GCN Circular 12418
Subject
GRB 111005A: VLT optical observations
Date
2011-10-06T10:01:01Z (13 years ago)
From
Daniele Malesani at Dark Cosmology Centre, Niels Bohr Inst <malesani@dark-cosmology.dk>
D. Malesani (DARK/NBI), A.J. Levan (Univ. Warwick), N.R. Tanvir, K.
Wiersema (Univ. Leicester), J. Hjorth, J. P. U. Fynbo (DARK/NBI), report
on behalf of a larger collaboration.
We observed the surroundings of the galaxy ESO 580- G 049, which is
overlapping the BAT error circle of GRB 111005A (Saxton et al., GCN
12413; Barthelmy et al., GCN 12415; Levan et al., GCN 12414).
Observations were carried out with the acquisition camera of the
X-shooter spectrograph mounted on the ESO VLT. Images were taken in the
z and I bands, and were carried out deep in twilight. We note that our
data only cover a small fraction of the BAT error circle. The time of
the observation is October 5, 23:40 UT (i.e., 15.6 hr after the GRB),
and the exposure time was 30 s in both z and I.
Our data reach somewhat deeper than the DSS survey; our limiting
magnitude is I ~ 20.5 (assuming I = 16.3 for the star at RA =
14:53:07.299, Dec = -19:43:43.63). No new sources can be recognized in
comparison to the DSS survey, in agreement with previous reports (Levan
et al., GCN 12416; Nardini et al., GCN 12417). A few objects (fainter
than the DSS limit) can be seen consistent with the galaxy disk,
although their association with the GRB cannot be ascertained at this stage.
We acknowledge the excellent support of the ESO staff at Paranal in
scheduling and executing such a challenging observation, in particular
Christophe Martayan and Maja Vuckovic.