TITLE: GCN CIRCULAR NUMBER: 9519 SUBJECT: Optical observations of GRB 090618 DATE: 09/06/18 12:37:13 GMT FROM: Alberto Carraminana at AzTEC A. Carraminana (INAOE), C. Alvarez Ochoa (UNACh) and G. Miramon (OAGH-INAOE) report: We clearly detected the optical counterpart of GRB 090618 (GCN 9512) with the 2.1m telescope of the Observatorio Astrofisico Guillermo Haro at Cananea, Sonora, Mexico. Observations started at 08:43 UT, 14 minutes after the BAT trigger and continued until dawn. Observations were made under non photometric conditions. We measured a lineal faddening of the burst compared to a reference star of amplitude 0.5 magnitudes between t=870s to 1600s. A non calibrated graph is available at http://www.inaoep.mx/~alberto/gamma/grb090618_lc.jpg Spectroscopic data were also obtained and are under analysis.