GCN Circular 16229
Subject
GRB 140508A: NOT photometry and spectroscopy
Date
2014-05-09T02:30:41Z (10 years ago)
From
Daniele Malesani at Dark Cosmology Centre, Niels Bohr Inst <malesani@dark-cosmology.dk>
D. Malesani, D. Xu (DARK/NBI), P. D'Avanzo (INAF/OAB), E. Palazzi
(INAF/IASF Bologna), D. Perna (Obs. Paris) report on behalf of a larger
collaboration:
We observed the optical afterglow candidate of GRB 140508A (Yu &
Goldstein GCN 16224; Hurley et al., GCN 16225; Singer et al., GCN 16226)
with the Nordic Optical Telescope (NOT) equipped with ALFOSC. The
observation consisted of a 1800 s spectrum covering the wavelength range
between 3200 and 9100 AA, carried out at a mean time of 20.63 hr after
the GRB.
The afterglow is detected in the acquisition image (20.13 hr after the
GRB) with r = 19.07+-0.03 (AB) calibrated against SDSS stars. Compared
with the measurement by Singer et al. (GCN 16226), our measurement
yields a power-law decay slope alpha ~ 1, consistent with the value
reported by these authors.
We detect several absorption features which we intepret as due to Fe II
2600 and Mg II 2796, 2803 at a common redshift of z = 1.03. This can be
considered as a firm lower limit to the GRB redshift, and is consistent
with the constraint by Moskvitin et al. (GCN 16228).