GCN Circular 9456
A. Rossi (Tautenburg), F. Olivares, and J. Greiner (both MPE Garching) report on behalf of the GROND team: We observed the field of GRB 090531 (Swift trigger 353627, Stamatikos et al., GCN #9454) simultaneously in g'r'i'z'JHK with GROND mounted at the 2.2m MPI/ESO telescope at La Silla Observatory (Chile). Observations started on 31 May 2009 at 01:47 UT, 2 minutes after the burst and continued until 03:29 UT. We do not find any new source within the BAT error circle. Image subtraction between the first and last images of each band does not reveal any variable source. The first image , consisting of 4.4 min exposure in g'r'i'z' and 4 min in JHK, yields the following upper limits (all AB): g' > 22.6 r' > 22.8 i' > 22.4 z' > 22.0 J > 21.5 H > 20.9 K > 20.2 which were obtained using the SDSS and 2MASS field stars as reference.