Photometry of Fireballs using High Frame Rate Cameras

Abstract

Fast sampling photometry is essential for characterising fireballs and their fragmentation episodes which link to the meteoroid internal structure. Accurate measurements remain challenging due to the large required dynamic range of up to 10 stellar magnitudes driving up operational complexity and cost. We developed an all-sky camera system operating at up to 500 frames per second featuring a novel Detection Localised Auto-brightness Control. Custom software manages high data throughput via transient detection and region-of-interest saving with real-time photometry. Two field deployments validate photometric accuracy against conventional 30 frames per second cameras and demonstrate the successful capture of a bright magnitude -15 fireball with minimal saturation. The system achieves an effective dynamic range between apparent magnitudes -3 and -17 capturing minimally saturated light curves for most fireballs. A successful semi-empirical fragmentation analysis verifies its ability to provide data for detailed physical modelling. The primary application for this validated system will be as a core component of the Global Fireball Observatory's next-generation instrumentation. The intention is to deploy it in a hybrid observatory, operating alongside a dedicated high-resolution astrometric camera. This configuration will allow the network to simultaneously capture precise trajectory data for orbit and fall-line calculations and acquire complete, unsaturated high dynamic range light curves at high temporal resolution for detailed physical analysis, combining the strengths of both systems.