[vsnet-grb-info 14935] GRB 140508A: NOT photometry and spectroscopy

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  16229
SUBJECT: GRB 140508A: NOT photometry and spectroscopy
DATE:    14/05/09 02:30:41 GMT
FROM:    Daniele Malesani at Dark Cosmology Centre, Niels Bohr Inst  <malesani at 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).