GCN Circular 23655

X.-Y.Li, Y.-D. Hu, I. Carrasco, E. Fernandez-Garcia and A. J. 
Castro-Tirado (IAA-CSIC), D. Hiriart and W. H. Lee (UNAM), S. Jeong and 
I. H. Park (SKKU) and M. D. Caballero-Garcia (ASU-CAS, CZ) on behalf of 
a larger collaboration, report:

The 60cm BOOTES-5/JGT robotic telescope at Observatorio Astronomico 
Nacional in San Pedro Martir (Mexico) followed-up GRB 190109B 
(Sbarufatti et al., GCNC 23648) starting at 13:30 UT (~1.6 hr after 
trigger). Within the enhanced Swift/XRT position (Beardmore et al., GCNC 
23652), no optical afterglow is found down to 20.4 mag in the r-band on 
the co-added image, in agreement with the UVOT upper limit (Sbarufatti 
et al., GCNC 23648).

We thank the staff at Observatorio Astronomico Nacional in San Pedro 
Martir for its excellent support.