GCN Circular 23209

C. Perez del Pulgar, A. Castellon, I. Carrasco (Univ. de Malaga), Y.-D. 
Hu, E. Fernandez-Garcia, J. C. Tello, A. Ayala, A. J. Castro-Tirado 
(IAA-CSIC), and M. Jelinek (ASU-CAS), on behalf of a larger 
collaboration, report:

The 60cm BOOTES-2/TELMA robotic telescope at IHSM La Mayora (UMA-CSIC) 
in Algarrobo Costa (Spain) automatically responded in 56s (and 116s 
after the GRB onset) to the Swift trigger of GRB 180904A (D'Ai et al. 
GCNC 23194). The first image (11s exposure, unfiltered) was obtained at 
21:30:28 UT. At the position of the enhanced Swift X-ray afterglow 
(Osborne et al. GCNC 23196), no optical afterglow is detected down to 19 
mag at a mid time of 6 minutes post burst. This is consistent with the 
limits reported by Malesani et al. (GCNC 23195), Izzo et al. (GCNC 
23197), Moskvitin et al. (GCNC 23198, Guidorzi et al. (GCNC 23199), 
Butler et al. (GCNC 23204), Siegel et al. (GCNC 23205), Volnova et al. 
(GCNC 23206).