[vsnet-grb-info 11001] GRB 111005A: VLT optical observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  12418
SUBJECT: GRB 111005A: VLT optical observations
DATE:    11/10/06 10:01:01 GMT
FROM:    Daniele Malesani at Dark Cosmology Centre, Niels Bohr Inst  <malesani at 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.