Studying the Optical Emission of Lightning at the Telescope Array Detector.

Terrestrial gamma-ray flashes (TGFs) are bursts of gamma rays occurring in the Earth's atmosphere during thunderstorms. The Telescope Array Surface Detector (TASD), the largest ultra-high-energy cosmic ray detector in the Northern Hemisphere, has been leading groundbreaking observations of the TGF phenomenon since 2017. The TASD consists of 507 scintillator detectors arranged on a 1.2 km square grid in the southwestern desert of Utah. In addition to the TASD, a suite of lightning detectors was installed to study lightning in detail, including a Lightning Mapping Array, an INTF, a fast antenna, a high-speed video camera, a slitless spectroscopic system, and a photometric array. This work presents an analysis of data recorded by the photometric array during 2023/2024, in conjunction with other lightning detection instruments. In my presentation, I will discuss the optical emissions in the ultraviolet (337 nm) and infrared (777 nm) ranges recorded by the photometers and analyzed for various types of lightning flashes. These observations provide a better understanding of lightning initiation and propagation, which will help in developing conclusive support for the model responsible for TGF initiation.