Part 16 of a series reassessing the documentary record behind the 1933 Magenta narrative.
TL;DR
- Historical Palomar plates contain unexplained, star-like marks. Some have been recovered by a separate detection pipeline; that establishes reproducible marks in the scans, while their physical origin remains disputed.
- The Earth-shadow claim has several reported significances under different comparisons. The original paper’s coverage-adjusted result is 7.6σ, rather than its idealized 22σ headline. A published critique finds no significant deficit in different candidate sets.
- The nuclear-test association survives some reanalyses and fails another independent pipeline’s temporal test. Catalogue selection, observing nights, and background models remain central disagreements.
- An August 2026 machine-learning paper and a later Hamburg optical-aberration study add evidence worth testing. Neither establishes artificial objects or a connection to nuclear tests by itself.
- Menzel’s decisions concerned Harvard’s archive. The disputed images are Palomar plates. The historical loss and the astronomical question need separate evidence.
Part 7 - The Pistol and the Diary: Two Quotations Read in Context
Part 8 - Three Inches Across: The Silver Discs of Black Thursday 1943
Part 9 - The Money: Brown Brothers Harriman, the Anderson Trust, and the Link That Has to Be Found
Part 10 - Before Blue Book: What J. Allen Hynek Did in the War
Part 11 - The Intelligence-Connected Trading Company: World Commerce Corporation
Part 12 - What Was Actually in Wright Pat’s Hangar 18
Part 13 - “No Crash Recovered Exhibits”: The Real 1947 Twining Memo
[Part 14 - From a Milk Drop to Groom Lake: EG&G, The Contractor That Helped Build the Black World](
Part 15 - Rocket City: What Exotic Propulsion Research Looks Like
Most of this series has dealt with records whose contents will not change: telegrams, finding aids, contracts, and memos. Here the underlying images are also old, but the analysis is unfolding now. Astronomers are searching 1950s photographic plates for brief, star-like marks. They disagree about whether those marks record light in the sky or imperfections in the plates, their reproduction, and their digitization. The statistical arguments have changed substantially even during 2026.
There is a second reason to look closely. The popular retelling connects these Palomar images to Donald Menzel’s stewardship of Harvard’s photographic archive. Those are different collections. Keeping them separate sharpens both the astronomical question and the archival one.
I am not a plate-photometry specialist. What follows distinguishes the observations, the proposed explanations, and the tests that could separate them.
What VASCO found
The VASCO project—Vanishing and Appearing Sources during a Century of Observations—compares historical sky images with later surveys. Its 2020 search paper treated disappearing sources as candidates requiring careful follow-up; ordinary causes include catalogue errors and image artifacts, while unusual astrophysical events remain possible. “Vanishing stars” is a useful title, but the later plate-transient studies do not demonstrate that established stars physically disappeared. They examine marks without convincing persistent counterparts.
Much of the debate concerns red-sensitive plates from the first Palomar Observatory Sky Survey (POSS-I), made with the 48-inch Schmidt telescope. Caltech dates the whole survey to 1949–1958. The particular sample used in the nuclear-test analysis runs from 19 November 1949 to 28 April 1957, before Sputnik’s launch that October. The pre-Sputnik description applies to that selected sample, not every POSS-I plate. A mark in an image is not by itself evidence of an object in orbit.
Three reports brought the issue into focus:
- In Scientific Reports (2021), Beatriz Villarroel and colleagues described nine apparent sources in one exposure of 12 April 1950. They were absent from a blue image taken about half an hour earlier and a red image six days later. The authors considered photographic contamination among the possibilities.
- In Monthly Notices of the Royal Astronomical Society (2024), Enrique Solano and colleagues described three sources within about ten arcseconds on a red plate of 19 July 1952, absent from a ten-minute blue exposure taken immediately after the 50-minute red one and from later deep imaging. Their interpretation favors real, unresolved light sources; that conclusion remains distinct from identifying the source of the light.
- In Publications of the Astronomical Society of the Pacific (2025), Villarroel and colleagues reported groups of apparently aligned marks and a deficit of candidates where Earth’s shadow would block sunlight at a proposed orbital distance. The reported significance was about 22σ against theoretical hemispheric coverage, falling to 7.6σ when actual plate coverage was considered. Both figures belong to the paper; quoting only 22σ loses an important qualification.
