature at 4290 AA. Interpreting this as
the (unresolved) CIV doublet yields a redshift of z = 1.77. At the same
redshift we find a few other lines which we interpret as due to Si IV
and Fe II. We thus propose z = 1.77 to be the redshift of GRB 110422A.