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Photometry of Fireballs using High Frame Rate Cameras

Dale Giancono, Hadrien Devillepoix, Robert Howie, Denis Vida, David Rollinson

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.

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.
Paper Structure (11 sections, 2 equations, 17 figures, 4 tables)

This paper contains 11 sections, 2 equations, 17 figures, 4 tables.

Table of Contents

  1. Introduction
  2. Instrument Description
  3. Hardware
  4. Fireball Detection and Processing
  5. Detection Localised Auto-brightness Control
  6. System Characterisation and Performance
  7. Photometric Validation using the Moon as a Standard
  8. Photometric Validation and Comparison with a 30 FPS System
  9. Application of High-Cadence Data to Fragmentation Analysis
  10. Discussion
  11. Conclusion

Figures (17)

  • Figure 1: Locations of the Perenjori and Forrest Airport prototypes, as well as the FRIPON station used for photometric verification. The trajectories of 20240506 and DN250711_02 are also shown.
  • Figure 2: Left: Prototype installation near Perenjori, Western Australia. Right: Allied Vision Alvium U-052 USB machine vision camera connected to a weatherproofed Fujinon FE185C046HA lens assembly.
  • Figure 3: Top: a 10 second calibration image which includes a bright Moon and light reflections from nearby objects. Bottom: Automatically generated bright object mask as well as the user mask which masks areas within the image to prevent false positive detections from occurring
  • Figure 4: Pipeline for triggering detection
  • Figure 5: Top left: Unprocessed image of a fireball. Top right: Thresholded image. Bottom left: Contoured image of which both hot pixels and the fireball have been identified. Bottom right: Aperture selected around the fireball.
  • ...and 12 more figures