TITLE: GCN CIRCULAR NUMBER: 15158 SUBJECT: GRB 130831B: GROND upper limits DATE: 13/09/01 15:08:32 GMT FROM: Vladimir Sudilovsky at MPE V. Sudilovsky, M. Tanga, and J. Greiner (all MPE Garching) report on behalf of the GROND team: We observed the field of GRB 130831B (Swift trigger 568855; Malesani et al. 2013, GCN #15141) simultaneously in g'r'i'z'JHK with GROND (Greiner et al. 2008, PASP 120, 405) mounted at the 2.2 m MPG/ESO telescope at La Silla Observatory (Chile). Observations started at 23:22 UT on 31 Aug. 2013, 10 hours after the GRB trigger. They were performed at an average seeing of 2.2" and at an average airmass of 2.2. Based on five co-added images with individual exposures of 6 min in g'r'i'z' and 4 min exposure in JHK, we do not detect a source within the 3.6 arcsec Swift-XRT error circle reported by Malesani et al. (2013; GCN #15141) down to (all in the AB system) g' > 23.4, r' > 23.2, i' > 22.6, z' > 22.3, J > 20.8, H > 20.2, and K > 19.6 The given limits are derived based on calibrating the images against GROND zeropoints and 2MASS field stars and are not corrected for the Galactic foreground extinction corresponding to a reddening of E_(B-V)= 0.08 in the direction of the burst (Schlegel et al. 1998).