arXiv subjects

Kevin Cann

Publications and source records attributed to Kevin Cann.

3 recordsLinked to original sources

arXiv2026

Plate Sensitivity Is Invariant Across Geomagnetic Storm Intensity at Harvard and Palomar: A Protocol for Artifact Control in Historical Plate Archive Studies

Historical photographic plate archives anchor a growing body of time-domain astronomy, but time-domain claims drawn from them are vulnerable to plate-sensitivity variations correlated with environmental modulators that can mimic real astrophysical signals. I present a simple, broadly applicable protocol for testing such artifact hypotheses: regress catalog-aggregate reference-population metrics (stellar detection counts or plate limiting magnitudes) against the suspected modulator. Under the artifact hypothesis, the reference metric varies systematically; under the null hypothesis, it does not. I apply the protocol to test whether geomagnetic storm activity, measured by the planetary Kp index, modulates plate sensitivity at two independent observatories. At Harvard College Observatory, the DASCH DR7 archive provides limiting magnitudes for 12,510 exposures across 500 sky positions: no significant trend across Kp bins (Spearman rho = -0.011, p = 0.234). At Palomar, the MAPS Catalog of POSS-I records stellar detection counts for 638 fields: no significant trend (Spearman rho = 0.017, p = 0.673). Plate sensitivity is invariant across the full range of geomagnetic activity at both sites. The principal airglow-based artifact objection to recent claims of Kp-dependent transient suppression in the POSS-I archive is directly falsified at two observatories.

astro-ph.IM↗

arXiv2026

Storm-Driven Suppression and Post-Storm Enhancement of Photographic Plate Transient Detections at Geosynchronous Altitude: Empirical Evidence and a Candidate Dusty Plasma Mechanism

The VASCO project has identified over 100,000 sub-second optical transients on photographic plates from the First Palomar Observatory Sky Survey (1949-1957), all predating artificial satellites. Cann (2026a) established that transient detection rates are dose-dependently suppressed during geomagnetic storms (Z = -3.391, p = 0.0007), ruling out emulsion defects and confirming the transients as real, magnetospherically coupled phenomena. Villarroel et al. (2022) constrained the source altitude to ~42,000 km (geosynchronous orbit) through an Earth-shadow deficit. This paper presents two results. First, a pre-registered empirical test reveals the full temporal recovery profile: transient rates remain suppressed at 55% of baseline during days 7-21 post-storm, then rise to 309% of baseline during days 25-45 (p = 0.00066, Wilcoxon rank-sum; all robustness checks significant). Combined with the dose-response staircase, the overall significance reaches 3.6-4.7 sigma (Fisher's method, range reflecting sensitivity to the independence assumption). Second, we propose a candidate physical mechanism: storm-enhanced electromagnetic trapping of charged micrometeoroid dust at L ~ 6.6, followed by aggregation of icy cometary grains under restored cold plasmaspheric conditions. A flux dilution analysis demonstrates that specular reflection from a partially reflective icy aggregate only 1-4 m in diameter suffices to produce the observed plate magnitude at 42,000 km. This mechanism connects the VASCO transients to independently observed magnetospheric dust swarms correlated with geomagnetic activity (Sommer 2024) and explains the extinction of the transient population following the onset of the space age. Multi-site replication is required to confirm these results.

astro-ph.IM↗

arXiv2026

Geomagnetic storm suppression of photographic plate transient detections in the POSS-I archive: an independent physical variable strengthening the nuclear test correlation

Bruehl & Villarroel (2025) reported a correlation (p = 0.008, 2.6 sigma) between atmospheric nuclear weapon tests and photographic plate transient detection rates in the Palomar Observatory Sky Survey (POSS-I) archive, independently replicated by Doherty (2026) using negative binomial regression with weather controls. I identify geomagnetic storm activity, measured by the planetary Kp index, as an additional independent variable modulating transient rates in the same dataset. Transient detection rates follow a monotonic dose-response across five Kp intensity bins, from 17.4% during geomagnetically quiet periods to 2.4% at Kp 8-9 (Cochran-Armitage trend: Z = -3.391, p = 0.0007). Nuclear test days are not geomagnetically quieter than the baseline; they are slightly more storm-influenced. A multivariate logistic regression including Kp and lunar-phase controls strengthens the nuclear-transient correlation from 2.6 sigma (p = 0.009, OR = 1.53) to 3.1 sigma (p = 0.002, OR = 1.70). The dose-response rules out emulsion defects and spectrally inert orbital debris as the primary transient source, indicating a population physically coupled to the radiation belt environment at geosynchronous altitude. A self-contained reproduction script is provided as supplementary material.

astro-ph.IM↗