[vsnet-grb-info 17869] GRB 160412A: GROND upper limits

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  19314
SUBJECT: GRB 160412A: GROND upper limits
DATE:    16/04/14 09:54:48 GMT
FROM:    Jan Bolmer at MPE/Garching  <jan at bolmer.de>

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

We observed the field of GRB 160412A (Swift trigger 682522; Gibson et
al., GCN #19298) 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 23:11 UT on 2016-04-12, 18.8 h after the GRB
trigger. They were performed at an average seeing of 2.5“ and at an
average airmass of 2.3.

We detect no source within or close to the Swift-XRT error circle
reported by Goad et al. (GCN #19299).

Based on 36 min of exposure in g'r'i'z' and 37 min in JHK, at a mid-time
of 023:35 UT, we derive the following preliminary upper
limits (in AB system):

g' > 23.5 mag,
r' > 23.6 mag,
i' > 22.9 mag,
z' > 22.7 mag,
J > 20.2 mag,
H > 29.6 mag, and
K_s > 19.7 mag.

Given upper limits are calibrated against GROND zeropoints (g'r'i'z')
as well as 2MASS field stars (JHK_s). No correction for the expected Galactic
foreground extinction corresponding to a reddening of E_(B-V)=0.03 mag in
the direction of the burst (Schlafly & Finkbeiner 2011) has been applied.