Starlink Satellite Brightness -- Characterized From 100,000 Visible Light Magnitudes

TL;DR

This study analyzes over 100,000 visible light measurements of Starlink satellites to understand their brightness, phase functions, and variability, improving prediction models for satellite visibility and planning.

Contribution

It introduces a detailed brightness function tailored to Starlink satellite shapes and characterizes brightness flares, enhancing predictive accuracy over previous models.

Findings

Strong forward scattering of sunlight by satellites

Brightness varies over months and years

Flares last a few seconds with measurable rates

Abstract

Magnitudes for the VisorSat and Original-design types were analyzed separately and by time. Mean values are compared with those from other large-scale photometric studies, and some signficant differences are noted. The illumination phase functions for Starlink satellites indicate strong forward scattering of sunlight. They are also time-dependent on a scale of months and years. These phase functions improve the predictability of satellite magnitudes. A Starlink Brightness Function tailored to the satellite shape also improves magnitude predictions. Brightness flares lasting a few seconds are characterized and the mean rate of magnitude variation during a pass is determined. Observation planning tools, including graphs and statistics of predicted magnitudes, are discussed and illustrated.