GCN Circular 10314

R. Filgas, F. Olivares, J. Greiner, T. Kruehler (all MPE Garching)
and S. Klose (Tautenburg Observatory) report on behalf of the GROND team:

We observed the field of GRB 100103A (INTEGRAL trigger #5970; Gotz et al.,
GCN #10307) 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 on January 4, 2010 at
00:48 UT, 7.1 hours after the GRB trigger. They were performed at
variable seeing of 2-3" and at an average airmass of 1.4.

No source is found within the 1.7" XRT error circle (Page et al., GCN #10312).
Comparison to the Digital Sky Survey and 2MASS also reveals no new sources
within a 10 arcsec surrounding. Co-added images of 24.6 min of integration time
in g'r'i'z' and 20 min in JHK, centered at 01:29 UT yield the following 
specific upper limits (AB system):

g' > 24.9
r' > 24.2
i' > 23.6
z' > 23.8
J > 21.2 
H > 20.6 
K > 19.2 

calibrated against USNO and 2MASS field stars. No correction for the Galactic
foreground extinction was made, which correspond to a reddening of 
E(B-V)=0.29 mag in the direction of the burst (Schlegel et al. 1998).