Development of the calibration device using UAV mounted UV-LED light source for the fluorescence detector

The Telescope Array (TA) experiment located in Utah, USA aims at observing ultra-high-energy cosmic rays (UHECRs) with energies greater than 10¹⁸ eV. TA utilizes two types of detectors, the fluorescent detectors (FDs) in three stations that measure fluorescent photons emitted by air molecules along a cosmic ray shower, and the surface detectors (SDs) that measure shower particles at the ground. We have developed a standard UV-LED light source mounted on an unmanned aerial vehicle (UAV), so-called the Opt-copter, for the calibration of the fluorescence detectors (FDs) of the Telescope Array experiment. The positioning accuracy of the UAV controlled by GPS is ∼ 10 cm, which enables an accurate calibration of the pointing directions of the FD phototubes. We report the hardware details of the device and the status of data analysis. (authors)