GCN Circular 19233

C. Delvaux (MPE Garching), D. A. Kann (TLS Tautenburg), F. Knust, and J. 
Greiner (both MPE Garching) report on behalf of the GROND team:

We observed the field of GRB 160325A (Swift trigger 680436; Sonbas et 
al., GCN #19222, Fermi GBM detection, Roberts, GCN #19924, Fermi LAT 
detection, Axelsson et al., GCN #19227) simultaneously in g'r'i'z'JHK 
with GROND (Greiner et al. 2008, PASP 120, 405) mounted at the 2.2 m MPG 
telescope at ESO La Silla Observatory (Chile).

Observations started at 23:29 UT on 25/03/2016, 16.5 hrs after the GRB 
trigger. They were performed at an average seeing of 1.7" and at an 
average airmass of 2.3.

We do not detect the source reported by Fugazza et Melandri (GCN #19223) 
down to the following magnitudes (in AB system):

g > 22.4 mag,
r > 22.5 mag,
i > 22.3 mag,
z > 22.4 mag,
J > 20.3 mag,
H > 19.8 mag, and
K > 18.5 mag.

Given upper limits are calibrated against GROND zeropoints as well as 
2MASS field stars and are not corrected for the expected Galactic 
foreground extinction corresponding to a reddening of E_(B-V)=0.1 mag in 
the direction of the burst (Schlafly & Finkbeiner 2011).