Transients in the Palomar Observatory Sky Survey

[John J.]

The million-dollar question has never been whether the objects are present on the plates.

I do sort of wonder whether the features on the reproduced images of the plates identified as transients by Solano, Villarroel et al. are actually all present on the original plates, and if some methodological error or reprographic process might have caused an under-representation of such features within Earth's shadow (or an over representation elsewhere) when studying the reproduced images.

 

[JMartJr]

I've always favored the intermittent spouting of space whales, myself.

Reference to:
1) Star Trek
2) Star Wars
3) Futurama
4) Avatar sequels
5) other?

 

[jdog]

Reference to:
1) Star Trek
2) Star Wars
3) Futurama
4) Avatar sequels
5) other?

Add Doctor Who and Pinocchio in Space...

 

[John J.]

I've always favored the intermittent spouting of space whales, myself.

Reference to:
1) Star Trek
2) Star Wars
3) Futurama
4) Avatar sequels
5) other?

6) Unfortunate but apparently happy whale brought into existence by Heart of Gold's infinite improbability drive, The Hitchhiker's Guide to the Galaxy
7) Star Whale in Doctor Who, "new" series 5 ep. 2 https://en.wikipedia.org/wiki/The_Beast_Below

Edited to add (8) Extraterrestrial whale in 2000 AD's strip Damnation Station. Encountered in an ocean of an alien planet, but implied to have travelled there from outside our galaxy. The premise of the strip is that a powerful ET civilization in our galaxy, The Host, tolerates our existence as long as (often unwilling or unbalanced) human combatants hunt down and destroy any species entering the galaxy from outside. Dark stuff.

 

[NorCal Dave]

One thing I find rather curious is her claim that "the objects are there and look exactly as they do in the digital images." Well… yes. Has anyone seriously argued otherwise?

Isn't this a response to the Hambly & Blair paper? They suggest some of the transients could be from the digitizing process, something they were actually involved with. At the very least, one would need to eliminate those transients that appear in digital formats, but not on the original plates.

Maybe a bit of a Strawman argument? The basic push back on all of these studies is there are a number of things that could have caused these transients that should be eliminated before going to aliens. Obviously, if a transient is an emulsion defect on the original plate, it would still "look exactly as they do in the digital images" but be useless when trying to correlate aliens being interested in nuclear tests.

 

[Andreas]

Obviously, if a transient is an emulsion defect on the original plate, it would still "look exactly as they do in the digital images" but be useless when trying to correlate aliens being interested in nuclear tests.

Indeed. It will be very interesting to read the upcoming report. One can only hope that it provides a detailed account of how the plates were examined to determine whether the transients were caused by defects. To be honest, however, I suspect that the conclusions will remain open to interpretation.

 

[HoaxEye]

You flagged the right strengths: ML-filtered search, Monte Carlo nulls, etc..

Provenance: yes, the paper doesn't confirm individual objects on the original emulsion. It never claimed to. It's a statistics paper on the high-confidence subset, scoped that way in plain text, with Hambly & Blair cited. That caveat applies to every analysis on the digitized POSS-I material, not to alignments specifically. "Provenance is open, therefore the pattern is fake" is a category error you'd flag in anyone else's argument.

Geography: The longitude clustering is partly geometry, north/south alignments on tracked plates plus Palomar's zenith bias. It's flagged as suggestive. Arguing it isn't a hit, it's agreeing with the caveat.

The part nobody wants to touch is the ecliptic depletion. That's the actual result. Thats the strongest part of the paper.

I don't think that's a category error. "Open provenance" doesn't make the pattern fake by definition. It limits how far the interpretation can be pushed. That matters, because the paper does not stop at "interesting structure in the catalogue" but goes on to discuss geosynchronous altitude, fixed meridians, Hanford, and SAC, even while noting that the longitude effect is partly geometric on sidereally tracked plates.

I also think there's a broader tone issue: the wording tends to sound more settled than the actual evidential position. This paper's title itself is stronger than what the full text warrants once the caveats and correction schemes are read closely.

Yes, the ecliptic depletion is probably the strongest internal result in the paper. What I don't think follows is the stronger claim that this makes the effect robust against photographic/instrumental artefacts in general: the result is still about an ML-selected subset of a copy-derived POSS-I catalogue, not a validation on the original negative.

