Trigger system for the TA fluorescence detector

The Telescope Array (TA) is a hybrid detector system consisting of fluorescence detectors (FDs) and a surface detector (SD) array to study ultra high energy cosmic rays. In this paper, we describe the development and status of the trigger system for the TA FDs. The trigger system consists of three components, those are the Signal Digitizer and Finder (SDF) module, the Track Finder (TF) module and the Central Trigger Distributor (CTD) module. The SDF module recognizes the fluorescence signal, TF finds air shower tracks and CTD controls data acquisition. We also report the first engineering run carried out in 2007.