A. de Ugarte Postigo (IAA-CSIC, DARK/NBI), D. Xu (DARK/NBI),
J. Gorosabel (EHU-UPV, IAA-CSIC), D. Malesani (DARK/NBI),
B. Milvang-Jensen (DARK/NBI), M.I. Andersen (DARK/NBI),
P. Jakobsson (U. Iceland), J.P.U. Fynbo (DARK/NBI), and
A. Somero (Tuorla Obs.) report on behalf of a larger collaboration:
Following the photometry reported in GCN 15921, we have performed spectroscopy
of GRB 140304A (Gorbovskoy et al. GCN 15914, Evans et al. GCN 15915) with the
Nordic Optical Telescope (NOT) equipped with ALFOSC. The observation began at
21:20 UT (7.97 hr after the burst) and consisted of a single 1500 s exposure
covering the range between 3200 and 9100 A.
We detect continuum emission with a deep absorption consistent with a
DLA at a redshift of 5.28+/-0.02, as well as emission down to ~5800 A, which
is consistent with the Ly-limit at a similar redshift. Despite the lack of metal
features identified in our spectrum, a redshift of z=5.39 as reported by
Jeong et al. (GCN 15922) is inconsistent with our data.