Detection of GRBs and OTs by All-Sky Optical and SID Monitors
Figure 5
Ondrejov Observatory EN network photographic plate, central part (converted to negative). The EN network uses fish-eye lenses F-Distagon 3.5/30, and the images are recorded on planfilms 90 120 mm; sky diamater is 80 mm and typical exposure time 3 hours resulting in limiting magnitude 11.
