TITLE: GCN CIRCULAR NUMBER: 10156 SUBJECT: GRB 091109B: VLT afterglow confirmation DATE: 09/11/10 10:00:29 GMT FROM: Daniele Malesani at Dark Cosmology Centre, Niels Bohr Inst D. Malesani (DARK/NBI), A. de Ugarte Postigo (INAF/OABr), A. J. Levan (Univ. Warwick), N. R. Tanvir (Univ. Leicester), J. Hjorth (DARK/NBI), P. D'Avanzo (INAF/Brera), report on behalf of a larger collaboration: Following the observations of GRB 091109B (Oates et al., GCN 10148) with the VLT reported by Levan et al. (GCN 10154), we obtained a further epoch of R-band imaging with mean time Nov 10.33 UT (10.22 hr after the burst), using the same instrument and configuration. Source "A" by Levan et al. (GCN 10154) is still detected, and decayed by 1.0+-0.3 mag during this time interval, implying a decay index of alpha = 1.7+-0.5. We hence conclude that the source is indeed the afterglow of GRB 091109B. We acknowledge excellent support from the ESO staff at Paranal, in particular Alain Smette and Paul Lynam.