TITLE: GCN CIRCULAR NUMBER: 23833 SUBJECT: GRB 190202A: GOTO optical observations DATE: 19/02/02 12:48:07 GMT FROM: Danny Steeghs at U.of Warwick/GOTO D.Steeghs (U.Warwick), Y.-L.Mong (Monash U.), G.Ramsay (Armagh O.), M.Dyer (U. Sheffield), J.Lyman, K.Ulaczyk (U. Warwick), A.Obradovic, K. Ackley, D.K. Galloway, E.Rol (Monash U.), K. Wiersema, B.Gompertz, A.Levan, R.Cutter (U. Warwick), V.Dhillon (U. Sheffield), P.O'Brien, R.Starling (U. Leicester), S.Poshyachindav(NARIT), D.Pollacco (U. Warwick), E.Thrane (Monash U.), E.Palle (IAC) report on behalf of the GOTO collaboration: In response to Swift BAT trigger 887217 (GRB190202A; Lien et al. GCN 23830), the Gravitational-wave Optical Transient Observer (GOTO) observed the survey field covering the Swift BAT/XRT positions. Due to adverse weather, observations started at 2019-02-02T03:51:41 (2.2 hours post burst) consisting of a set of 5x120s exposures in our wide L filter (400-700nm). We detect the optical counterpart coincident with the revised XRT position reported in Evans et al. (GCN 23832) at a S/N of 18. Preliminary pipeline photometry based off a PS1 zeropoint provides g=19.1 +/- 0.2, with the uncertainty including a systematic error component due to the calibration uncertainty. This has not been corrected for galactic extinction. 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/)