TITLE: GCN CIRCULAR NUMBER: 19349 SUBJECT: GRB 160425A: GROND observation DATE: 16/04/26 09:20:09 GMT FROM: Jochen Greiner at MPI J. Bodensteiner (MPE Garching), S. Schmidl (TLS Tautenburg), and J. Greiner (MPE Garching) report on behalf of the GROND team: We observed the field of GRB 160425A (Swift trigger 684098; Krimm et al. GCN Circ. 19343) 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 04:38 UT on April 26, 2016, 5.2 hrs after the GRB trigger. They were performed at an average seeing of 3.1" and at an average airmass of 1.2. We detect an optical source at the position reported by Krimm et al. (GCN 19343) and Lipunov et al. (GCN 19344). Based on total exposures of 24 minutes in g'r'i'z' and 20 minutes in JHK, at a midtime of 7.16 hrs after the burst, we measure the following preliminary magnitudes and upper limits (AB magnitude system): g' = 22.2 +/- 0.3 mag, r' = 21.1 +/- 0.2 mag, i' = 20.7 +/- 0.2 mag, z' = 20.5 +/- 0.1 mag, J = 19.7 +/- 0.2 mag, H = 19.4 +/- 0.3 mag, and K > 18.3 mag. The magnitudes and upper limits are calibrated against GROND zeropoints and 2MASS field stars and are not corrected for the Galactic foreground extinction corresponding to a reddening of E_(B-V)= 0.06 mag in the direction of the burst (Schlegel et al. 1998). Relative to the UVOT and MASTER reports, the source has faded, though we do not detect significant fading in our data so far (strongly mitigated by the bad conditions). We therefore cannot distinguish between afterglow or host flux.