Satellite trails in 1 in 6 VST images: how neural networks find them
In 2023 the VLT Survey Telescope on Cerro Paranal recorded 1,246,048 CCD frames with its OmegaCAM imager. A team led by Elisabeth Rachith at EPFL ran all of them through a deep-learning streak detector, and their June 2026 preprint reports 25,335 streaks from satellites, rocket bodies and debris, with at least one in 16.9% of exposures. In the months checked by hand, about a fifth of the confirmed streaks matched nothing in the public satellite catalogue. Below: how these networks work, what the VST numbers say, and why a stack of backyard subs mostly doesn’t need one. ...