GCN Circular 22701
P. Schady (MPE, Garching) reports: We observed the field of GRB 180510B (Swift trigger 831816; Tohuvavohu et al., GCN #22696) 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 23:14 UT on 10th May, 3.0 hours after the GRB trigger. They were performed at an average seeing of 1.3" and at an average airmass of 1.8. A single point source is present within the 1.5" Swift-XRT error circle reported by Beardmore et al. (GCN #22698) at RA (J2000.0) = 05:11:52.66 DEC (J2000.0) = -62:19:26.4 with an uncertainty of 0.2" in each coordinate. Based on 6.6 min of total exposures in g'r'i'z' and 6 min in JHK, the estimated AB magnitudes are g' = 20.5 +/- 0.1 mag r' = 20.0 +/- 0.1 mag i' = 19.8 +/- 0.1 mag z' = 19.6 +/- 0.1 mag J = 18.8 +/- 0.1 mag H = 18.5 +/- 0.1 mag K = 18.0 +/- 0.1 mag Given magnitudes 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)=0.02 in the direction of the burst (Schlafly & Finkbeiner 2011). I would like to thank Markus Rabus for his excellent support from La Silla.