TITLE: GCN CIRCULAR NUMBER: 19027 SUBJECT: GRB 160220A: GROND Optical/NIR Upper Limits DATE: 16/02/20 08:06:33 GMT FROM: Philip Wiseman at MPE/Swift P. Wiseman, F. Knust, J. Greiner (all MPE Garching) report on behalf of the GROND team: We observed the field of GRB 160220A (Swift trigger 674670; Lien et al., GCN #19023) 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 05:46 UT on 2016-02-20, 4.5 hrs after the GRB trigger. They were performed at an average seeing of 1.5" and at an average airmass of 1.6. We do not find any single point source within the 1.9" Enhanced Swift-XRT error circle reported by Evans et al. (GCN #19025). Based on 36.00 min of total exposures in g'r'i'z' and 30.00 min in JHK, at a mid-time of 06:49 UT, we estimate preliminary upper limiting magnitudes (AB system) of g' > 23.4 mag, r' > 23.9 mag, i' > 23.6 mag, z' > 23.3 mag, J > 21.6 mag, H > 20.9 mag, and K > 18.0 mag. Given limits 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)=0.12 mag in the direction of the burst (Schlafly & Finkbeiner 2011).