Observational Methods
Satellite fleets keep overshooting the sky's brightness limit
An uncued survey logs 25,000 tracks and finds large operator-to-operator differences, with one in three Rubin twilight exposures predicted to carry a trail.
Briefed October 9, 2026 · Aliens in the Clouds
Preprint · Satellite Foreground Measured
Jack Rayworth and colleagues used an uncued photometric survey from a mid-northern site to record roughly 25,000 tracks from 5,118 individual satellites in late 2024. After adjusting the International Astronomical Union's recommended brightness limit for altitude, Starlink exceeded it on about one quarter of geometrically possible passes, rocket bodies on about one fifth, and the emerging Guowang/Hulianwang constellation on more than half.
OneWeb exceeded the limit on only about one pass in twenty, evidence that current technology can substantially reduce brightness. The team finds visibility concentrated near twilight and predicts that roughly one in three thirty-second Vera C. Rubin Observatory twilight exposures will contain a satellite trail. The manuscript is still in revision, so those rates should be tested against other sites, seasons, and constellation configurations.
Why it matters
Satellite trails and glints contaminate transient searches and can become raw material for false mystery claims. Measured rates help observatories design mitigation and help the public recognize an increasingly common foreground.
What the source establishes
Preprint submitted October 7 and under revision with Nature Astronomy. The exceedance rates come from a large 2024 survey; the Rubin fraction is a prediction derived from measured sky flux, not a completed Rubin census.
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