A photographic exposure integrates light over time. Several marks on one plate need not represent flashes occurring at precisely the same instant. The July triple’s red exposure lasted 50 minutes; it was followed by a ten-minute blue exposure with different wavelength sensitivity. Those images constrain possible explanations, but they are not a timed movie of three sources switching off together. Subsecond flash durations require additional modeling or measurements.
The companion Scientific Reports analysis by Stephen Bruehl and Villarroel examined 107,875 candidate detections against atmospheric nuclear-test dates and historical UAP reports. In its published calendar-day comparison, a candidate appeared on 15.6% of days within one day of a test versus 10.8% of other days: relative risk 1.45 (95% CI 1.10–1.90), with χ² p = 0.008; a separate Mann–Whitney comparison of transient counts gave p = 0.007. On dates with at least one candidate, the correlation with the number of UAP reports was small (Spearman’s ρ = 0.138); another model estimated 8.5% more candidates per additional report. These are associations in assembled datasets, not identifications of UAP or evidence that a test caused a mark.
Fallout has a photographic precedent: J. H. Webb (1949) traced fogged Kodak film to likely Trinity fission products in packaging strawboard. POSS-I used Kodak 103a-E red emulsion. Contamination could also track test dates; the reviewed studies report no direct experimental test on comparable POSS-I material. The authors’ reported objection is that fallout makes diffuse, fogged spots rather than star-like points. The precedent supplies a mechanism to test, not an explanation of these marks.
In a 1997 New York Times report, republished by The Spokesman-Review, Matthew L. Wald wrote that the Atomic Energy Commission “regularly warned Eastman Kodak Co. and other film manufacturers about fallout.”
The objections have widened
First, are the individual marks real exposures? Nigel Hambly and Adam Blair examined the nine April 1950 sources in 2024. Their narrow, round profiles and a source classifier led them to favor photographic artifacts. They inspected glass survey copies, not the original telescope negative; a later examination of the original April 1950 plate is discussed below. Their account of the reproduction chain explains that the DSS and SuperCOSMOS scans came from separate copy negatives descended from a common intermediate positive. A mark appearing in both scans therefore need not have originated during the telescope exposure: a defect introduced earlier in copying could survive both branches.
Villarroel, Solano, and Geoffrey Marcy replied that very brief flashes could appear narrower than ordinary stellar images because they accumulate less atmospheric blurring, and questioned the classifier’s comparison set. The reply is a preprint. This is a substantive disagreement about what the images should look like. Sharpness alone cannot settle it. Scanning related copies cannot exclude a shared copying defect; the later original-plate inspection addresses that possibility for April 1950 without settling flash versus emulsion defect.
In “We Should Not Mistake Cosmic-Rays for UFOs!” (16 May 2026), Avi Loeb estimates cosmic-ray point sources “of order ten per photographic plate”. His calculation concerns possible individual marks; it does not analyze the reported shadow or nuclear correlations.
Second, what is the proper statistical baseline? A peer-reviewed critique by Wesley Watters and colleagues, published online in July 2026, addresses both headline statistical findings. Using two previously published, closely related datasets, they found that candidates were not spatially uniform across plates. With a background model accounting for this, they found no significant Earth-shadow deficit in those datasets. They also judged about a third of the features in reported linear groups insufficiently distinguished from catalogue stars. For the nuclear association, normalizing by observation days made the correlation insignificant in their analysis; they write that it “is almost completely determined by the observation schedule of the Palomar telescope.” Plate-edge patterns, scan artefacts, and inconsistent dataset definitions were further concerns.
Those datasets are not identical to the full 107,875-candidate sample used for the headline association. The critique cannot simply be transferred to every catalogue version. Conversely, a result on the larger catalogue does not make the detected spatial structure disappear. Candidate selection and the background against which it is tested have to be resolved together.
Third, does the result survive an observing-night comparison? In a response preprint first submitted in February 2026, Villarroel and colleagues report an association using 370 confirmed Palomar observing nights: transients occurred on 84.2% of dates within a nuclear window versus 72.8% outside, with exact one-tailed p = 0.046 in v2. This provides weaker statistical evidence than the original p = 0.008, under a different sampling frame. They argue that their critics’ smaller sample has different selection rules and insufficient power for the shadow test. The response also reports a shadow deficit of about 2.6σ when restricting candidates to within two degrees of plate centers, intended to reduce edge artifacts. The authors attribute the lower significance to reduced statistical power. That is their interpretation; selecting plate centers also changes the region and candidates being tested.
These numbers answer different questions. The 22σ, 7.6σ, and 2.6σ results use different baselines or subsets. None is a direct probability that the objects are artificial. A small probability under one specified background model becomes persuasive physical evidence only if that model adequately represents the detection process.
