TITLE: GCN CIRCULAR NUMBER: 9420 SUBJECT: GRB 090520: GROND upper limits DATE: 09/05/22 23:53:35 GMT FROM: Andrea Rossi at TLS Tautenburg A. Rossi (Tautenburg), T. Kruehler and J. Greiner (both MPE Garching) report on behalf of the GROND team: GROND (Greiner et al. 2008, PASP 120, 405) at the 2.2m ESO/MPI telescope at La Silla Observatory (Chile) started follow-up observations of GRB 090520 (Cummings et al. 2009, GCN #9417) on May 21, at 09:35 UTC (~32 h after the burst). In addition, a second epoch of imaging was obtained, which started on May 22, 09:37 UTC. Image subtraction does not reveal any variable source between the two epochs. The first epoch thus yields the following upper limits: g > 23.8 r > 24.0 i > 23.4 z > 23.2 J > 21.8 H > 21.4 K > 20.8 obtained using the GROND zeropoints and 2MASS field stars as reference.