Photometry of fireballs using high frame rate cameras

Abstract Fast sampling photometry is a key observable for characterising fireballs, particularly their fragmentation episodes, which are strongly connected to the internal structure of the meteoroid and its physical properties. Accurate photometric measurements remain a challenge due to the large dynamic range required (upwards of 10 stellar magnitudes), driving operational complexity and cost. We have developed a system using an all-sky camera operating at up to 500 frames per second (FPS), featuring a novel implementation of detection localised auto-brightness control. The large data throughput is managed by custom software that performs transient detection, region-of-interest saving, and real-time photometry. We present results from two field deployments: the first validates the system’s photometric accuracy against conventional 30 FPS cameras, while the second demonstrates the successful implementation of detection localised auto-brightness control in capturing a bright, magnitude $-15$ fireball with minimal saturation. With the detection localised auto-brightness control, the system achieves an effective dynamic range between apparent magnitudes of approximately $-3$ to $-17$ , allowing it to capture light curves with minimal saturation for most fireballs, excluding rare superbolides. The resulting high-quality light curve enabled a successful semi-empirical fragmentation analysis verifying the system’s 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.