TITLE: GCN CIRCULAR NUMBER: 11120 SUBJECT: GRB 100816A: NOT optical observations DATE: 10/08/17 09:24:04 GMT FROM: Daniele Malesani at Dark Cosmology Centre, Niels Bohr Inst D. Malesani (DARK/NBI), D. Xu (Weizmann Inst.), J.P.U. Fynbo (DARK/NBI), P. Jakobsson (Univ. Iceland), L. Buchhave, T. Hansen (NBI), report on behalf of a larger collaboration: We observed the field of GRB 100816A (Oates et al., GCN 11102) with the NOT equipped with ALFOSC. Observations were carried out in the R band. The mid point of the observation is August 17.04 UT (24.3 hr after the GRB). We clearly detect both the optical afterglow (Oates et al., GCN 11102) and the putative host galaxy (Im et al., GCN 11108; Tanvir et al., GCN 11109). We find magnitudes of R = 23.0 +- 0.1 and R = 21.65 +- 0.05 for the two objects, respectively, assuming R=17.06 for the nearby USNO star 1165-0595190. We caution that accurate photometry will have to await for late-time templates to isolate the contribution of both objects. [GCN OPS NOTE(17aug10): Per author's request, TH was added to the author list.]