 

[HoaxEye]

Another recent arXiv that seems worth adding to the pile is @Ivo Busko Fast Astronomical Transients in Archival Photographic Plates: Using optical aberrations as a tool for discerning real images, from plate artifacts. Source: https://arxiv.org/abs/2606.08319 (PDF attached)

The interesting part is that it is not another DSS/POSS-I catalogue-statistics paper: Busko uses the APPLAUSE archive and a different telescope/data stream, then argues that a small set of transient images show the local coma aberration expected from off-axis point sources that passed through the telescope optics, which ordinary plate artefacts would not naturally reproduce.

That makes it a potentially useful independent line of evidence that at least some historical "transients" were produced by real light entering the telescope, not just generic local blemishes on the plate. But the paper is also quite a bit more cautious than some of the social-media framing around it: Busko explicitly says the results are preliminary, that the method is still largely visual, that the goal is not a statistically rigorous analysis yet, and that the argument only invalidates the plate-artifact hypothesis "at least for these transients" rather than for all reported cases

So, interesting paper: absolutely yes, independent and potentially important, yes. "Final nail in the coffin" for contamination-based hypotheses in general, no

 

[HoaxEye]

So, interesting paper: absolutely yes, independent and potentially important, yes. "Final nail in the coffin" for contamination-based hypotheses in general, no

Villarroel on X:

Source: https://x.com/DrBeaVillarroel/status/2064285561653727309

PhD astronomer and former NASA engineer Ivo Busko has single-handedly driven a final nail into the coffin of the contamination-based hypotheses (e.g. plate defects and cosmic rays) proposed to explain the VASCO transients.

Again: the paper doesn't support claims like this

 

[jarlrmai]

I think the author has posted here before and maybe could offer their insight @Ivo Busko

 

[Brian Dunning]

Funny, I just finished a show on this. Damn it was a lot of research, and I got to talk to the folks at the secure archives where the original glass plates are stored. Super crazy fun research project.

I found early on that there was no point following Bruehl & Villarroel down their statistical analysis rabbit hole — that entire branch is a red herring.

I hadn't previously realized that Villarroel had been beating this drum for years, and that the debunks were already 100% thorough a year before Bruehl & Villarroel wrote their two papers that went viral in the mass media and brought this to the attention of the larger UFOlogy community.

It was pretty funny that Villarroel's published response to Hambly & Blair lectured them on their own glass plates — maybe she didn't realize that Edinburgh holds the ACTUAL glass plates that her SuperCOSMOS scans had been made from!!! Hambly & Blair had direct access and were able to examine them microscopically, and using emulsion holes from outside the image area as controls, proved beyond any reasonable doubt that's all that her "transients" were. As I said in the show, she brought a knife to a gunfight on that one!!

 

[NorCal Dave]

Again: the paper doesn't support claims like this

Maybe not, but will Busko say that publicly on X, directly challenging Villarreol?

 

[Gary C]

Funny, I just finished a show on this. Damn it was a lot of research, and I got to talk to the folks at the secure archives where the original glass plates are stored. Super crazy fun research project.

I found early on that there was no point following Bruehl & Villarroel down their statistical analysis rabbit hole — that entire branch is a red herring.

I hadn't previously realized that Villarroel had been beating this drum for years, and that the debunks were already 100% thorough a year before Bruehl & Villarroel wrote their two papers that went viral in the mass media and brought this to the attention of the larger UFOlogy community.

It was pretty funny that Villarroel's published response to Hambly & Blair lectured them on their own glass plates — maybe she didn't realize that Edinburgh holds the ACTUAL glass plates that her SuperCOSMOS scans had been made from!!! Hambly & Blair had direct access and were able to examine them microscopically, and using emulsion holes from outside the image area as controls, proved beyond any reasonable doubt that's all that her "transients" were. As I said in the show, she brought a knife to a gunfight on that one!!

LInk?

 

[jarlrmai]

Perhaps these microscopic investigations can be made public?

 

[Andreas]

Funny, I just finished a show on this. Damn it was a lot of research, and I got to talk to the folks at the secure archives where the original glass plates are stored. Super crazy fun research project.

