TITLE: GCN CIRCULAR NUMBER: 10991 SUBJECT: GRB 100725A: GROND upper limits DATE: 10/07/26 02:05:22 GMT FROM: Felipe Olivares Estay at MPE F. Olivares E. (MPE Garching), S. Klose (Tautenburg), and J. Greiner (MPE Garching) report on behalf of the GROND team: GROND (Greiner et al. 2008, PASP 120, 405), the 7-channel imager mounted at the 2.2m ESO/MPI telescope on La Silla, started follow-up observations of GRB 100725A (Markwardt et al. 2010, GCN 10979) on July 25 at 23:05 UT (about 16 hrs after the trigger). With a total integration time of 24.4 min in the optical and 20 min in the nIR, we do not detect any source within the 1.8-arcsec XRT error circle (Evans et al. 2010, GCN 10985) down to the following upper limits (AB system): g' > 22.8 r' > 23.3 i' > 23.1 z' > 22.9 J  > 21.7 H  > 21.1 K  > 20.4, The given limits are calibrated againt GROND zeropoints and 2MASS field stars and are not corrected for the Galactic foreground extinction corresponding to a reddening of E(B-V)= 0.052 in the direction of the burst (Schlegel et al. 1998).