arxiv: 2605.01190 · v1 · submitted 2026-05-02 · 🌌 astro-ph.IM · astro-ph.EP· astro-ph.SR

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Statistically Significant Linear Alignments Among High-Confidence Transient Candidates on POSS-I Photographic Plates

Brian Doherty

Authors on Pith no claims yet

Pith reviewed 2026-05-09 18:47 UTC · model grok-4.3

classification 🌌 astro-ph.IM astro-ph.EPastro-ph.SR

keywords transient candidatesPOSS-I plateslinear alignmentshigh-altitude objectsVASCO catalogMonte Carlo testsgeographic projection

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The pith

Linear alignments among high-confidence transients on POSS-I plates project to constant geographic longitudes.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The paper finds seven photographic plates from the 1949-1957 Palomar Sky Survey with linear alignments of five to eight point-like transient sources that are statistically significant compared to random expectations. These alignments, when projected onto Earth's surface assuming the sources are high-altitude objects, mostly show constant longitude with very low probability of occurring by chance. The sources do not repeat at the same sky positions on other nights and are less common near the ecliptic plane than expected for solar system objects. This suggests a class of fast-moving high-altitude objects existed before any artificial satellites were launched.

Core claim

Statistically significant linear alignments of 5-8 high-confidence transient candidates appear on seven POSS-I plates, exceeding Monte Carlo expectations, and project to constant geographic longitudes with sub-degree spread when assuming high-altitude objects, with combined significance around 3e-10, all predating Sputnik 1.

What carries the argument

Machine learning classification to select high-probability transient candidates followed by a search for narrow collinear groupings and geographic projection tests.

Load-bearing premise

The machine learning classifier selects genuine transients without spatial biases, and the linear groupings and constant-longitude projections come from real high-altitude moving objects rather than plate artifacts or unmodeled systematics.

What would settle it

If an independent classification method or a different set of plates yields no such alignments or longitude constancy, that would falsify the interpretation of real high-altitude objects.

Figures

Figures reproduced from arXiv: 2605.01190 by Brian Doherty.

**Figure 1.** Figure 1: Sky coverage of the 635-plate parent VASCO v4 sample. Each circle marks a POSS-I view at source ↗

**Figure 2.** Figure 2: Plate XE429 (1955 March 22). Left: POSS-I red plate showing 5 of 7 aligned sources within a 1.7 arcsec strip spanning 75 arcmin. This date falls within a U.S. nuclear test window, and the alignment projects to within 0.2 ◦ of the Hanford nuclear production complex. Right: The same field on POSS-II (∼1990s). All five source positions are empty (1.7–2.6σ). Confirmation rate: 5/5. All five aligned sources are… view at source ↗

**Figure 3.** Figure 3: Zoomed cutouts for the five aligned sources on plate XE429. Each row shows one source; view at source ↗

**Figure 4.** Figure 4: Plate XE143 (1952 July 30). Left: POSS-I red plate showing all 5 aligned sources within a 1.5 arcsec strip spanning 89 arcmin. Right: POSS-II. Four sources are absent (green circles; 0.4– 1.6σ). One source (red circle, bottom right) is a persistent star (11.5σ). Confirmation rate: 4/5. All five aligned sources are shown in detail in view at source ↗

**Figure 5.** Figure 5: Zoomed cutouts for the five aligned sources on plate XE143. Four sources (T1–T4) view at source ↗

**Figure 6.** Figure 6: Sub-zenith projection of close pairs (< 30 arcsec, same plate) at GEO altitude (35,786 km). Left: low-probability control sample (n = 845). Right: high-probability sample (n = 189). Red stars mark U.S. nuclear-relevant longitudes (Hanford, Nevada Test Site, Los Alamos, Pantex, Offutt AFB, Oak Ridge, Savannah River). Green dashed/dotted lines mark Palomar’s geographic latitude and longitude. The high-probab… view at source ↗

**Figure 7.** Figure 7: Zoomed cutouts for the six aligned sources on plate XE564 (1954 May 24). All six are view at source ↗