Wonderful! I'm looking forward to it. Here in Sweden, Villarroel is frequently featured in the media, making all sorts of claims without ever facing critical questioning. Journalists often struggle to understand her assertions and therefore tend to simply quote her rather than challenge them.

 

[NorCal Dave]

Perhaps these microscopic investigations can be made public?

They should be in the Hambly and Blair paper, right? IIRC, one of the arguments was that H&B only looked at a few plates and only in a few areas.

 

[JMartJr]

They should be in the Hambly and Blair paper, right? IIRC, one of the arguments was that H&B only looked at a few plates and only in a few areas.

Which might be a way of saying "they looked at a representative sample and learned enough," but saying it in a way that minimizes what they did?

 

[Andreas]

One aspect of Busko's findings that I find more interesting than the coma analysis itself is the extreme clustering. If I understand the data correctly, all 11 candidates occur within a narrow time window (roughly 1949–1953) and in just two small regions of the sky. Several also appear in small temporal groups.

Regardless of whether the objects are "real" or not, this seems significant. If they represent a genuine astronomical or atmospheric phenomenon, why would it be so tightly confined in both time and sky position? On the other hand, if the clustering reflects something in the observational chain (plate batches, observing programs, telescope configuration, processing methods, etc.), that might naturally explain both the temporal and spatial concentration.

To me, the key question is not yet "What are the objects?" but rather, "Why do they appear only in these years and these fields?" Am I wrong here? I don't really have enough knowledge of the subject to draw any conclusions of my own, but as a layman, that is my spontaneous reaction.

 

[Andreas]

Villarroel recently posted this in a Swedish Facebook group, commenting on a post in which someone suggested that the UFO community follow Mick West and Metabunk for a more nuanced approach.

Translated to English:
"The scientific method is not the same thing as the process of elimination used by many prominent ufologists, even though there is often some overlap in methodology. Analytical methods (which are generally good methods) are often misrepresented as the scientific method; the difference is that the former can provide you with an explanation, while the latter can tell you whether that explanation actually holds up. Just because you can find a natural explanation does not mean it is the correct one, and that is where the scientific method is needed. If you want to investigate UFO cases using the scientific method, I highly recommend reading analyses produced by 3AF-Sigma2 in Paris."

I think this is relevant to understanding her views and thoughts on the scientific process.

 

[John J.]

[Quoting Beatriz Villarroel] "If you want to investigate UFO cases using the scientific method, I highly recommend reading analyses produced by 3AF-Sigma2 in Paris."

Sigma2 is a subgroup of French aerospace interest group 3AF (Association Aéronautique et Astronautique de France, https://www.3af.fr/en/about-3af/mission-6531) that is interested in UFO reports.

One of the articles on their website is "About Joint work between SIGMA2 3AF and Dr. Jacques Vallée", Nadia Tronche, 15 April 2026
https://www.3af.fr/en/news/about-joint-work-between-sigma2-3af-and-dr-jacques-vallee-2519;

I would like to pay tribute to Dr. Jacques Vallée for the work carried out jointly with the SIGMA2 Technical Commission of 3AF. In particular, we performed analyses of material samples and a study of the radiation emitted by a pulsed light sphere (the Haynesville case, 1966, Louisiana, USA), on which we co-authored an article published in the journal Progress in Aerospace Science with the active support of Dr. Jacques Vallée and members of 3AF SIGMA2 (1)​ (Luc Dini, Geoffrey Mestchersky).

The paper Tronche refers to is "Estimates of radiative energy values in ground-level observations of an unidentified aerial phenomenon: New physical data", Jacques F. Vallée, Luc Dini , Geoffrey Mestchersky 2025, Progress in Aerospace Sciences Vol. 156.
Its abstract and some other extracts are viewable via Science Direct https://www.sciencedirect.com/science/article/abs/pii/S0376042125000247
What appears to be a pre-publication draft is viewable via 3AF at https://www.3af.fr/global/gene/link...-aerial-phenomenon-new-physical-data.pdf&fg=1, PDF below. The text appears to be identical to the published extracts of the published paper viewable at Science Direct.

