Systematic non-compliance of satellite megaconstellations with IAU brightness limits
Abstract
Satellite megaconstellations in low Earth orbit interfere with ground-based optical astronomy, but the scale of that interference has been hard to measure. Here we report an uncued photometric survey from a mid-northern latitude site in late 2024 which recorded some 25,000 tracks of 5,118 individual satellites to a limiting visual magnitude of +9.0. The observed population is systematically brighter than the altitude-adjusted limit of order seventh magnitude recommended by the International Astronomical Union Centre for the Protection of the Dark and Quiet Sky from Satellite Constellation Interference (IAU CPS). Starlink satellites exceeded that limit on roughly a quarter of all geometrically possible passes, rocket bodies on about a fifth, and the emerging Guowang/Hulianwang constellation on more than half. OneWeb was the most compliant major operator (exceeding the IAU CPS limit on only about one in twenty possible passes), which shows that effective brightness mitigation is achievable with current technology. Satellite visibility is concentrated into the two hours after sunset and before sunrise and into limited regions of the sky. From the measured plane-of-sky satellite flux we predict that of order one in three 30 s twilight exposures at the Vera C. Rubin Observatory will carry a satellite trail.
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BibTeX
@misc{rayworth2026systematic,
title = {{Systematic non-compliance of satellite megaconstellations with IAU brightness limits}},
author = {Jack Rayworth and Denis Vida and Pauline Barmby and Peter G. Brown and Sarah Gallagher and Michael J. Mazur and David L. Clark and Maximilian Vovk and Stanimir Metchev and Lauchie Scott},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.10834},
eprint = {2610.10834},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.10834},
}
RIS
TY - UNPB
TI - Systematic non-compliance of satellite megaconstellations with IAU brightness limits
AU - Jack Rayworth
AU - Denis Vida
AU - Pauline Barmby
AU - Peter G. Brown
AU - Sarah Gallagher
AU - Michael J. Mazur
AU - David L. Clark
AU - Maximilian Vovk
AU - Stanimir Metchev
AU - Lauchie Scott
PY - 2026
DA - 2026/10/07
PB - arXiv
DO - 10.48550/arxiv.2610.10834
UR - https://arxiv.org/abs/2610.10834
AB - Satellite megaconstellations in low Earth orbit interfere with ground-based optical astronomy, but the scale of that interference has been hard to measure. Here we report an uncued photometric survey from a mid-northern latitude site in late 2024 which recorded some 25,000 tracks of 5,118 individual satellites to a limiting visual magnitude of +9.0. The observed population is systematically brighter than the altitude-adjusted limit of order seventh magnitude recommended by the International Astronomical Union Centre for the Protection of the Dark and Quiet Sky from Satellite Constellation Interference (IAU CPS). Starlink satellites exceeded that limit on roughly a quarter of all geometrically possible passes, rocket bodies on about a fifth, and the emerging Guowang/Hulianwang constellation on more than half. OneWeb was the most compliant major operator (exceeding the IAU CPS limit on only about one in twenty possible passes), which shows that effective brightness mitigation is achievable with current technology. Satellite visibility is concentrated into the two hours after sunset and before sunrise and into limited regions of the sky. From the measured plane-of-sky satellite flux we predict that of order one in three 30 s twilight exposures at the Vera C. Rubin Observatory will carry a satellite trail.
ER -