GCN Circular 11383

T. Kruehler, F. Olivares, M. Nardini and J. Greiner (all MPE Garching)
report on behalf of the GROND team:

GROND (Greiner et al. 2008, PASP 120, 405), mounted at the 2.2m MPG/ESO
telescope at La Silla Observatory (Chile), started observations of the
field of GRB 101024A (de Pasquale et al., GCN #11370) in g'r'i'z'JHK at
07:42 UT on 2010-10-26, 43.7 h after the burst. We detect the optical
afterglow (de Pasquale et al., GCNs #11370, 11375, Hentunen et al., GCN
#11373, Laas-Bourez et al., GCNs #11380, 11382) marginally in the r' and
i' bands.

Preliminary AB magnitudes and upper limits at a midtime of 08:14 UT on
2010-10-26 in stacked images with 50 min of total integration time in each
g'r'i'z' and 40 min in JHK are:

g' > 24.1
r' = 24.5 +- 0.3
i' = 23.8 +- 0.2
z' > 23.7
J > 21.8
H > 21.3
K > 20.5

These magnitudes have been derived by calibrating the images against the
GROND zeropoints and 2MASS field stars and are not corrected for the
expected foreground reddening of E(B-V)=0.088 in the direction of the burst
(Schlegel et al. 1998).