V. Sudilovsky, M. Tanga,
and J. Greiner (all MPE Garching) report on behalf of the GROND team:
We observed the field of GRB 131011A (Kasliwal et al., GCN #15324)
simultaneously in g'r'i'z'JHKs with GROND (Greiner et al. 2008, PASP 120,
405) mounted at the 2.2 m MPG telescope at La Silla Observatory
Observations started at 03:30 UT on 13 October 2013.
They were performed at an average seeing of 1.3" and at and
average airmass of 1.2. We find the afterglow candidate reported by Kasliwal et al.
Based on the first 1500 sec g'r'i'z' and 1200 sec JHK exposure,
we estimate preliminary magnitudes (all in AB) of
g' = 21.9 � 0.1 mag
r' = 21.7 � 0.1 mag,
i' = 21.5 � 0.1 mag,
z' = 21.3 � 0.1 mag,
J = 21.1 � 0.1 mag,
H = 20.5 � 0.2 mag,
K = 20.2 � 0.4 mag,
Magnitudes are calibrated against nearby SDSS (griz) and 2MASS (JHK) stars, and
are not corrected for the Galactic foreground extinction corresponding to
a reddening of E_(B-V)= 0.02 mag in the direction of the burst
(Schlegel et al. 1998).