TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3400 SUBJECT: GRB050509c: REM NIR and Optical observations DATE: 05/05/10 02:59:38 GMT FROM: Angelo Antonelli at Obs. Astro. di Roma P. D'Avanzo, S. Piranomonte, L.A. Antonelli, S. Covino, F.M. Zerbi, G. Chincarini, M. Rodono', G. Tosti, P. Conconi, G. Cutispoto, E. Molinari, L. Nicastro, E. Palazzi, V. Testa, F. Vitali, E. Meurs, P. Goldoni, on behalf of the REM/ROSS Team report: "We imaged the central part of the field of GRB050509 with the robotic 60-cm REM telescope located at La Silla, Chile. REM is equipped with the REMIR near infrared camera (10x10 sq arcmin FoV, JHK filters) and the ROSS optical spectrograph/imager (10x10 sq arcmin FoV, VRI filters and AMICI prism). Observations of GRB 050509 were performed in fully automated mode simultaneously in the near infrared and in the optical starting approximately 56 seconds after the burst (32 seconds after the reception of the burst alert). Then, 2 hrs after the burst, REM performed automatically a further observation of the refined position of GRB 050509 few seconds after the new trigger delivered by the HETE Team. A preliminary analysis of both the H and R band images does not reveal any new object down to the 2MASS and DSS limits respectively." This message may be cited.