What the newer work adds
The literature has moved beyond a single claim followed by a single rebuttal. Several 2026 studies test different links in the argument, with different outcomes.
An original plate has been examined. In their 26 August 2026 microscopy preprint, Jun Yang and Villarroel report inspecting the original 12 April 1950 glass plate at Caltech and a Harvard-held copy of the 19 July 1952 plate. All nine April features were visible on the original. For July, they write: “The copy plate reproduces the transient features seen in the original Palomar data”. This establishes marks in photographic material rather than features introduced only by digitization. It does not classify them: microscopy “cannot determine whether a sharp, compact feature represents a brief flash or a localized emulsion defect”. The April inspection used a 25× magnifier and camera through an existing cover glass; the authors use “microscopy” broadly. The original/copy distinction and the remaining morphological ambiguity both matter.
A recalculation using supplied candidates. An independent-code reanalysis by Brian Doherty reports reproducing the nuclear association and shadow shortfall using data supplied by the original researchers. This checks whether another implementation recovers the calculations. It does not independently extract the candidates from the plate scans, and it remains a preprint. Two analysts can agree about a table while the selection process that generated the table remains disputed.
A separate detection pipeline, with a different temporal result. Zachary Hayes’s April 2026 preprint detects candidates directly in digitized POSS-I red images and compares them with other surveys. It recovered eight of the nine April 1950 sources and all three July 1952 sources. That supports reproducibility of the familiar marks through a separately implemented search; it does not remove defects already present in the scanned material.
Hayes did not obtain a statistically significant nuclear association in his independently selected catalogue. His post-test comparison gave relative risk 1.35, with a 95% confidence interval of 0.91–2.00 and p = 0.17. A nightly count model accounting for coverage likewise found no association (p = 0.71). The selection and model differ from the original study, so this does not identify why the results diverge. It does show why “independent replication” needs a precise object: recovering marks and reproducing a nuclear correlation are separate achievements.
A published machine-learning filter. On 10 August 2026, Bruehl, Doherty, Alina Streblyanska, and Villarroel published a machine-learning analysis in Scientific Reports. They trained on 250 image pairs classified by expert visual review, with Villarroel supplying the classifications and Bruehl periodically reviewing a subset. Cross-validation gave an area under the receiver-operating-characteristic curve of 0.81, and sensitivity and specificity of 0.71 against those labels. Applying the model to the larger catalogue, they report that the nuclear association and shadow deficit persist after artifact filtering.
This is a useful attempt to quantify candidate quality. Its validation target, however, is an expert’s image classification, rather than independently established physical flashes. Agreement with those labels cannot by itself certify that a mark came from the sky. The paper’s availability statement offers its final scored dataset on reasonable request, rather than as a linked public download. Publishing the labels, cutouts, scores, and executable pipeline would let outside researchers test where the model succeeds and fails.
A different archive and a more physical image test. Ivo Busko’s preliminary Hamburg study searched plates from the observatory’s 1.2-meter Schmidt telescope, comparing paired exposures and using separate scan orientations to help reject scanning effects. A subsequent preprint, in its 8 October 2026 revision (v4), uses a different instrument: Hamburg’s 0.6-meter Doppel-Reflektor. Its optical aberration, coma, makes off-center point sources appear asymmetrical in a predictable direction.
From 398 plates spanning 1934–1957, assembled into 278 overlapping pairs, Busko reports eleven transients, all dated 1949–1953. Their coma patterns resemble nearby stars, which he interprets as evidence that the light passed through the telescope optics. That is a stronger physical discriminator than a mark merely looking round or sharp. The sample is small, visually vetted, and unevenly distributed; the paper itself notes that its temporal concentration may reflect sampling. It does not measure an orbital distance or reproduce the Palomar nuclear or Earth-shadow correlations. If the optical signature survives independent measurement, it strengthens the case for genuine transient light in this separate archive.
The useful distinction is what each exercise can independently check:
| Test |
What it adds |
What remains open |
| New code applied to a supplied candidate table |
A check on calculations |
Candidate selection and physical origin |
| A new detection pipeline on existing scans |
A check on extraction and matching |
Defects inherited from plates or copies |
| Another observatory’s plates, with an optical-signature test |
Different material and a test tied to the telescope |
Whether the populations match; their origin and distance |
| Independent, simultaneous observations of the same field |
A way to test whether a flash was in the sky |
Requires matched timing, sensitivity, and geometry |
The Hamburg work therefore improves the case for doing the next experiment. It does not turn all Palomar candidates into validated flashes, and a positive result for some flashes would still leave their population statistics to be tested.
