[vsnet-grb-info 17760] GRB 160314A: GROND optical/NIR observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  19200
SUBJECT: GRB 160314A: GROND optical/NIR observations
DATE:    16/03/16 15:55:55 GMT
FROM:    Jan Bolmer at MPE/Garching  <jan at bolmer.de>

T. Schweyer, J. Bolmer and J. Greiner (all MPE Garching) report on
behalf of the GROND team:

We observed the field of GRB 160314A (Swift trigger 679120; D'Elia et
al., GCN #19182) 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 23:53 UT on 2016-03-15, 36.3h after the GRB
trigger. They were performed at an average seeing of 1.1" and at an
average airmass of 1.5.

We clearly detect the source reported by Malesani et al. (GCN #19191)
and Butler et al. (GCN #19196).

Based on 90 min of exposure in g'r'i'z' and 96 min in JHK, at a mid-time
of 00:44 UT on 2016-03-16, we derive the following preliminary magnitudes
and upper limits (all in the AB system):

g' = 23.3 +/- 0.1 mag,
r' = 23.1 +/- 0.1 mag,
i' = 22.6 +/- 0.1 mag,
z' = 22.5 +/- 0.1 mag,
J > 22.2 mag,
H > 21.8 mag, and
K > 20.4 mag.

Given detections and upper limits are calibrated against SDSS
as well as 2MASS field stars. No correction for the expected Galactic
foreground extinction corresponding to a reddening of E_(B-V)=0.07 mag in
the direction of the burst (Schlafly & Finkbeiner 2011) has been applied.

Our r'-band magnitude, combined with that of RATIR (Butler et al., GCN #19196)
suggests a very slow fading, possibly indicating that we are close to the
brightness of the host galaxy (Malesani et al. GCN #19191, D'Elia et al., GCN #19192).