GCN Circular 22544
T. Schweyer (MPE), and D. A. Kann (HETH/IAA-CSIC) report: We observed the field of GRB 180325A (Swift trigger 817564; E. Troja et al., GCN #22532) 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 02:53 UTC on March 25, 1.0 hours after the GRB trigger. They were performed at an average seeing of 1".5 and at an average airmass of 1.7. We clearly detect the NIR/optical transient of GRB 180325A within the enhanced XRT position (J. P. Osborne et al., GCN #22539), in agreement with the optical transient detected by UVOT (E. Troja et al., GCN #22532). Based on 7 minutes of exposure centered around 03:30 UTC, we measure the following magnitudes (all in AB system). g' = 20.45 +/- 0.03 mag r' = 19.57 +/- 0.02 mag i' = 19.18 +/- 0.02 mag z' = 18.30 +/- 0.02 mag J = 17.42 +/- 0.02 mag H = 16.85 +/- 0.02 mag K = 16.34 +/ 0.03 mag Given magnitudes are calibrated against SDSS in g'r'i'z' and 2MASS field stars in JHK, and are not corrected for the Galactic foreground extinction corresponding to a reddening of E_(B-V)= 0.015 in the direction of the burst (Schlafly & Finkbeiner 2011). We acknowledge the excellent support from the TiO and the current observer at the 2.2m in La Silla, Angela Hempel and Victor Marian.