TITLE:   GCN CIRCULAR
NUMBER:  23702
SUBJECT: GRB 190114C: GROND detection of the afterglow
DATE:    19/01/15 01:58:25 GMT
FROM:    Jan Bolmer at MPE/Garching  <jan@bolmer.de>

J. Bolmer (MPE, Garching) and P. Schady (Univ. of Bath) report:

We observed the field of GRB 190114C (Swift trigger 883832; Gropp et al., GCN #23688) 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 the ESO
La Silla Observatory (Chile).

Observations started at 00:48 UT on 15th January, around 3.8 hours after the GRB trigger. They were performed
at an average seeing of 1.0" and at an average airmass of 1.0. 

We found a source consistent with the one reported by Selsing et al., GCN #23695.

Based on the first 5.8 min of exposure in g'r'i'z', and 8.0 min in JHK, we report the
following preliminary AB magnitudes:  

g =  19.00 +/- 0.09 mag
r = 18.17 +/-  0.03  mag
i =  17.66 +/- 0.05 mag
z = 17.15 +/-  0.04 mag
J = 16.76 +/- 0.05 mag
H = 16.30 +/- 0.05 mag
K = 16.08 +/- 0.07 mag

The above magnitudes are calibrated against PanSTARRS and 2MASS and are not corrected for the expected
Galactic foreground extinction corresponding to a reddening of E_(B-V)=0.01 in the direction
of the burst (Schlafly & Finkbeiner 2011).