[vsnet-grb-info 14133] GRB 131105A: VLT/X-shooter optical afterglow candidate

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  15447
SUBJECT: GRB 131105A: VLT/X-shooter optical afterglow candidate
DATE:    13/11/05 04:20:01 GMT
FROM:    Dong Xu at DARK/NBI  <dong.dark at gmail.com>

D. Xu (DARK/NBI), D. Malesani (DARK/NBI), N. R. Tanvir (U. Leicester),
T. Kruehler (ESO), report on behalf of a larger collaboration:

We observed the field of GRB 131105A (Cummings et al., GCN 15446) with
the acquisition camera of the X-shooter spectrograph at the VLT. The
observation was taken around 03:24 UT on November 5, that is 1.3 hr
after the GRB. Inside the current XRT error circle (2.0" radius; see
http://www.swift.ac.uk/xrt_positions/), we detect a single source at
coordinates (J2000):

RA = 04:43:52.27
Dec = -62:59:43.7

with an uncertainty of <0.5". Its magnitude is R = 22.4 +- 0.1,
compared to three nearby bright USNO stars.

At the moment we cannot conclude whether this source is variable or
associated to the GRB, but we propose it as a candidate counterpart.

We acknowledge excellent support from the ESO staff in Paranal, in
particular Dimitri Gadotti and Roger Wesson.