GRB 191221B: Zadko observatory - Gingin optical observations

We imaged the field of GRB 191221B detected by Swift (trigger 945521, Laha et al. GCN 26534) with the Zadko robotic telescope (D=100cm) located at the Zadko observatory - Gingin, Australia. The observations started 19 hours after the GRB trigger. The elevation of the field was at 32 degrees above horizon and weather conditions were good. We performed 6 long exposures of 180s in Clear filter. We detected the candidate couterpart mentioned by Lipunov et al. (GCNC 26537) in each of the images. OT was R~17.6+/-0.2 at that time. Further analysis and observations are ongoing. Magnitudes were estimated with the nearby USNO-B1 stars and are not corrected for galactic dust extinction. This message may be cited.