Eclipses by Artificial Satellites to Measure the Angular Sizes of Stars
Abstract
Direct measurements of the angular sizes of stars (other than our Sun) are inherently limited by telescopes' optical diffraction limit. The spatial diffraction limit can be overcome by using time-domain information when stars are `eclipsed' by anything moving in the foreground: artificial satellites or the Moon (known as `lunar occultation imaging'). Here we analyse the angular resolution achievable by high-speed photon counting devices, when stars are eclipsed for several microseconds by one of the thousands of satellites now in low or mid-Earth orbit. We also build a full Bayesian statistical treatment for analysing simulated observations. We show that eclipses by the moon and satellites deliver <2 milliarcsecond resolution for ∼104 stars every year, with the diameters of ∼101 − 102 stars constrained to better than $0.5$ milliarcseconds. The application of satellites requires an ultra-fast, photon-resolving detector, capable of continuous readout with inter-frame delay controlled within ≲ 1 μs. Such a fast rate can easily be handled by the SPINA instrument, which has demonstrated $8$ ns inter-frame delay, and potentially by the Cherenkov Telescope Array.
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BibTeX
@misc{fung2026eclipses,
title = {{Eclipses by Artificial Satellites to Measure the Angular Sizes of Stars}},
author = {Leo W. H. Fung and Albert Wai Kit Lau and Richard Massey and George F. Smoot},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2608.11161},
eprint = {2608.11161},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2608.11161},
note = {CC BY-NC-SA 4.0},
}
RIS
TY - UNPB
TI - Eclipses by Artificial Satellites to Measure the Angular Sizes of Stars
AU - Leo W. H. Fung
AU - Albert Wai Kit Lau
AU - Richard Massey
AU - George F. Smoot
PY - 2026
DA - 2026/10/07
PB - arXiv
DO - 10.48550/arxiv.2608.11161
UR - https://arxiv.org/abs/2608.11161
AB - Direct measurements of the angular sizes of stars (other than our Sun) are inherently limited by telescopes' optical diffraction limit. The spatial diffraction limit can be overcome by using time-domain information when stars are `eclipsed' by anything moving in the foreground: artificial satellites or the Moon (known as `lunar occultation imaging'). Here we analyse the angular resolution achievable by high-speed photon counting devices, when stars are eclipsed for several microseconds by one of the thousands of satellites now in low or mid-Earth orbit. We also build a full Bayesian statistical treatment for analysing simulated observations. We show that eclipses by the moon and satellites deliver <2 milliarcsecond resolution for ∼10^4 stars every year, with the diameters of ∼10^1 − 10^2 stars constrained to better than $0.5$ milliarcseconds. The application of satellites requires an ultra-fast, photon-resolving detector, capable of continuous readout with inter-frame delay controlled within ≲ 1 μs. Such a fast rate can easily be handled by the SPINA instrument, which has demonstrated $8$ ns inter-frame delay, and potentially by the Cherenkov Telescope Array.
ER -