P. Afonso (MPE Garching), S. Klose (TLS Tautenburg), and J. Greiner (MPE
Garching), report on behalf of the GROND team:
GROND (Greiner et al. 2008, PASP 120, 405), the 7-channel imager mounted
at the 2.2m ESO/MPI telescope on La Silla, started follow-up observations
of the Swift/Fermi burst GRB 100522A (Troja et al. 2010, GCN 10784;
McBreen 2010, GCN 10790) on May 23 at 09:18 UT (about 29.5 hrs after the
burst), and continued for about 1 hour.
Within the enhanced XRT 1.5 arcsec error circle reported by Osborne et al.
(GCN 10787) we do not find any afterglow candidate. Based on 50 min of
total exposures in g'r'i'z' and 40 min in JHK, preliminary measured upper
limits are (in the AB system, 3 sigma):
g' > 24.8,
r' > 24.4,
i' > 23.6,
z' > 23.3,
J > 21.7,
H > 20.9,
K > 20.6,
using GROND zeropoints and the 2MASS catalog.