TITLE:   GCN CIRCULAR
NUMBER:  8958
SUBJECT: GRB 090306B: GROND Upper Limits
DATE:    09/03/09 13:29:06 GMT
FROM:    Christian Clemens at MPE  <cclemens@mpe.mpg.de>

A. C. Updike (Clemson University), C. Clemens, J. Greiner and P. Afonso (MPE 
Garching) report on behalf of the GROND team:

We observed the field of GRB 090306B (BATSS, Copete et al., GCN #8944) 
simultaneously in g'r'i'z'JHK with GROND (Greiner et al. 2008, PASP 120, 405) 
mounted at the 2.2 m ESO/MPI telescope at La Silla Observatory (Chile).

Observations started at 04:34 UT on March 8th, about 29.5 hours after the GRB 
trigger, and lasted 45 min.

We do not detect a source within the Swift-XRT error circle reported by Evans 
(GCN #8947) down to (all in AB system)

g' > 23.2,
r' > 23.6,
i' > 23.3,
z' > 23.0,
J > 21.7,
H > 21.0 and
K > 20.1.

The given limits are derived based on calibrating the images against GROND 
zeropoints and 2MASS field stars and are not corrected for the Galactic 
foreground extinction corresponding to a reddening of E_(B-V)= 0.11 in the 
direction of the burst (Schlegel et al. 1998).