[vsnet-grb-info 17175] GRB 151029A VLT/X-shooter redshift

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  18524
SUBJECT: GRB 151029A VLT/X-shooter redshift
DATE:    15/10/29 10:48:11 GMT
FROM:    Nial Tanvir at U.Leicester  <nrt3 at star.le.ac.uk>

Nial R. Tanvir (Univ. Leicester), Thomas Kruehler (MPE), Daniele
Malesani (DARK/NBI), Dong Xu (NAOC/CAS), Antonio de Ugarte Postigo
(IAA-CSIC),  Giovanna Pugliese (API/UvA) report on behalf of
a larger collaboration:

We observed the optical counterpart of GRB 151029A (Ukwatta et al., GCN
18522; Knust et al., GCN 18523) using the ESO Very Large Telescope UT2
equipped with the X-shooter spectrograph. Observations started on Oct
29.369 UT (1.02 hr after the GRB), that is at the end of the Chilean
night, and were extended over twilight.

The optical counterpart (Ukwatta et al., GCN 18522; Knust et al., GCN
18523) is clearly detected in our grz acquisition images.

We detect a faint continuum throughout the spectral range of
our observations, from about 3300A to 18000A, indicating
an upper limit to the redshift of z~2.  We also detect several
weak absorption features that would be consistent with being
MgII (2796/2804) and FeII (2344/2587/2600) lines at z=1.423,
which we therefore report as the likely redshift for this GRB.

We acknowledge expert support from the ESO observing staff, in
particular Thomas Rivinius and Marcela Espinoza.