TITLE: GCN CIRCULAR NUMBER: 24750 SUBJECT: GRB 190604B: BOOTES-3 early optical limits DATE: 19/06/05 05:52:15 GMT FROM: Alberto J. Castro-Tirado at IAA-CSIC Y.-D. Hu, X.-Y.Li, E. Fernandez-Garcia, A. Ayala and A. J. Castro-Tirado (IAA-CSIC), I. Carrasco and C. Perez del Pulgar (Univ. de Malaga), M. D. Caballero-Garcia (ASU-CAS, CZ) 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) automatically responded to the Swift GRB 190604B (Page et al. GCNC 24742) only 35 s after the burst). At the position of the Swift/XRT enhanced X-ray position (Evans et al. GCNC 24746), no optical afterglow is detected down to R = 15.5 (for the 1-s image gathered at 14:57:50 UT) or down to 19.8 mag (for the co-added 9x10s unfiltered images at mid-time 15:05:56 UT, i.e. 8.7 min after trigger). We thank the staff at NIWA for its excellent support.