The researchers estimate the energy output of a claimed glowing spherical UFO based on its estimated distance from some scorched bark collected by the claimant, a nuclear physicist, Louie A. Galloway. Another source they use is the claimant's estimate of the distance at which the glow of his car's headlights was "overwhelmed" by the light from the claimed sphere. I don't find these convincing as reliable methodologies.

One of the bark samples had an elevated level of caesium 137. The authors consider possible sources, including accidents at US nuclear power stations. But having dwelt on Galloway's profession earlier in the paper, they seem to forget it here. Maybe he, or a colleague/ contact, had access to trace amounts of caesium 137 and, er, accidentally contaminated the sample?
It appears there has been no study of the bark samples since 1978, a quick casual reading of the paper might suggest to an unwary reader that the 2026 authors had conducted studies (in fairness they do not claim this), they have not.

There is (as in another paper Vallee co-authored) text that implies the authors of this paper spoke with someone (here, Edward Condon) in connection with it/ the case it refers to, when in fact the only author involved in claimed communication with Condon appears to be Vallee, many years earlier (my emphasis)

Following our communication with him, Dr. Condon concurred and his group undertook extensive follow-up studies...

...but Condon died in 1974, Wikipedia https://en.wikipedia.org/wiki/Edward_Condon

There are extraordinary claims made without evidence,

High-energy events are not rare in the context of UFO/UAP reports. ...Among the latter effects are injuries... ... as well as long-term conditions that occasionally require hospitalization and can lead to death. Physical impact (apart from known mechanical effects) is most often in the form of light energy (many cases trigger photocells in cities and villages) and detrimental impact on irradiated plants, as in this case.

There are contradictions, at least in 3AF's pre-publication copy, from 6.6 Sample examination

When we examine sample A, we might expect to see only the outer surface blackened, as we know that only this side was exposed to the
phenomenon/object. This is not the case, both the outer and inner of the sample are blackened while the interior remains unaffected. It is on that basis that more accurate estimates of energy could be made...

...and from 8.3. Preliminary results and challenges,

The solution space is complex and currently contains multiple unknowns including: ...The extent of the charring (maybe one of the most crucial ones): without detailed information on the depth and uniformity of the charring, it is difficult to fully validate the approach or reduce the dimensionality of the problem.

If Villarroel finds analyses produced by 3AF-Sigma2 particularly convincing, that is up to her. I don't think this paper is without problems. Perhaps there are other studies she could point to that are more persuasive than this one.

 

[RobertBillyBob]

Sigma2's director Luc Dini seems to be closely linked to the usual suspects.

He is one of the numerous co-authors of the "New Science of UAP" papers

He organised a seminar with Mellon and Vallée

https://www.3af.fr/fr/news/reunion-...t-cnews-et-france-2-2389?id_details_groupe=43

Sat between Vallée and Villaroel during the same seminar

There is a UAP semniar planned at the french National Assembly later this month with Dini as a participant. I've been doing some research on the french UAP interest group in anticipation. I may start a thread about it later.

 

[Andreas]

Sigma2's director Luc Dini seems to be closely linked to the usual suspects.

Yeah, well, I think this is quite telling. Also, here's a direct quote from a text written by Villarroel in 2024:

"To break this cycle, we need to focus on clear hypotheses for what we believe we are studying, no matter how crazy or stigmatized such ideas appear to be. We need to drop the discussion about "UAP" and "UFO" and talk about clear concepts e.g. flying saucers or glowing orbs. We should not be afraid to talk about extraterrestrial artifacts or non-human spaceships and how to test if such can be found. A flying saucer or a glowing orb has clear distinctive physical features that can be looked for in a survey."

It's interesting that she appears to know exactly what clear, distinctive physical features a flying saucer possesses. More importantly, these ideas should be kept in mind when evaluating her conclusions about the transients. I'm not arguing that this undermines her findings, but it may represent a source of ET bias.

 

[FatPhil]

Yeah, well, I think this is quite telling. Also, here's a direct quote from a text written by Villarroel in 2024:

"To break this cycle, we need to focus on clear hypotheses for what we believe we are studying, no matter how crazy or stigmatized such ideas appear to be. We need to drop the discussion about "UAP" and "UFO" and talk about clear concepts e.g. flying saucers or glowing orbs. We should not be afraid to talk about extraterrestrial artifacts or non-human spaceships and how to test if such can be found. A flying saucer or a glowing orb has clear distinctive physical features that can be looked for in a survey."

