Trigger Sensitivity of the FADC Instrumented HiRes Fly's Eye

A flash analog-to-digital (FADC) based data acquisition system has been designed for the HiRes Fly's Eye detector. A prototype system has been constructed and installed on a single mirror at Dugway, Utah. The trigger sensitivity of the system has been measured using laser shots fired from up to 20 km away. We present the preliminary results of this measurement.