Distance-Independent Atmospheric Refraction Correction for Accurate Retrieval of Fireball Trajectories

Abstract

Accurate determination of fireball direction is essential for retrieving trajectories and velocities. Errors in these measurements have significant implications, affecting the calculated pre-impact orbit, influencing mass estimates, and impacting the accuracy of dark flight simulations, where applicable. Here we implement a new atmospheric refraction correction technique that addresses a significant aspect previously overlooked in the field of meteor science. Traditional refraction correction techniques, originally designed for objects positioned at infinite distances, tend to overcompensate when applied to objects within the Earth's atmosphere. To rectify this issue, our study introduces the concept of the atmospheric refraction delta z correction technique, involving the artificial elevation of the observer site height above sea level. We utilize analytically derived formulas for the delta z correction in conjunction with commonly used refraction models, validating these results against a numerical solution that traces light rays through the atmosphere. This ray-tracing model is applied to finely meshed atmospheric layers, yielding precise correction values. We evaluate multiple sources of error in order to quantify the achievable accuracy of the proposed method. Our approach (1) enables the determination of fireball positions with improved astrometric accuracy, (2) removes the explicit dependence on the fireball distance from the observer or its height above Earth's surface within the limits imposed by realistic atmospheric variability, and (3) simplifies meteor data processing by providing a robust framework for analyzing low-elevation fireball observations, for which atmospheric refraction is significant and is automatically corrected by the method. As a result of this work, we provide open, publicly accessible software for calculating the delta z correction.