TITLE: GCN CIRCULAR NUMBER: 23298 SUBJECT: GRB181002A: GOTO optical limits DATE: 18/10/03 13:34:51 GMT FROM: Danny Steeghs at U.of Warwick/GOTO K.Ulaczyk, D.Steeghs, J.Lyman (U. Warwick), G.Ramsay (Armagh O.), M.Dyer (U. Sheffield), B.Gompertz, A.Levan, R.Cutter (U. Warwick) K. Ackley, D.Galloway, E.Rol (Monash U.), V.Dhillon (U. Sheffield), P.O'Brien, R.Starling (U. Leicester), S.Poshyachinda (NARIT), D.Pollacco (U. Warwick), E.Thrane (Monash U.), E.Palle (IAC) report on behalf of the GOTO collaboration: In response to GRB 181002A (Gropp et al. GCN 23290), the Gravitational-wave Optical Transient Observer (GOTO) observed the field near the Swift BAT/XRT detection. Observations started at 2018-10-03T01:19:02 UT (13.9 hours after the burst) consisting of a set of 3x5x120s exposures in our wide L filter (400-700nm). We do not detect any optical source within the error circle of the enhanced XRT location (Beardmore et al. GCN 23292) with a 5-sigma limit of g=20.8, using PanSTARRS calibrators on the stacked image. We note that our limits are deeper than those reported in Lipunov et al. GCN 23293 and Emery et al. GCN 23297, albeit obtained 13.9 hours post-burst. GOTO is operated at the La Palma observing facilities of the University of Warwick on behalf of a consortium including the University of Warwick, Monash University, Armagh Observatory, the University of Leicester, the University of Sheffield, the National Astronomical Research Institute of Thailand (NARIT) and the Instituto de Astrofisica de Canarias (IAC) https://goto-observatory.org/