GCN Circular 11809

T. Kruehler, J. Greiner, F. Schrey (all MPE Garching), and S. Klose (TLS
Tautenburg) report on behalf of the GROND team.

We observed the field of GRB 110318B (Swift trigger 449549; Margutti et
al., GCN #11800 simultaneously in g'r'i'z' with GROND (Greiner et al.
2008, PASP 120, 405) mounted at the 2.2 m MPI/ESO telescope at La Silla
Observatory (Chile).

Observation started at 07:40 UT, which is 16.2 h after the trigger, and
were obtained under clear skies with an airmass of around 1.1 and seeing
of 1"

In stacked images with a total integration time of 25 min, we do not
detect a source in the refined XRT error circle (Evans et al., GCN #11803)
to the following upper limits (AB system):

g' > 23.7
r' > 23.6
i' > 23.6
z' > 23.4

Given magnitudes are calibrated against GROND zeropoints and are not
corrected for the expected Galactic foreground extinction corresponding to
a reddening of E_(B-V)=0.46 mag in the direction of the burst (Schlegel et
al. 1998).

GROND is currently undergoing hardware maintenance, and hence no NIR data
are available for this burst.