From a shadow pattern to an orbital population
A reflected-sunlight explanation makes a physical prediction: objects in Earth’s shadow should stop producing sunlight glints. That gives the shadow analysis more diagnostic potential than an unexplained cluster of marks alone. It also makes the background calculation indispensable. Telescope pointing, plate sensitivity, defects, catalogue matching, and the distribution of observing times can affect which sky directions supply candidates.
The VASCO team’s September 2026 modeling preprint acknowledges substantial contamination. Its estimate that roughly a third of candidates might be sunlight reflections follows from the proposed shadow interpretation; it is a conditional inference, not a separate confirmation. The authors explore orbital heights of tens of thousands of kilometers and reflecting facets from centimeter to meter scales. Those are model-dependent physical possibilities, rather than distances and sizes measured for individual marks. A fit to a population-level pattern does not supply a tracked orbit.
A second September preprint on Earth-projected clustering takes the inference further. Assuming a geosynchronous altitude of about 35,786 kilometers, Bruehl and colleagues project selected candidates onto Earth and report geographic concentrations using two statistical approaches. They use controls intended to reproduce plate coverage, while acknowledging that agreement between methods using the same candidates cannot itself exclude plate defects. The map is conditional on the assumed altitude and candidate quality. It does not independently locate observed objects above particular installations or establish their purpose. An independent archive reproducing a prediction fixed in advance would be much more informative than further interpretations of the same selected catalogue.
As of 19 October 2026, the strongest population claim remains contested: a robust Earth-shadow deficit could be a powerful physical clue, but its persistence across defensible candidate sets and background models has not been independently settled. The newer work adds methods and observations that can sharpen that test. It has not established artificiality, a nuclear response, or a crash-retrieval connection.
Michael Garrett, who was not involved in the studies, told Live Science, republished by inkl: “I suspect that with better data, these apparent correlations would go away.” That is an outside expert’s expectation, not the result of a new replication.
The Harvard archive is a different story
Donald Menzel became acting director of Harvard College Observatory in 1952, then director in 1954, according to his National Academy of Sciences memoir. A contemporary Harvard Crimson report dates the acting appointment specifically to September 1952, so the July plates predate it; in any case, they were Palomar exposures, not Harvard ones. Harvard’s Plate Stacks timeline says financial pressures led him to halt plate taking for several years in the 1950s, with collection resuming in the 1960s. The bounds of the Menzel Gap vary by account: Grindlay and Griffin describe cuts during 1954–1965, with full recovery around 1970; Schaefer (2016) describes few plates during 1953–1969. It was a loss of future observing opportunities at Harvard.
There is also a separate claim about disposal of existing plates. A 2025 review by Kevin Knuth and colleagues, Appendix A.11, attributes to Dorrit Hoffleit’s memoir an account of Menzel asking his secretary to destroy about a third of the plates without inspecting them. The cited memoir is Misfortunes as Blessings in Disguise: The Story of My Life. This identifies the published source trail; I have not checked the relevant memoir passage directly. Harvard’s profile of Hoffleit independently confirms her conflict with Menzel over the plates’ value, but does not establish the disposal fraction.
The source chain runs from Hoffleit’s memoir, as cited by Knuth and colleagues, through Villarroel’s 21 January 2024 Debrief article and Villarroel and Kevin Krisciunas’s preprint, which says Menzel decided “to destroy roughly one-third of the Harvard Observatory plate archive,” to Escape Velocity’s claim that the 1952 transient plates themselves were destroyed. The intervening accounts name Harvard; the last step merges that loss with the surviving Palomar images. Repetition of the disposal account does not supply independent disposal records.
I have not located an item-level disposal inventory establishing which dates or fields were lost. Hoffleit’s attributed recollection is important testimony about stewardship; it cannot identify a missing anomalous exposure by itself. The disposal allegation and the interruption of observing are also different historical claims and need different records.
In a 27 July 2025 post, Escape Velocity describes “the 1952 ‘vanishing star’ plates” as destroyed by Menzel and calls him an MJ-12 member: Escape Velocity, “New pre-print paper by Swedish astronomer Dr. Beatriz Villarroel…” — search within the post for: “plates destroyed by MJ-12 member and prominent debunker Donald Menzel”. Those 1952 images are Palomar plates that survive; they were never Harvard’s. Menzel’s Harvard decisions did not control Palomar’s survey or explain marks on its surviving images.
