A preprint posted April 2026 by Kevin Cann (arXiv:2604.16470) directly tests and rejects a major objection to earlier VASCO-project claims that optical transients drop sharply during geomagnetic storms. The VASCO team has reported more than 100,000 apparent transients on First Palomar Observatory Sky Survey (POSS-I) photographic plates taken 1949–1957. Cann’s prior analysis (2026a) showed a clear dose-dependent decline in transient detections across five Kp-index bins, statistically significant at 3.4 sigma using the Cochran-Armitage trend test.

Critics countered that geomagnetic storms brighten the night sky via enhanced airglow, uniformly lowering plate sensitivity so both stars and transients are missed. Cann’s new work rules out that artifact. The Minnesota Automated Plate Scanner (MAPS) catalog provides stellar detection counts (NSTARS) for 638 POSS-I fields with exact observation dates. Cross-matching these counts against the GFZ Potsdam Kp archive reveals essentially zero correlation (Spearman ρ = 0.017, p = 0.673, 0.4 sigma). Normal star detections remain stable while transient detections decline, demonstrating the suppression is source-specific.

This preprint, which has not yet completed peer review, combines the new test with four prior independent checks via Fisher’s combined-probability method to reach an overall 4.9–5.5 sigma significance. Methodology is straightforward but powerful: archival stellar counts serve as an internal control for plate sensitivity on the exact same exposures used for the transient search. Sample size (638 fields) is modest by modern standards yet sufficient for the non-parametric statistics employed; limitations include possible MAPS catalog biases for crowded fields and the fact that POSS-I plates predate precise digital photometry.

The result connects to overlooked patterns. Beatriz Villarroel’s earlier VASCO papers (e.g. arXiv:1906.11473 and AJ 2021) already flagged an excess of vanishing stars across a century of plates, raising questions about rare atmospheric or near-Earth optical phenomena. A 2022 study in Nature Astronomy on space-weather impacts (arXiv:2203.07891) documented how coronal-mass-ejection-driven ionospheric disturbances can alter ground-based transient surveys, but those authors focused on modern CCD data and missed the historical photographic record. What most coverage has ignored is the implication for data validity itself: space weather is not merely noise; it can selectively mask or reveal entire classes of short-lived events, forcing astronomers to treat geomagnetic context as a first-order variable rather than a curiosity.

The findings therefore do more than rebut one objection. They tighten the case that these transients are physically real and tied to terrestrial or near-Earth processes that geomagnetic storms modulate—possibly upper-atmospheric glows, satellite re-entries invisible to radar in the 1950s, or still-unidentified phenomena. The work highlights a blind spot at the intersection of heliophysics and transient astronomy that deserves dedicated follow-up with both archival rescans and modern all-sky monitors.