It's interesting that she appears to know exactly what clear, distinctive physical features a flying saucer possesses. More importantly, these ideas should be kept in mind when evaluating her conclusions about the transients. I'm not arguing that this undermines her findings, but it may represent a source of ET bias.

I don't think she's saying that, I think she's saying the Right Thing (TM). I think she's saying that we shouldn't consider the meaningless catch-all terms that describe things in the LIZ as in any way meaningful, and that we should try to restrict ourselves to more meaningful terms, but only once their referrent has been demonstrated to have distinctive enough features to warrant use of that term. For example, to call something an "orb", we must be able to see its spacial extent clearly enough that it is clearly spherical rather than any other shape (so we must have evidence that not just supports a hypothesis, but which actually contradicts the alternative hypotheses). I can salute that flagpole.

Which of course contradicts what she does in her papers, so either her cognitive dissonance baffles are highly effective, or my charitable interpretation of the above is completely wrong.

 

[flarkey]

I don't think she's saying that, I think she's saying the Right Thing (TM). I think she's saying that we shouldn't consider the meaningless catch-all terms that describe things in the LIZ as in any way meaningful, and that we should try to restrict ourselves to more meaningful terms, but only once their referrent has been demonstrated to have distinctive enough features to warrant use of that term. For example, to call something an "orb", we must be able to see its spacial extent clearly enough that it is clearly spherical rather than any other shape (so we must have evidence that not just supports a hypothesis, but which actually contradicts the alternative hypotheses). I can salute that flagpole.

Which of course contradicts what she does in her papers, so either her cognitive dissonance baffles are highly effective, or my charitable interpretation of the above is completely wrong.

I tend to agree with you here @FatPhil that this is a good thing, but I dont think it contradicts what she does in her papers. In the paper Aligned, multiple-transient events in the First Palomar Sky Survey (Villarroel et al 2025) she does hypothesise about the possible shapes that could produce glints and transient flashes in astronomical images. Sadly these shapes are purely hypothetical, untestable and unfalsifiable, but at least it is an attempt to move away from the amorphous 'orb' shape description.

Source.

 

[Eburacum]

This 'shape' theory should be testable; how slowly would these objects need to rotate if they rarely appear more than once per plate, and how fast would they need to rotate in order to show a glint lasting less than a second? These two constraints seem to be mutually exclusive.

 

[Andreas]

I don't think she's saying that, I think she's saying the Right Thing (TM). I think she's saying that we shouldn't consider the meaningless catch-all terms that describe things in the LIZ as in any way meaningful, and that we should try to restrict ourselves to more meaningful terms, but only once their referrent has been demonstrated to have distinctive enough features to warrant use of that term.

Perhaps you're right, but when reading the whole article, one becomes a bit more concerned. Her conclusion is:

"Maybe it was the most brilliant manipulation in history to stigmatize the term "flying saucer" and reshape the problem into a dumping category as "UFO" and "UAP", as this truly affects our thinking and capability of solving this issue that has bugged our society for 70 years. But if we keep talking about UAP and UFO, we can almost guarantee that no solution will come in the next hundred years either."

There are several problems that should be addressed here. First of all, she's implying that the stigmatization of flying saucers and the introduction of UFO as a name for unidentified objects was some kind of deliberate manipulation, a way to prevent scientists from studying the "phenomenon." More generally, she often argues that the term UFO leads us down the path of debunking, and that this is a bad thing. Perhaps she's right, but the problem is that there isn't any evidence of shiny flying discs from outer space for scientists to study. She's talking about an issue "that has bugged our society for 70 years," but what issue, and what society? My interpretation is that she finds studies of "UFOs" rather useless, since the only thing one can do is debunk or identify anomalies. Therefore, she wants scientists to be open-minded and instead study specific phenomena such as flying saucers or orbs.

She gives one example here:

"Are there any physical objects with anomalous properties or materials left behind at locations where a flying saucer either landed or crashed?"

