Assessing Brightness Mitigations of Low-Earth Orbit Satellites

Hundreds of low-Earth orbit satellite constellations have been launched since mid-2019, and tens of thousands are planned in the coming years. The number and brightness of these satellite “constellations” have the potential to significantly harm ground-based optical astronomy. Various partial mitigation strategies have been proposed, which broadly include fewer satellites, lower orbits, darker satellites, improved satellite tracking, and algorithms to identify and mask or remove satellite trails from data products. These all require an accurate characterization of the problem. To this end, we present recent optical observations of SpaceX Starlink satellites and report their stationary apparent magnitudes at zenith. We remark on the efficacy of various darkening mitigations and estimate the impact on Vera C. Rubin Observatory, one of the most heavily-impacted optical facilities due to its large primary mirror and wide field of view.