TITLE:   GCN CIRCULAR
NUMBER:  20255
SUBJECT: GRB 161214A: GROND afterglow observations
DATE:    16/12/14 12:45:02 GMT
FROM:    Thomas Kruehler at MPE Garching  <kruehler@mpe.mpg.de>

T. Kruehler and J. Greiner (both MPE Garching) report on behalf
of the GROND team:

We observed the field of GRB 161214A (INTEGRAL trigger 7644;
Mereghetti et al., GCN #20251) simultaneously in g'r'i'z'JHK with
GROND (Greiner et al. 2008, PASP 120, 405) mounted at the 2.2m MPG
telescope at the ESO La Silla Observatory (Chile).

Observations started at 08:39 UT on 2016-12-14, 3.9 hr after the GRB
trigger. They were performed at an average seeing of 1".3, and at an
average airmass of 1.8.

Based on combined images with 9.7 min of total exposures in g'r'i'z'
and 10.0 min in JHK at a mid-time of 08:45 UT on 2016-12-14,
we derive the following preliminary magnitudes (all in AB system)
for the optical/NIR afterglow (Guidorzi et al., GCN 20252).

g' = 21.7 +- 0.2 mag
r' = 21.0 +- 0.1 mag
i' = 20.6 +- 0.1 mag
z' = 20.4 +- 0.1 mag
J = 20.2 +- 0.2 mag
H = 20.2 +- 0.3 mag

Given magnitudes are calibrated against SDSS/2MASS field stars and
are not corrected for the expected Galactic foreground extinction
corresponding to a reddening of E_(B-V) = 0.02 mag in the direction of
the burst (Schlafly & Finkbeiner 2011).