TITLE: GCN CIRCULAR NUMBER: 8045 SUBJECT: GRB 080727B: GROND redshift limit DATE: 08/07/28 21:21:10 GMT FROM: Jochen Greiner at MPI T. Kruehler, J. Greiner, F. Schrey, C. Clemens, A. Yoldas (all MPE Garching), A. Kupcu Yoldas (ESO) and G. Szokoly (Eoetvoes Univ., Budapest) report on behalf of the GROND team: Since telescope pointing constraints did not allow a prompt observation of GRB 080727B (Swift trigger 318101, Immler et al. 2008, GCN #8022), GROND (Greiner et al. 2008, PASP 120, 405), mounted at the 2.2m ESO/MPI telescope at La Silla Observatory (Chile), started observations in g'r'i'z'JHK only on Jul 27, 23:08 UT, nearly 15 hrs after the burst. Under mediocre conditions a total of 90 min effective exposure in g'r'i'z' and 76 min in JHK was collected. Correcting for foreground extinction of A_V = 6.15 (Schlegel et al. 1998), we measure the following AB magnitudes/limits: g'>17.7, r'>19.7, i'>19.9, z'=19.8+-0.1, J=19.45+-0.15, H=19.2+-0.1, K=19.0+-0.15. The corresponding SED is well fit by a single power law with slope 0.85, with no evidence of additional (intrinsic) extinction, and with the i'-limit being consistent with that power law. Our SED power law has an extinction-corrected R-H=1.0. The best fit Hyper-z redshift to our data gives z=5.5-6.5, with a firm upper limit of 6.7. Given the non-constraining upper limits at i' and bluer, no lower limit can be placed. If the color R-H = 3.24 mag from the combination of KAIT (Li et al. 2008, GCN #8024) and REM data (D'Avanzo et al. 2008, GCN #8037) is correct, then the redshift of GRB 080727B would be larger than 5.8.