Any viable hypothesis for the VASCO transients must explain seven independent observational facts:
1. They have PSFs similar to stars. With the 1.4 m telescope optics, this means the sources must be hundreds of km away to avoid blurring (i.e., outside the atmosphere) during 45–50 min star-tracking exposures.
2. They are not present in images taken ~30 minutes earlier or later.
3. They sometimes appear and disappear in groups.
4. Some are aligned.
5. They correlate in time with nuclear tests.
6. They correlate in time with historical UFO reports.
7. They show a statistically significant deficit inside Earth’s shadow — they literally vanish there.
No natural or instrumental explanation proposed so far accounts for all seven properties at once.
Many experts offer explanations that account for one of the seven points — but are falsified when tested against the others.
Sean Kirkpatrick’s Mogul balloon hypothesis fails already at the first point. Brief flashes also get quickly diluted by the 50-minute exposure.
Plate defects won’t correlate with nuclear tests, historical UFO reports, or vanish in Earth’s geometric shadow at 42 000 km altitude.
Each alignment is statistically evaluated against randomness. The heavily contrived alternatives suggested by some experts, e.g. in Scientific American, were already falsified (or falsifiable) by the data. At present, the only hypothesis consistent with the full set of observations is that of artificial objects in high-altitude orbits, pre-Sputnik. And I believe a significant fraction (~1/3rd) of these transients are such.