The problem is that, when you skip the step of determining whether there is a genuine phenomenon (such as alien flying saucers) to study, such research becomes highly problematic. The reason why such studies haven't been conducted by serious scientists is perhaps the simple fact that we have no evidence of flying saucers ever landing or crashing on Earth.

This part of the article also has close links to her research on transients. She asks:

"Is there any correlation between aircraft accidents or disappearances and "UFO sightings" or hotspots? How about boat accidents or disappearances and USO sightings?"

Apparently, abbreviations such as UFO and USO are useful after all. Even though she recently dismissed them, arguing that they are useless and filled with unidentified, uninteresting clutter, she still relies on them here. To me, it seems that on the one hand she is arguing for the study of concrete "phenomena" such as alien spacecraft and probes, while on the other she is still willing to look for statistical correlations between "UFO reports" and events such as aircraft disappearances. Let's say we know why an airliner went down from an investigation conducted by the NTSB, and let's say we know that the UFO reported around the same time was probably caused by misidentification and a lack of data. In such a case, looking for a statistical correlation seems rather pointless.

This is obviously a more general discussion, but it ties in with the transients. If she had simply claimed to have found some unexplained dots in the digital images, I wouldn't have a problem with the whole thing. It's obviously worth researching. But from the outset, she set out on a quest to find traces of alien spaceships or probes in the vicinity of Earth. To me, finding these transients is similar to finding the blurry distant dots in the FLIR videos. We can see that something is there, but we don't know what it is. In the absence of sufficient data, a fantastic explanation can be tempting for some.

 

[Eburacum]

I note that the article says 'each object spins around an axis that also has precession', which means the object need not ever show the same surface to the telescope in any given period. Basically saying that these satellites are spinning all over the place, which would make monitoring the Earth problematic.

One wonders why satellites in geosynchronous (not geostationary) orbits would be expected to have a good view of the Earth in any case - they would be 35 thousand kilometres away from the surface. Spy satellites are generally much closer.

 

[Andreas]

I note that the article says 'each object spins around an axis that also has precession', which means the object need not ever show the same surface to the telescope in any given period. Basically saying that these satellites are spinning all over the place, which would make monitoring the Earth problematic.

One wonders why satellites in geosynchronous (not geostationary) orbits would be expected to have a good view of the Earth in any case - they would be 35 thousand kilometres away from the surface. Spy satellites are generally much closer.

Yeah, it makes little sense. But the beauty of it is that it doesn't have to make sense, since extraterrestrial probes or satellites are hypothetical objects, and there's no reason to assume they would function like human technology. That's why I don't really buy her reasoning when she says, "A flying saucer or a glowing orb has clear, distinctive physical features that can be looked for in a survey." Do they really? Or isn't it the case that their supposed physical features can always be adjusted to fit whatever data happens to be collected?

 

[flarkey]

One wonders why satellites in geosynchronous (not geostationary) orbits would be expected to have a good view of the Earth in any case - they would be 35 thousand kilometres away from the surface. Spy satellites are generally much closer.

Presumably they think that any civilisation that has the ability to put objects in geosynchronous orbit around Earth would have such advanced technology that they can monitor us from a distance. But then that poses the question as to why they have to fly down to Earth to monitor the Nuclear Tests upclose resulting in the sightings reports from the UFO witnesses.

Its almost like they are just making this stuff up as they go without thinking it through.

 

[jarlrmai]

Yeah, it makes little sense. But the beauty of it is that it doesn't have to make sense, since extraterrestrial probes or satellites are hypothetical objects, and there's no reason to assume they would function like human technology. That's why I don't really buy her reasoning when she says, "A flying saucer or a glowing orb has clear, distinctive physical features that can be looked for in a survey." Do they really? Or isn't it the case that their supposed physical features can always be adjusted to fit whatever data happens to be collected?

Yup aliens can be as advanced or as limited as you need them to be to fit your theory.

 

[jdog]

I don't think she's saying that, I think she's saying the Right Thing (TM). I think she's saying that we shouldn't consider the meaningless catch-all terms that describe things in the LIZ as in any way meaningful, and that we should try to restrict ourselves to more meaningful terms, but only once their referrent has been demonstrated to have distinctive enough features to warrant use of that term. For example, to call something an "orb", we must be able to see its spacial extent clearly enough that it is clearly spherical rather than any other shape (so we must have evidence that not just supports a hypothesis, but which actually contradicts the alternative hypotheses). I can salute that flagpole.

