The Brightness of Starlink Mini Satellites During Orbit-Raising

TL;DR

This study analyzes the brightness mitigation of Starlink V2 Mini satellites during orbit-raising, showing significant reduction in brightness at lower altitudes and discussing implications for astronomy and public perception.

Contribution

It provides empirical evidence of brightness mitigation effectiveness for Starlink Mini satellites during orbit-raising and discusses their impact on astronomy and public awareness.

Findings

Brightness mitigation reduces satellite brightness by 93%.

Lower altitude satellites are less disruptive to astronomical observations.

Orbit-raising satellites attract public and pilot attention as UAPs.

Abstract

Observations of Starlink V2 Mini satellites during orbit-raising suggest that SpaceX applies brightness mitigation when they reach a height of 357 km. The mean apparent magnitudes for objects below that height threshold is 2.68 while the mean for those above is 6.46. When magnitudes are adjusted to a uniform distance of 1000 km the means are 4.58 and 7.52, respectively. The difference of 2.94 between distance-adjusted magnitudes above and below threshold implies that mitigation is 93% effective in reducing the brightness of orbit-raising spacecraft. Orbit-raising Mini spacecraft have a smaller impact on astronomical observations than higher altitude on-station spacecraft because they are relatively few in number. They also spend less time traversing the sky and spend longer in the Earth's shadow. These low-altitude objects will be more out-of-focus in large telescopes such as the LSST which reduces their impact, too. However, they attract considerable public attention and airline pilots have reported them as Unidentified Aerial Phenomena.