TITLE: GCN CIRCULAR NUMBER: 24043 SUBJECT: GRB 190331B: BOOTES-3/YA optical observations DATE: 19/04/02 21:52:40 GMT FROM: Alberto Castro-Tirado at Inst.de Astro. de Andalucia Y.-D. Hu, X.-Y.Li, E. Fernandez-Garcia, A. Ayala, A. J. Castro-Tirado (IAA-CSIC), C. Perez del Pulgar, A. Castellon, I. Carrasco (Univ. de Malaga), and R. Querel (NIWA), on behalf of a larger collaboration, report: The 60cm BOOTES-3/YA robotic telescope at NIWA Lauder in Otago (New Zealand) responded to the Swift ground-detected burst GRB 190331B (Page et al. GCNC 24041) ~2.36 day after the burst. The first images (clear filter) were obtained starting on April 2, 12:39 UT. At the uncatalogued X-ray source position found by Swift/XRT, no optical afterglow is detected down to 20.3 mag on a 900s co-added image, in agreement with the non-detection by Swift/UVOT. We thank the staff at NIWA for its excellent support.