GCN Circular 22662
The field of GRB 180418A (Swift trigger 826428; D'Elia et al., GCN #22646) was observed 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 01:27 UT on 19th April, 18.7 hours after the GRB trigger. They were performed at an average seeing of 1.5" and at an average airmass of 1.7. A source is detected in the g'r'i' bands at a position consistent with the X-ray and optical afterglow (Zheng et al., GCN #22647; Goad et al., GCN #22650). The source is not clearly point-like, and it is therefore possible that some host galaxy light is contributing to the flux. Based on 22 min of exposure in g'r'i'z' and 20 min in JHK, the estimated AB magnitudes are: g' = 23.60 +/- 0.14 mag r' = 23.24 +/- 0.13 mag i' = 22.88 +/- 0.21 mag z' > 22.96 mag J > 21.16 mag H > 20.67 mag K > 18.82 mag Given magnitudes are calibrated against SDSS for g'r'i'z' and 2MASS field stars for JHK, and they are not corrected for the expected Galactic foreground extinction corresponding to a reddening of E(B-V)=0.01 mag in the direction of the burst (Schlafly & Finkbeiner 2011). I thank Sam Kim for his excellent support from La Silla.