TITLE:   GCN CIRCULAR
NUMBER:  16836
SUBJECT: GRB 140919A: GROND afterglow candidate
DATE:    14/09/20 03:46:13 GMT
FROM:    Sebastian Schmidl at TLS Tautenburg  <schmidl@tls-tautenburg.de>

S. Schmidl (TLS Tautenburg), J. Bolmer and J. Greiner (both MPE Garching)
report on behalf of the GROND team:

We observed the field of GRB 140919A (Swift trigger 613160; Gropp et al.,
GCN #16831) simultaneously in g'r'i'z'JHK with GROND (Greiner et al. 2008,
PASP 120, 405) mounted at the 2.2m MPG telescope at ESO La Silla
Observatory (Chile).

Observations started at 23:29 UT on 2014-09-19, 8.2 hrs after the GRB
trigger. They were performed at an average seeing of 1.7" and at an
average airmass of 2.1.

We detect a source inside the enhanced 1.5" Swift-XRT error cicle, at

RA  (J2000.0) =  14:46:08.96
DEC (J2000.0) = -32:10:34.6

with an uncertainty of 0.5" in each coordinate.

Based on total exposures of 7.7 minutes in g'r'i'z'and 24.0 minutes in
JHK, at a midtime of 9.2 hrs after the burst, we measure the following
preliminary magnitudes and upper limits (AB magnitude system):

g' = 19.8 +/- 0.1,
r' = 19.5 +/- 0.1,
i' = 19.4 +/- 0.1,
z' = 19.3 +/- 0.1,
J  = 18.9 +/- 0.1,
H  = 19.0 +/- 0.2, and
K  > 18.9.

At present we cannot decide if the source is fading.

Given magnitudes 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) = 0.09 mag
in the direction of the burst (Schlegel et al. 1998).