TITLE: GCN CIRCULAR NUMBER: 13657 SUBJECT: GRB120816A: OPTIMA discovery of optical counterpart DATE: 12/08/16 21:39:46 GMT FROM: Arne Rau at MPE Arne Rau and Gottfried Kanbach (both MPE Garching) report on behalf of the OPTIMA-Burst Team: "We observed the location of GRB 120816A (Page et al. GCN #13654) with OPTIMA-Burst (Kanbach et al. 2008, Astrophys. and Sp. Sci. Lib. Vol. 351, 153) currently mounted at the 1.3m telescope at Skinakas Observatory, University of Crete. Observations started at 19:22:44 UT (249 sec after the burst) with unfiltered 20s exposures using the field-viewing CCD camera. Within the updated XRT error circle we find a fading source located at: RA(J2000) = 18:48:34.4 Dec(J2000) = -06:56:16 with an approximate uncertainty of 1" in both coordinates. We measure the following magnitudes: T0+ white -------------- 249s ~17.8 4844s >19.1 calibrated against the R=15.2mag reference star USNO-B1.0 0830-0537586."