TITLE: GCN CIRCULAR NUMBER: 21024 SUBJECT: GRB 170419B: Zadko observatory - Gingin optical observations DATE: 17/04/20 14:19:03 GMT FROM: Alain Klotz at IRAP-CNRS-OMP A. Klotz, D. Turpin (IRAP-CNRS-OMP), D. Macpherson (UWA/ICRAR), D. Coward (UWA), M. Boer, (UNS-CNRS-OCA), Gendre B. (UVI - Etelman Obs.), A. Williams (PO-UWA), R. Martin (PO-UWA) report: We imaged the field of GRB 170419B detected by SWIFT (trigger 748947) with the Zadko robotic telescope (D=100cm) located at the observatory - Gingin, Australia. The observations started 13.3h after the GRB trigger. The elevation of the field decreased from 31 degrees above horizon and weather conditions were good. We co-added a series of exposures but we did not find any optical transcient in the BAT error box provided by Cholden-Brown et al. (GCNC 21016): t0+13.3h to t0+13.5h : Rlim = 19.2 Magnitudes were estimated with the nearby NOMAD1 stars and are not corrected for galactic dust extinction.