**Figure 8.** Figure 8: Zoomed cutouts for the six aligned sources on plate XE105 (1952 August 12). Five sources view at source ↗

**Figure 9.** Figure 9: Spatial and statistical properties of high-probability VASCO transients. (a) Close pair view at source ↗

read the original abstract

I report the detection of statistically significant linear alignments and anomalous spatial clustering among high-confidence transient candidates in the VASCO catalog of vanishing sources on Palomar Observatory Sky Survey (POSS-I) photographic plates (1949-1957). A machine learning classifier scores 107,875 candidates by their likelihood of being genuine transients. Searching the 36,215 candidates with probability >= 0.50 for collinear groupings narrower than 3 arcsec, I find 7 plates with alignments of 5-8 sources that exceed Monte Carlo expectations (p < 0.03, 10,000 iterations). The aligned sources are point-like, not streaks, which rules out any continuously luminous object crossing the field during the 45-minute exposures. The implied angular rates (1-15 arcsec/s) overlap with the geosynchronous regime but are inconsistent with low or medium Earth orbits, and no artificial satellites existed during the POSS-I era. When I project each alignment onto Earth's surface assuming a high-altitude object, 6 of 7 maintain constant geographic longitude with sub-degree spread (combined p ~ 3e-10). Four of these cluster near -96 deg longitude (central United States); one falls within 0.3 deg of the longitude of the Hanford nuclear production site on a nuclear test window date. Close pairs (< 30 arcsec) occur at 16.2x the random rate, and the nights with alignments are the same nights with excess close pairs (Fisher exact p < 0.0001). Plate artifacts cluster near the ecliptic plane (26%), but high-confidence transients are depleted there (16%; chi-square test p = 3.3e-82), which rules out asteroids, comets, and zodiacal debris as the dominant source. No transient reappears at the same sky position on a different night. All of these transients predate Sputnik 1.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Desk Editor's Note private letter to a colleague

The alignments pass Monte Carlo on the high-probability subset but the ML classifier step risks manufacturing the linear patterns without further controls.

read the letter

The main takeaway is that the paper reports 7 plates showing 5-8 point-like transients aligned within 3 arcsec at Monte Carlo p below 0.03, plus a combined p near 3e-10 when those lines are projected to constant geographic longitude under a high-altitude assumption. That is the core claim, and it is new in its combination of ML scoring on the VASCO catalog, narrow-alignment search, and Earth-surface projection test applied to pre-Sputnik plates. The work does a few things cleanly: the 10,000-iteration Monte Carlo gives a direct null for the alignment count, the excess close pairs and the strong ecliptic depletion (chi-square p = 3.3e-82) serve as useful internal checks, and the point-source morphology correctly excludes continuously luminous crossing objects. Those elements are reproducible from the stated methods. The soft spots sit mainly in the selection pipeline. All results are conditioned on the 36k candidates above probability 0.5, yet the abstract and available description give no ablation on that threshold, no feature-importance check, and no demonstration that the alignments weaken or vanish when the cut is relaxed or removed. If the classifier picks up on local density, orientation, or plate-position cues, the retained sources can contain excess linear groupings even when the raw detections do not. The longitude-projection step also assumes the objects are high-altitude and moving in a specific way; alternative explanations such as residual plate defects or scanning artifacts receive less direct testing. Multiple-testing adjustments for the chosen alignment width and group sizes would strengthen the p-values. This is the sort of paper that will interest researchers who work on historical transients or unexplained plate anomalies. A reader who wants quantitative checks on pre-1957 sky data will find the statistics worth examining, but most will want the full classifier details and artifact controls before accepting the high-altitude interpretation. The quantitative framing and clear statistical tests are sufficient to send it for peer review rather than desk reject, though the referees will need to press on the selection bias and null-model assumptions.

Referee Report

3 major / 3 minor

Summary. The paper reports statistically significant linear alignments of 5-8 point-like high-confidence transient candidates (ML probability >=0.50) on 7 POSS-I plates, with Monte Carlo p<0.03 from 10,000 iterations on the 36,215 selected sources; projections of these alignments to Earth's surface assuming high-altitude objects yield constant geographic longitudes with sub-degree spreads (combined p~3e-10), interpreted as evidence for unknown high-altitude moving objects in the 1949-1957 era, supported by excess close pairs and depletion near the ecliptic.

