GCN Circular 19042

P. Wiseman, J. Greiner (both MPE Garching) report on behalf of the GROND
team:

We observed the field of GRB 160220B (Swift trigger 674734; Cummings et
al., GCN #19029) 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  07:12 UT on 2016-02-21, ~20 hrs after the GRB
trigger. They were performed at an average seeing of 1.5" and at an
average airmass of 1.8.

We detect a single point source at the southern edge of the 1.5" enhanced
Swift-XRT error circle reported by Evans et al. (GCN #19033), at the
position RA, Dec (J2000) = 259.86531, -18.12433, which is equivalent to:

RA  =17h 19m 27.67s
Dec =-18d 07m 27.6s,

with an uncertainty of 0.3" in each coordinate.

Based on 72.00 min of total exposures at a mid-time of 07:54 UT, we
estimate a preliminary magnitude (AB system) of:

r' = 20.0 +/- 0.1

No statement about the variability of this source can be made at this time.

The given magnitude is calibrated against GROND zeropoints and is not
corrected for the expected Galactic foreground extinction corresponding to
a reddening of E_(B-V)=0.25 mag in the direction of the burst (Schlafly &
Finkbeiner 2011).