Which of course contradicts what she does in her papers, so either her cognitive dissonance baffles are highly effective, or my charitable interpretation of the above is completely wrong.

The whole "transients correlate with nuclear tests and UAP sightings" debacle leaves me less inclined to interpret her other claims charitably.

 

[Andreas]

Read something I found a bit interesting. Yesterday, Avi Loeb wrote about the latest batch of UAP files released, calling them "the Most Intriguing Release Thus Far." Hm, intriguing is probably not the word I would use, but that's not something we should discuss in this thread. Interestingly, he's also mentioning the transients in the same text. When talking about 'The Central Intelligence Agency and Overhead Reconnaissance: The U-2 and OXCART Programs, 1954–1974' (Pedlow & Welzenbach, 1992), he's suddenly mentioning the transients, saying the following:

"This revelation makes one wonder whether glints of sunlight from test flights during the 1950s of U2 airplanes or their equivalent versions developed in the Soviet Union, could explain the transient lights reported on photographic plates from the 1950s in the pre-Sputnik era."

I find this statement quite remarkable. Not because it's anything new—people have obviously been talking about high-altitude jets as a possible solution for a long time. And he's not in any way describing his idea in more detail, making it more of a quick thought than a hypothesis. But the timing is quite interesting. Recently, the discussion surrounding Villaroel's research has become quite heated. He's obviously quite aware that Villarroel and her associates find the airplane hypothesis highly implausible. Yet, in this context, he's decided to speculate that the transients could simply be glints of light from shiny airplane hulls.

I have no strong views on his ideas per se, but I think one can detect a subtle distancing from Villarroel's increasingly uncompromising stance. This is particularly noteworthy given that she has raised the tone of her arguments recently. Not even the man speculating about Oumuamua being a spaceship seems to be fully aboard.

 

[Eburacum]

Whether these 'transients' were caused by glints from aircraft or from satellites, it is unlikely they would all last for less than a second. Nearly every satellite glint I've seen, visually or in a photo, has been a streak.

 

[John J.]

[Referring to Avi Loeb] When talking about 'The Central Intelligence Agency and Overhead Reconnaissance: The U-2 and OXCART Programs, 1954–1974' (Pedlow & Welzenbach, 1992), he's suddenly mentioning the transients, saying the following:

"This revelation makes one wonder whether glints of sunlight from test flights during the 1950s of U2 airplanes or their equivalent versions developed in the Soviet Union, could explain the transient lights reported on photographic plates from the 1950s in the pre-Sputnik era."

I think this is interesting. I don't know whether Loeb's musing, that reconnaissance aircraft might be responsible for the transients, is a workable hypothesis, but if it is then it's unlikely U-2 flights played a major part. if they did it would be reflected (no pun intended) in a greater frequency of transients in later plates, perhaps concentrated in the last 1% or so to be taken. "Oxcart" played no role whatsoever.

The first photographic plate was exposed on November 11, 1949. 99% of the plates were taken by June 20, 1956, but the final 1% was not completed until December 10, 1958.

Wikipedia, https://en.wikipedia.org/wiki/National_Geographic_Society_–_Palomar_Observatory_Sky_Survey

But the first U-2 test flight wasn't until June 1955. Progress was fast, by March 1956 there were 9 planes and approx. 1000 flying hours logged
(Unlimited Horizons- Design and Development of the U2, Peter W. Merlin, 2015, NASA https://www.nasa.gov/wp-content/uploads/2015/07/unlimited-horizons.pdf)
By June 1956 the U-2 had attained altitudes of approx. 22,700 m, comfortably breaking the 20,080 m record set by a Canberra, August 1955.

The first "Oxcart" (YF-12) flight was in June 1963 (Wikipedia https://en.wikipedia.org/wiki/Lockheed_YF-12), so not a possible cause of transients.

