Aug 12, 2025 05:36 PM
(This post was last modified: Aug 12, 2025 05:39 PM by Yazata.)
I debated whether to post this here, or in the astronomy forum.
First, there's this from the Monthly Notices of the Royal Astronomical Society in 2022:
https://academic.oup.com/mnras/article/5...ogin=false
"Transients can be defined as astrophysical phenomena whose duration is significantly lower than the typical time-scale of the stellar and galactic evolution (from seconds to years in contrast to millions or billions of years). Supernovae, novae, gamma-ray bursts, etc., are some examples of transient events.
While most of the modern surveys have developed robust and well-tested facilities to discover transients... the same level of attention is not paid to vanishing events, that is, objects detected in old surveys but that are not identified in more recent ones. In this context, vanishing refers both to known types of objects faded below the detection limits (e.g. large-amplitude variables) as well to unknown physical phenomena non predicted before."
The reason it's here and not in astronomy is this 2025 preprint by the same authors: Aligned Multiple-Transient Events in the First Palomar Sky Survey?
https://www.researchgate.net/publication...bXlCdz0%3D
in which the authors believe that they may have discovered indications apparently consistent with highly reflective objects orbiting the Earth in geosynchronous orbit, years before Sputnik.
Here's the Abstract (highlighting by me):
"Old, digitized astronomical images taken before the human spacefaring age offer a rare glimpse of the sky before the era of artificial satellites. In this paper, we present the first optical searches for artificial objects with high specular reflections near the Earth. We follow the method proposed in Villarroel et al. (2022) and use a transient sample drawn from (Solano et al. 2022). We use images from the First Palomar Sky Survey to search for multiple (within a plate exposure) transients that, in addition to being point-like, are aligned along a narrow band. We provide a shortlist of the most promising candidates, including one with \sim3.9\sigma statistical significance. As in previous cases (Villarroel et al. 2021, Solano et al. 2023), no known astrophysical or instrumental explanations fully account for these events. We explore remaining possibilities, including fast reflections from highly reflective objects in geosynchronous orbit, or emissions from artificial sources high above Earth's atmosphere. Notably, the \sim3.9\sigma candidate coincides in time with the Washington D.C. 1952 UFO flyover, and another (a \sim2.0\sigma candidate) falls within a day of the peak of the 1954 UFO wave (Figuet 1980). We also find a highly significant (\sim22\sigma) deficit of transients from Solano et al. 2022 within Earth's shadow, supporting the interpretation that sunlight reflection plays a key role in producing these events. This study should be viewed as an initial exploration into the potential of archival photographic surveys to reveal transient phenomena, and we hope it motivates more systematic searches across historical datasets."
First, there's this from the Monthly Notices of the Royal Astronomical Society in 2022:
https://academic.oup.com/mnras/article/5...ogin=false
"Transients can be defined as astrophysical phenomena whose duration is significantly lower than the typical time-scale of the stellar and galactic evolution (from seconds to years in contrast to millions or billions of years). Supernovae, novae, gamma-ray bursts, etc., are some examples of transient events.
While most of the modern surveys have developed robust and well-tested facilities to discover transients... the same level of attention is not paid to vanishing events, that is, objects detected in old surveys but that are not identified in more recent ones. In this context, vanishing refers both to known types of objects faded below the detection limits (e.g. large-amplitude variables) as well to unknown physical phenomena non predicted before."
The reason it's here and not in astronomy is this 2025 preprint by the same authors: Aligned Multiple-Transient Events in the First Palomar Sky Survey?
https://www.researchgate.net/publication...bXlCdz0%3D
in which the authors believe that they may have discovered indications apparently consistent with highly reflective objects orbiting the Earth in geosynchronous orbit, years before Sputnik.
Here's the Abstract (highlighting by me):
"Old, digitized astronomical images taken before the human spacefaring age offer a rare glimpse of the sky before the era of artificial satellites. In this paper, we present the first optical searches for artificial objects with high specular reflections near the Earth. We follow the method proposed in Villarroel et al. (2022) and use a transient sample drawn from (Solano et al. 2022). We use images from the First Palomar Sky Survey to search for multiple (within a plate exposure) transients that, in addition to being point-like, are aligned along a narrow band. We provide a shortlist of the most promising candidates, including one with \sim3.9\sigma statistical significance. As in previous cases (Villarroel et al. 2021, Solano et al. 2023), no known astrophysical or instrumental explanations fully account for these events. We explore remaining possibilities, including fast reflections from highly reflective objects in geosynchronous orbit, or emissions from artificial sources high above Earth's atmosphere. Notably, the \sim3.9\sigma candidate coincides in time with the Washington D.C. 1952 UFO flyover, and another (a \sim2.0\sigma candidate) falls within a day of the peak of the 1954 UFO wave (Figuet 1980). We also find a highly significant (\sim22\sigma) deficit of transients from Solano et al. 2022 within Earth's shadow, supporting the interpretation that sunlight reflection plays a key role in producing these events. This study should be viewed as an initial exploration into the potential of archival photographic surveys to reveal transient phenomena, and we hope it motivates more systematic searches across historical datasets."
