Ultra-high-energy cosmic ray detection using next-generation prototypes of the Fluorescence detector Array of Single-pixel Telescopes (FAST) in both hemispheres

Unraveling the origin and nature of ultra-high-energy cosmic rays (UHECRs) stands as an essential inquiry in astroparticle physics. Motivated by new observational capabilities, the Fluorescence detector Array of Single-pixel Telescopes (FAST) emerges as a promising next-generation, ground-based UHECR observatory. FAST will employ a cost-effective array of cutting-edge fluorescence telescopes, each equipped with four 200 mm diameter photomultiplier tubes positioned near the focal plane of a segmented 1.6 m diameter mirror. Currently, there are three prototypes in operation at the Telescope Array experiment and one at the Pierre Auger Observatory. Together they enable remote observation of UHECRs in both hemispheres using the same technology. Here, we present recent developments regarding a new generation of prototypes, including hardware/software updates and installation plans, together with recent progress in signal detection and data reconstruction.