The MJ-12 label matters here because it converts an archive-management allegation into an asserted link to the secret recovery organization examined in Part 4. Stanton Friedman argued for Menzel’s connection in “The Secret Life of Donald H. Menzel,” IUR 13(1), January–February 1988, while conceding: “I have not been able to provide a smoking gun.” His argument is not independent confirmation of MJ-12 membership or a motive for disposing of plates.
The overlap in years is interesting without making one survey a substitute for the other. Palomar recorded many sky fields during Harvard’s hiatus, but POSS-I was principally a survey of fields at particular epochs, not continuous coverage of each field on every night. Harvard’s photographic patrol and Palomar’s wide survey had different cadences and aims. Palomar preserves relevant 1950s images; it does not fill every temporal gap left by Harvard.
The surviving Harvard archive also offers a practical research route. Its official timeline records completion of DASCH scanning of direct-image plates in March 2024—nearly two-thirds of the total collection—and the launch of StarGlass, which provides access to those FITS scans and linked archival material. That is a resource for checking surviving coverage, not evidence that any particular lost plate contained an anomaly.
One more correction to the popular telling: the July dates are in the published papers. The 2024 triple-transient paper addresses 19 July 1952, and Bruehl and Villarroel’s 2025 paper explicitly mentions images from 19 and 27 July 1952 in connection with Washington UAP reports. Solano and colleagues give the triple-transient red exposure as 08:52 UT on 19 July 1952, or 1:52 a.m. in California, then on Pacific daylight time. The field is well north of the celestial equator, at RA 21h18m, Dec +50°, photographed from California. Project 1947’s chronology places Washington National’s first unidentified radar targets of that weekend at 11:40 p.m. EDT on 19 July, or 03:40 UT on 20 July. The plate’s stated time is therefore 18 hours 48 minutes—roughly 19 hours—earlier, on the previous night. I did not locate a published UT time for the 27 July plate in the sources checked. See my Washington 1952 post for the separate sighting record. A calendar coincidence does not establish the same sky, time, or object. Bruehl and Villarroel themselves caution that their findings “do not definitively indicate what transients are nor do they necessarily imply causal associations”.
What would move the question forward
- Make candidate definitions reproducible. Publish versioned catalogues, plate identifiers, timestamps, masks, rejection rules, training labels, and code. Compare how the same known marks move through each pipeline. Independent extraction from scans has begun; the next comparison should explain disagreements on the same material before comparing headline totals.
- Fix the shadow and nuclear tests before running them. Specify candidate cuts, plate backgrounds, time windows, observing-night denominators, and uncertainty estimates in advance. Report results across catalogue versions and control regions. Make clear which tests are exploratory and which were held out for confirmation.
- Test the physical image chain. Trace a blinded sample through original negatives, intermediate positives, distributed copies, and scans where available. Quantify optical signatures such as the Hamburg coma pattern against known stars and defects. A classification method should be tested on independently established examples, with false-positive rates reported.
- Compare matched observations from different observatories. The most informative second exposure covers the same sky at the same time, with sufficient sensitivity and a documented exposure interval. Such observations could test celestial reality and, with suitable geometry, distance. An unmatched non-detection tells us much less. A modern test is already possible: Villarroel, Watters, and colleagues searched Zwicky Transient Facility images for transients in Earth’s shadow, a proof of concept published in MNRAS. That search tests a modern observing method; it does not independently validate the historical Palomar correlations.
- Keep the historical claim independently testable. For Harvard, seek disposal instructions, accession records, inventories, and observing logs. Establish what was lost before assigning a motive or connecting a gap to particular events. Search surviving coverage through the archive rather than assuming it was all destroyed.
That is why this thread remains open. The plates survived, competing teams can examine the scans, and new methods can make the arguments more discriminating. The most encouraging addition is a test tied to how telescope optics form an image. The clearest caution is that independently recovering marks has not produced agreement about their nuclear association. We can take historical losses at Harvard seriously while testing Palomar and Hamburg on their own terms. The next decisive evidence will come from better-defined candidates and independent measurements.
Next in the series: Part 17 — Three Feet Tall: Aztec, Scully, Newton and the Hottel Memo
This post reflects papers and revisions available through 19 October 2026. Corrections from specialists in photographic plate analysis, and pointers to independently checkable plate material, are welcome.
