GCN Circular 23159

E. Fernandez-Garcia, Y.-D. Hu, J. C. Tello, A. Ayala and A. J. 
Castro-Tirado (IAA-CSIC), I. Carrasco and C. Perez del Pulgar (Univ. de 
Malaga), M. D.
Caballero-Garcia and M. Jelinek (ASU-CAS, CZ), R. Cunniffe (Inst. of 
Physics, 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 in 59s (and 193s after the GRB onset) 
to the Swift trigger of GRB 180821A (Tohuvavohu et al., GCNC 23158). The 
first images (clear filter) were obtained starting at 16:43:47 UT. At 
the position of the Swift/XR X-ray position, no optical afterglow is 
detected down to 19 mag on a 100s co-added image at 16:44:45 
(mid-exposure), in agreement with the non-detection by Swift/UVOT. 
Further analysis is ongoing.

We thank the staff at NIWA for its excellent support.