The Yak-25RV, a Russian aircraft sometimes described as performing a similar role to U-2, didn't fly until 1959. (Soviet claims about its performance may be unreliable, and it wasn't used in areas where we might expect a Soviet U-2 equivalent to be used).
And it's a pretty safe bet it was never visible from the Palomar Observatory. How would it get there? No Soviet aircraft carriers, no Communist Cuba until 31 December 1958.

Loeb may have been talking "off the cuff", but he seems to have been wondering if high-altitude aircraft were responsible.
If pretty much any fixed-wing aircraft might be the cause of large numbers of pseudo-transients, which are hard to distinguish from actual astronomical transients, I feel the wider astronomical community would have pointed this out to Villarroel et al. pretty quickly, as it would be a familiar problem. Commercial aircraft must vastly outnumber secret military test flights in the skies around the observatory, and probably did in the 1950s. Area 51 is relatively close to Mount Palomar (276 miles, 444 km) but only 104 U-2s were built over 34 years from 1955 (Wikipedia https://en.wikipedia.org/wiki/Lockheed_U-2).

If altitude is a factor in hypothetical spy planes being transients, that sort of leaves us with the more modest Canberra, which entered UK service in January 1950.
The USAF adopted a heavily Americanised version, the Martin B-57 which was accepted into service in March 1953. But the B-57 was optimised for close air support, and had a ceiling of just 13,745 m (Wikipedia https://en.wikipedia.org/wiki/Martin_B-57_Canberra).
The USAF further modified 20 aircraft as RB-57s for high-altitude (approx. 21,300 m) recce, Wikipedia https://en.wikipedia.org/wiki/Martin_RB-57D_Canberra, which came into service from April 1956, again too late for the overwhelming majority of the POSS1 plates.
The direct Russian equivalent to the Canberra /B-57 was the Ilyushin Il-28, introduced 1950 but with a modest ceiling of 12,300 m, and like the Yak it wouldn't be troubling California.

So YF-12 (Oxcart) is too late to have played a role, U-2 entered service in modest numbers very much toward the end of the first 99% of the plates being produced. Likewise the twenty RB-57s. The main B-57 types used by the USAF were not high altitude machines.
Realistically, we can rule out Soviet aircraft or non-US Canberras (or any other foreign type, come to that).

I think it's unlikely that the small number of U-2s and RB-57s available while the last few percent of POSS1 plates were being taken had much impact. Whether aircraft more generally [edited to add, not just high-altitude types] might be responsible for some, I don't know, but if they are I think astronomers would be well aware of the issue, perhaps with a rough idea of how many they might expect to see in any given exposure (taking time and area of sky being imaged into account).

(This is sort of apart from what we might read into why Loeb raised this possibility, and what it might indicate about his views on Villarroel et al.'s claims; as pointed out by @Andreas this could be very interesting).

 

[JMartJr]

Whether these 'transients' were caused by glints from aircraft or from satellites, it is unlikely they would all last for less than a second. Nearly every satellite glint I've seen, visually or in a photo, has been a streak.

I suppose that would hold for light reflecting off of some "UFO spaceships from Omicron Peresei 8?"

 

[John J.]

I suppose that would hold for light reflecting off of some "UFO spaceships from Omicron Peresei 8?"

Maybe they need to be seen, but not to the extent that us dogmatic close-minded types who might upset cosmic harmony are persuaded.
They're separating the wheat from the chaff...

 

[Andreas]

(This is sort of apart from what we might read into why Loeb raised this possibility, and what it might indicate about his views on Villarroel et al.'s claims; as pointed out by @Andreas this could be very interesting).

Yeah, it seems a bit odd if the transients were the result of high-altitude airplanes, but personally, I don't know enough about the technical details surrounding how the photographs were taken to say whether that's possible or not. Still, it's somewhat surprising that Loeb is prepared to "trivialize" Villarreal's research with such an offhand remark. There's no real reason for him to start talking about the transients in the article, but he does so anyway. Suggesting that they could be the result of something as simple as airplanes can be interpreted as an acknowledgment that they might be caused by something mundane, such as glints of sunlight from aircraft (or perhaps balloons). It's probably unwise to speculate about his motives for making such suggestions, but as a reader, I get the impression that he regards the transients as being far from proof of any anomalous phenomenon.