TITLE: GCN CIRCULAR NUMBER: 17386 SUBJECT: GRB 150203A: GROND Upper limits DATE: 15/02/03 08:54:48 GMT FROM: Karla Varela at MPE C. Delvaux, K. Varela and J. Greiner (all MPE Garching) report on behalf of the GROND team: We observed the field of GRB 150203A (SWIFT-629578; Ukwatta et al., GCN #17377) 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 on February 3rd, 2015, at 04:20 UT, 11 minutes after the GRB trigger. They were performed at an average seeing of 1.2" and at an average airmass of 2.1. The distance from the moon was only 28 deg. We do not detect a source inside the 2.1 arcsec error circle reported by Ukwatta et al. (GCN #17377). Based on a total exposure of 0.83 hours in g'r'i'z' and 0.80 hours in JHK, at a midtime of 0.7 hour after the burst, we measure the following preliminary upper limits (AB magnitudes system): g' > 23.5 mag, r' > 23.9 mag, i' > 24.0 mag, z' > 24.1 mag, J > 21.5 mag, H > 20.9 mag, and K > 18.6 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) = 0.88 mag in the direction of the burst (Schlegel et al. 1998).