Satellite Optical Brightness

Abstract The apparent brightness of satellites is calculated as a function satellite position seen by ground-based observer in darkness. Both direct illumination the Sun well indirect due to reflection from Earth are included. reflecting properties components and must first be estimated (the Bidirectional Reflectance Distribution Function, or BRDF). can found directly using lab measurements accurately inferred multiple observations at various solar angles. Integrating over all scattering surfaces leads angular pattern flux satellite. Finally, an given location position. We develop improved model for light Earth’s surface aircraft data. find that indirectly reflected contributes significant increases brightness. This effect particularly strong during civil twilight. validate our approach comparing calculations selected Starlink show improvement on previous models. Similar methodology predicting has already informed mitigation strategies next-generation satellites. Measurements variety angles widens effectiveness virtually demonstrate empirical which functions chassis panels fit observed data performs very well. work finds application design operations, planning observatory acquisition analysis.