Significance. If the result holds after addressing selection effects, it would be a notable anomaly in historical survey data with potential implications for transient detection methods and unidentified high-altitude phenomena; the direct Monte Carlo test of alignment significance is a methodological strength that provides a clear falsifiable framework.

major comments (3)

[Section on candidate selection and ML classifier (near abstract and methods)] The central statistical claim relies on the post-hoc subset of 36,215 candidates with ML probability >=0.50; no ablation is shown demonstrating that the reported alignments (or their p<0.03 significance) persist when the threshold is varied, removed, or when the full 107,875 candidates are used, leaving open the possibility that the classifier introduces spatial biases favoring linear patterns.
[Monte Carlo simulation description and alignment search] The Monte Carlo null hypothesis assumes positions drawn from a spatially uniform or plate-specific random process independent of the classifier; if the ML features correlate with local density or orientation, the selected sample can contain excess alignments even under the null, undermining the p<0.03 and combined p~3e-10 results.
[Alignment detection and Earth projection analysis] The specific choices of 3 arcsec alignment width and 5-8 source groups, along with the high-altitude projection assumption for longitude constancy, are load-bearing for the headline result; the paper should test robustness across a range of widths/group sizes and show sensitivity of the sub-degree longitude spread to assumed altitude.

minor comments (3)

[Abstract and ML methods] Clarify in the abstract and methods whether the ML classifier was trained with any spatial or positional features that could inadvertently favor alignments.
[Results section on the 7 plates] Provide a table listing the exact p-values, source counts, and longitude spreads for each of the 7 plates to allow direct assessment.
[Discussion of implied rates] The statement that 'no artificial satellites existed' should be qualified to 'no publicly known artificial satellites' given the era.

Simulated Author's Rebuttal

3 responses · 0 unresolved

We thank the referee for their careful and constructive review of our manuscript. The comments correctly identify areas where additional robustness checks would strengthen the statistical claims, and we have revised the paper to incorporate these analyses while preserving the original methodology and results.

read point-by-point responses

Referee: The central statistical claim relies on the post-hoc subset of 36,215 candidates with ML probability >=0.50; no ablation is shown demonstrating that the reported alignments (or their p<0.03 significance) persist when the threshold is varied, removed, or when the full 107,875 candidates are used, leaving open the possibility that the classifier introduces spatial biases favoring linear patterns.

Authors: We agree that the choice of the ML probability threshold of 0.50 is post-hoc and that demonstrating robustness is important. The threshold was applied to isolate high-confidence candidates as defined in the methods, but we have added an ablation study in the revised manuscript. This includes repeating the full alignment search and Monte Carlo analysis for thresholds of 0.40, 0.50, and 0.60, as well as for the unthresholded sample of 107,875 candidates. The number of plates showing significant alignments and the associated p-values remain consistent (p < 0.05) across these cases. We also added discussion noting that the classifier relies on morphological features rather than spatial density or orientation, which limits the scope for introducing linear biases. revision: yes
Referee: The Monte Carlo null hypothesis assumes positions drawn from a spatially uniform or plate-specific random process independent of the classifier; if the ML features correlate with local density or orientation, the selected sample can contain excess alignments even under the null, undermining the p<0.03 and combined p~3e-10 results.

Authors: The Monte Carlo procedure draws random positions for the fixed number of selected sources per plate, as described in the methods. We acknowledge that this null does not explicitly model potential correlations between ML scores and local image properties. However, the classifier features are limited to point-like morphology, absence of streaks, and photometric consistency, with no explicit spatial or density inputs. To address the concern, we have expanded the methods section with a justification of this independence and added a supplementary test applying the classifier to synthetic plates containing injected random and aligned sources; the alignment significance is not artificially enhanced. The reported p-values are therefore retained but now presented with this additional context. revision: partial
Referee: The specific choices of 3 arcsec alignment width and 5-8 source groups, along with the high-altitude projection assumption for longitude constancy, are load-bearing for the headline result; the paper should test robustness across a range of widths/group sizes and show sensitivity of the sub-degree longitude spread to assumed altitude.

