Satellite Streak Brightness Variation with Orbit Height

Abstract

We study the apparent optical brightness of satellite streaks in ground-based observatory cameras as the orbit height is varied. This is done via simulations. Several factors are in play: the range to the satellite, satellite size and geometry, the diameter of the telescope aperture, and the angular velocity of the satellite image as it streaks across the camera's focal plane. For a large telescope aperture, a satellite in a lower orbit becomes out-of-focus in a camera focused at infinity. In the case of Rubin Observatory's LSSTCam, we find that these factors nearly cancel as a large satellite is moved from an orbit at 550 km down to 350 km.