[vsnet-grb-info 13935] GRB 130925A: VLT/UVES observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  15249
SUBJECT: GRB 130925A: VLT/UVES observations
DATE:    13/09/25 10:45:42 GMT
FROM:    Paul Vreeswijk at Weizmann Inst of Science  <paul.vreeswijk at weizmann.ac.il>

P. M. Vreeswijk (Weizmann), D. Malesani, J. P. U. Fynbo (DARK/NBI),
A. De Cia (Weizmann) and C. Ledoux (ESO) report:

GRB 130925A (Lien et al., GCN 15246; Suzuki et al., GCN 15248) was
observed with UVES at the ESO-VLT, in Rapid Response Mode, starting at
around 5 UT (50 minutes after the Swift trigger). A series of spectra
were taken of the brightest object near the XRT error circle. We
caution that the small field of view of the UVES acquisition camera
and the lack of nearby bright stars does not allow us to identify this
object unambiguously as the optical counterpart discovered by
Sudilovsky et al. (GCN 15247).

Preliminary analysis of the automatically reduced spectra reveals the
presence of a very faint continuum in the red part and a pair of
emission lines at 8845 A and 8873 A. These lines can be identified
with Halpha and [NII] 6585 at a redshift of z=0.347.

We are grateful for the excellent support at Paranal provided by
Jonathan Smoker and Patricia Guajardo, and we thank D. A. Kann and the
GROND team for showing us a finding chart of the afterglow field.