Authors: The 3 arcsec width was chosen to match the typical seeing disk and to isolate tight alignments, while groups of 5-8 sources were those that first exceeded the Monte Carlo threshold. We have added robustness tests in the revised manuscript, varying the alignment width from 2 to 5 arcsec and the minimum group size from 4 to 9 sources. The set of plates with significant alignments remains largely unchanged, and the combined p-value for the longitude clustering stays below 10^{-8}. We also tested the geographic projection at altitudes ranging from 100 km to 40,000 km; the sub-degree longitude constancy holds for all assumptions above approximately 500 km, supporting the high-altitude interpretation without altering the headline conclusions. revision: yes

Circularity Check

0 steps flagged

No significant circularity detected

full rationale

The paper identifies linear alignments via a search over ML-scored candidates, then evaluates their frequency against Monte Carlo simulations drawn from independent random position distributions on each plate. The constant-longitude projection test applies an external geometric mapping to the already-selected alignments and computes a combined improbability under the same null model. No reported p-value, significance, or derived quantity reduces by construction to a parameter fitted from the alignments themselves, nor does any load-bearing step rely on a self-citation whose content is unverified or tautological. The derivation therefore remains self-contained against the stated external benchmarks.

Axiom & Free-Parameter Ledger

2 free parameters · 2 axioms · 0 invented entities

The central claim rests on the machine learning classifier producing unbiased transient scores and the assumption that statistical outliers correspond to physical high-altitude objects rather than data artifacts; no new entities are postulated.

free parameters (2)

probability threshold = 0.50
Threshold of 0.50 used to select the 36,215 candidates for alignment search.
alignment width = 3 arcsec
Maximum width of 3 arcsec defining collinear groupings.

axioms (2)

domain assumption The machine learning classifier assigns scores that reflect genuine transient likelihood without spatial selection biases.
Invoked when filtering candidates for the collinear search on the 36,215 sources.
domain assumption Point-like linear alignments on photographic plates indicate real moving objects at high altitude rather than plate defects or scanning artifacts.
Central to ruling out artifacts and interpreting the constant-longitude projections.

pith-pipeline@v0.9.0 · 5657 in / 1921 out tokens · 98214 ms · 2026-05-09T18:47:37.357726+00:00 · methodology

discussion (0)

Reference graph

Works this paper leans on

4 extracted references · 2 canonical work pages · 2 internal anchors

[1]

2021,Advances in Space Research, 67,

Blake, J.A., Sherwin, P., Chote, P., et al. 2021,Advances in Space Research, 67,

2021
[2]

Machine Learning Supports Existence of Previously Unrecognized Transient Astronomical Phenomena in Historical Observatory Images

Bruehl, S., & Villarroel, B. 2025,Scientific Reports, 15, 34125. Bruehl, S., Doherty, B., Streblyanska, A., & Villarroel, B. 2026, arXiv:2604.18799. Busko, I. 2026, arXiv:2603.20407. Doherty, B., et al., in prep. Doherty, B. 2026b,Cross-Archive Replication of the Earth Shadow Deficit in Historical Photo- graphic Plate Transients, arXiv:2604.00056. Solano,...

work page internal anchor Pith review Pith/arXiv arXiv 2025
[3]

2020,The Astronomical Journal, 159,

Villarroel, B., Soodla, J., Comeron, S., et al. 2020,The Astronomical Journal, 159,

2020
[4]

A Response to paper Critical Evaluation of Studies Alleging Evidence for Technosignatures in the POSS1-E Photographic Plates by Watters et al. (2026)

Villarroel, B., Solano, E., Guergouri, H., et al. 2025,PASP, 137, 104504. Villarroel, B., et al. 2026, Commentary, arXiv:2602.15171. 20

work page internal anchor Pith review Pith/arXiv arXiv 2025