TITLE: GCN CIRCULAR NUMBER: 10396 SUBJECT: GRB 100206A: GROND upper limits DATE: 10/02/07 17:40:07 GMT FROM: Thomas Kruehler at MPE/MPI A. Nicuesa (Tautenburg Obs.), T. Kruehler (MPE), S. Klose (Tautenburg Obs.) and J. Greiner (MPE Garching) report on behalf of the GROND team: We observed the field of GRB 100206A (Swift trigger #411412; Krimm et al., GCN #10376) simultaneously in g'r'i'z'JHK with GROND (Greiner et al. 2008, PASP 120, 405) mounted at the 2.2 m MPI/ESO telescope at LaSilla Observatory (Chile). Observations started on 7 February 2010 at 00:31 UT, 11 hours after the GRB trigger, and were performed at high airmass and poor seeing conditions. In stacked images with a total integration time of 40 minutes in JHK and 50 minutes in g'r'i'z' we do not detect the object reported by Levan et al. (GCN #10386) and Berger et al. (GCN #10395) down to the following limits, all in the AB system: g' > 23.2, r' > 23.4, i' > 22.4, z' > 22.2, J > 21.2 , H > 20.7 and K > 20.0 These upper limits have been obtained using the GROND zeropoints and 2MASS field stars as reference. The nearby object (Miller et al., GCN#10377, Bhattacharya et al., GCN#10380, Guziy et al., GCN#10384, Leloudas et al., GCN#10387, Cenko et al., GCN# 10389, Morgan et al., GCN#10390, Mao et al. #10392) is detected in all seven bands.