[vsnet-grb-info 17828] GRB 160410A: GROND optical detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  19272
SUBJECT: GRB 160410A: GROND optical detection
DATE:    16/04/10 06:34:19 GMT
FROM:    Robert Yates at MPE/Swift  <robyates at mpe.mpg.de>

R Yates (MPE Garching) , T Kruehler (MPE Garching), J Greiner (MPE
Garching) report on behalf of the GROND team:

We observed the field of GRB 160410A (Swift trigger 682269; Gibson et al.,
GCN #19271) 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 ESO La Silla
Observatory (Chile).

Observations started at 05:42 UT on 10-04-2016, 32mins after the GRB
trigger. They were performed at an average seeing of 1.8" and at an
average airmass of 2.7.

We found a single point source within the 0.7" Swift-UVOT error circle
reported by Gibson et al. (GCN #19271) at

RA (J2000.0) = 10h 02m 44.37s

DEC (J2000.0) = +03d 28' 42.4"

with an uncertainty of 0.5" in each coordinate.

Based on the first 4 min of total exposures in g'r'i'z' and JHK, we
estimate preliminary magnitudes (all in AB system) of

g' = 20.6 +/- 0.1 mag,
r' = 20.5 +/- 0.1 mag,
i' = 20.7 +/- 0.1 mag,
z' = 20.5 +/- 0.2 mag,
J > 20.0 mag,
H > 19.6 mag, and
K > 18.0 mag.

Given magnitudes are calibrated against SDSS/2MASS 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)=0.0180 mag
in the direction of the burst (Schlafly & Finkbeiner 2011).