High precision meteor observations with the Canadian Automated Meteor Observatory -- Data reduction pipeline and application to meteoroid mechanical strength measurements

TL;DR

This paper details the upgraded data reduction pipeline of the Canadian Automated Meteor Observatory, analyzes meteor morphology's impact on measurement accuracy, and uses fragmentation observations to estimate meteoroid mechanical strengths.

Contribution

It introduces an improved hardware and data processing pipeline and applies it to measure meteoroid strengths through fragmentation analysis.

Findings

Meteor trajectory accuracy varies with morphology.

Measured meteoroid strengths range from 1-4 kPa.

Fragmentation type is independent of orbit.

Abstract

Context. The mirror tracking system of the Canadian Automated Meteor Observatory (CAMO) can track meteors in real time, providing an effective angular resolution of 1 arc second and a temporal resolution of 100 frames per second. Aims. We describe the upgraded hardware and give details of the data calibration and reduction pipeline. We investigate the influence of meteor morphology on radiant and velocity measurement precision, and use direct observations of meteoroid fragmentation to constrain their compressive strengths. Methods. On July 21, 2017, CAMO observed a ~4 second meteor on a JFC orbit. It had a shallow entry angle ~8 deg and 12 fragments were visible in the narrow-field video. The event was manually reduced and the exact moment of fragmentation was determined. The aerodynamic ram pressure at the moment of fragmentation was used as a proxy for compressive strength, and strengths of an additional 19 fragmenting meteoroids were measured in the same way. The uncertainty in the atmosphere mass density was estimated to be +/-25% using NAVGEM-HA data. Results. We find that meteor trajectory accuracy significantly depends on meteor morphology. The CAMO radiant and initial velocity precision for non-fragmenting meteors with short wakes is ~0.5' and 1 m/s, while that for meteors with fragments or long wakes is similar to non-tracking, moderate field of view optical systems (5', ~50 m/s). Measured compressive strengths of 20 fragmenting meteoroids (with less precise radiants due to their morphology) was in the range of 1-4 kPa, which is in excellent accord with Rosetta in-situ measurements of 67P. Fragmentation type and strength do not appear to be dependent on orbit. The mass index of the 12 fragments in the July 21 meteoroid was very high (s = 2.8), indicating possible progressive fragmentation.