Transients in the Palomar Observatory Sky Survey (POSS-I) may be associated with nuclear testing and reports of unidentified anomalous phenomena

Bruehl and Villarroel analyze daily transient, nuclear-test, and UAP-report data for 2,718 days from November 19, 1949 through April 28, 1957.

A dataset comprising daily data (11/19/49—4/28/57) regarding identified transients, nuclear testing, and UAP reports was created (n = 2,718 days).

The authors report transients on 310 days, above-ground nuclear tests on 124 days, and UFOCAT reports on 2,428 days within the study period.

transients were observed on 310 days (11.4%).

The paper reports a transient relative risk of 1.45 within the test-date-plus-or-minus-one-day window, with a 95% confidence interval of 1.10–1.90.

the relative risk ratio for a transient to occur when within a nuclear test window (relative to being outside of a nuclear test window) was 1.45 (95% Confidence Interval: 1.10 – 1.90).

A secondary timing analysis reports transients on 18.5% of days immediately after a nuclear test versus 11.0% of other days, a 68% relative increase.

Transients were observed on 18.5% of days that were 1 day following a nuclear test, whereas transients were noted on only 11.0% of days not meeting this criterion.

Among the 310 days with transients, the study reports a small positive rank correlation between transient counts and UAP reports: rho 0.138, p=0.015.

between the total number of transients and total UAP reports on a given date (Spearman’s rho = 0.138, p = 0.015).

The negative-binomial model associates each additional UAP report with an 8.5% increase in the number of observed transients.

for every additional UAP reported on a given date, there was an 8.5% increase in the number of transients observed.

The combined-predictor analysis finds the highest transient counts on dates with at least one UAP report that also fall within a nuclear-test window.

dates with at least one UAP report and that were within a nuclear testing window displayed the highest total number of transients.

The authors identify March 17, 1956 as the last transient-positive date within a test window despite 38 subsequent nuclear tests in the study period.

The last date on which a transient was observed within a nuclear testing window in this dataset was March 17, 1956, despite there being an additional 38 above-ground nuclear tests

The authors explicitly state that their results neither definitively identify transients nor necessarily establish causation.

Our findings do not definitively indicate what transients are nor do they necessarily imply causal associations.

The authors propose an unknown atmospheric effect of nuclear tests and artificial reflective objects as competing hypotheses for the associations.

an unexpected and previously undocumented atmospheric phenomenon triggered by nuclear detonations or related to nuclear fallout

The paper argues that diffuse fallout contamination differs from the discrete point-source appearance of the transients.

Contamination of photographic plates by nuclear fallout produces diffuse fogged spots quite different in appearance than the discrete star-like brightness profiles

The authors acknowledge that only a small subset of the automated transient detections received manual confirmation.

While a small subset of these have been subjected to manual confirmation

The study acknowledges that UFOCAT reports were not systematically validated, that one observatory is compared with worldwide events, and that transients may have multiple causes.

reports in the UFOCAT database that provided UAP data for the current work have not been evaluated for validity in any systematic way.

Transient selection requires a red-plate point source absent in preceding and later images, with no Pan-STARRS DR1 or Gaia DR3 counterpart within five arcseconds.

there were no counterparts either in PanStarrs DR1 or Gaia DR3 at less than 5 arcsec.

The authors selected the three-day nuclear-test window while blinded to transient data; the finer two-day-before through two-day-after windows were post-hoc analyses.

This decision to use a 3-day window as the primary nuclear testing outcome was made while the authors were still blinded to the transient data.

The UFOCAT preparation retains one entry per discrete report and further groups same-date, same-state reports to reduce duplicate observations.

only a single entry for each discrete report was retained.