Precise off-specular angle during the 2022 Starlink 4-26 UAP event

Determine the precise off-specular (off-beam) angle between the specularly reflected ray from the nadir side of the Starlink version 1.5 satellite chassis and the line of sight to the observers during the 2022 airline-pilot observation of the Starlink 4-26 satellite train, using the reported brightness values, distance adjustments, and the Sun–satellite–observer geometry described in the paper.

Background

The paper analyzes extreme flares from Starlink satellites produced by specular reflection from the nadir side of the chassis, demonstrating a strong dependence of brightness on the off-specular angle and validating the observed brightness function against SpaceX’s bidirectional reflectance distribution function (BRDF) for Starlink version 1.5.

In a 2022 incident, airline pilots observed very bright objects later identified as the Starlink 4-26 satellite train. The authors adjust the reported magnitudes to a standard range, compare them to the BRDF, and infer small off-specular angles, but state that the exact off-beam angle cannot be precisely determined due to measurement precision, varying numbers of objects, changing geometry, potential differences in satellite attitude, and brightness contributions from other components.