H.W. Peiniger / World’s First: Passive Radar Signal Confirms visual UFO-Sighting
Translation by Andreas Müller, GreWi.de, original article published in JUFOF
THIS ARTICLE IS A SUM OF TWO ARTICLES REPUBLISHED WITH AUTHORIZATION AND CANNOT BE REPRODUCED WITHOUT THE AGREEMENT OF THE AUTHORS
Luedenscheid (Germany) – Worldwide, private passive radar systems are increasingly being used in UFO research. In Germany, members of the “Society for the Investigation of UFO Phenomena” (GEP) also operate such systems. For the first time, one of these systems has successfully and independently confirmed a UFO sighting in real time – an unprecedented milestone in research.
– The original German version of this article can be found here
The following article is a guest contribution by Hans-Werner Peiniger for the German „Society for the Investigation of UFO Phenomena e.V.“ (GEP), originally published in the association’s journal „Journal für UFO-Forschung“ (JUFOF, 01-2025, Vol. 46, No. 277).
Incident Details
The witness, an employee of the Federal Police in Offenburg, was returning home from a night shift and parked in front of her house. Upon exiting her car, she heard a loud noise coming from the southern sky, which she described as “the dragging of a metal chain over asphalt”. Looking up, she saw a very bright, white, “wave-like“ formation in the clear sky. In front of the wave-like structure, she observed a bright, vertically aligned “double dot”. The sound stopped, and at the same time, the phenomenon disappeared. She estimated the sighting lasted no more than 5 seconds.
Case Summary
Case Number: 20240920 B
Date: September 20, 2024
Time: 05:34 AM CEST
Location: 77948 Friesenheim – Oberweier, Germany
Witnesses: Name known to investigator
Classification: NL
Assessment: GOOD UFO
Identification: None
Investigations: On hold
First Contact: Email, September 20, 2024
Investigator: Josef Garcia
UPDATE 04.03.2025, 18.00h:
Find the original radar datea and all technical details of the used passive radar instruments here: https://doi.org/10.5281/zenodo.14949908
At the same time, the witness’s husband was preparing breakfast in the kitchen and heard the loud noise through the open balcony door. However, he described it differently, saying it sounded “like many small beads falling onto a tiled floor”. He did not step outside but found the unusual noise noteworthy for that early hour.
The witness was able to specify the exact time of the incident because she glanced at her Apple Watch, which displayed the time in large digital numbers (she uses this feature while jogging).
She lives approximately 1,000 meters from GEP investigator Josef Garcia, whom she knows personally and informed about the event shortly afterward. Unfortunately, Garcia was in the shower at the time of the event and did not hear anything, nor did his wife, who was still asleep.
For professional reasons, the witness wishes to remain anonymous. However, she emphasized that she had never seen anything like this before.
Discussion and Assessment
A detailed interview with the credible eyewitness by Josef Garcia provided no further insights. Investigations into an independent source for the perceived noise yielded no results. The phenomenon was visible for only a very brief time, leaving the witness with no opportunity to observe additional details.
Josef Garcia is GEP’s expert on passive radar, a valuable tool in technical UFO research. We previously reported on the technology and its applications in UFO research in JUFOF 257, 5-2021.
Both Garcia and GEP operate a station that continuously monitors part of the sky using passive radar.
Since the unusual luminous phenomenon appeared within the coverage area of Garcia’s passive radar station, it made sense to check the recorded signals from the time of the sighting. Indeed, the passive radar had captured a signal that closely matched the witness’s sketch. We can therefore assume that the luminous phenomenon observed by the witness was the cause of the passive radar signal. This event is unprecedented worldwide. To our knowledge, this is the first time a UFO/UAP sighting has been confirmed using passive radar.
The radar recording also provides additional insights. The screenshot shows a time span of approximately 50 seconds. The interval between the left-side timestamps is roughly six seconds. The time is recorded in UTC, so two hours must be added to match Central European Summer Time.
The witness heard the sound, looked up, and saw the unusual light phenomenon. It is unclear whether the luminous phenomenon was already in the sky when she first noticed it. However, if we assume it was indeed detected by the passive radar, then it must have been visible for only a very short time. Had it remained in the sky longer, the radar track visible in the screenshot would have looked different—it would have shown longer vertical amplitudes, and the two leading lights would have appeared as extended vertical streaks. If the luminous phenomenon had been moving, its track would have had a different shape. The passive radar signal confirms that the light phenomenon was stationary in the sky.
The signal also indicates that the phenomenon was visible in the sky for only slightly less time than the witness estimated—likely just over two seconds instead of the estimated five. This speaks to the witness’s precise observational skills.
Since the phenomenon was detected by passive radar, it must have been a tangible, luminous object rather than an immaterial „pure light phenomenon,“ comparable to an aircraft, helicopter, or meteoroid, all of which can also be registered by passive radar.
How Do We Assess This Case?
Can we identify anomalous characteristics that justify classifying this as a UFO? I believe so.
Sound Characteristics
The witness assumed the sound she heard was caused by the luminous phenomenon. The passive radar data confirms that the light phenomenon was visible for only a short time. The sound was also brief, suggesting a possible connection between the two. Whether the sound originated from the object itself or resulted from an atmospheric effect remains unclear. It must have been quite loud, as the witness’s husband heard it clearly from inside the house. Interestingly, his description of the sound differed from his wife’s. This could be due to individual auditory perception or the way the sound was altered by the building’s structure.
Visual Appearance
The light phenomenon’s appearance is highly unusual and does not match any known UFO stimuli.
One could speculate about unconventional scenarios, such as a nighttime Zeppelin flight with a specific lighting configuration. However, this would be highly unlikely at that early morning hour. A review of air traffic data confirmed that no conventional aircraft were present in the area at the time.
Brief Duration
The short duration of the sighting is another anomaly. If a conventional aircraft had caused the phenomenon, it would likely have been visible for a longer period. Lightning or similar natural phenomena can also be ruled out, as passive radar does not detect lightning. Moreover, meteorological data confirmed that the sky was clear.
Conclusion
This is a truly extraordinary case, featuring multiple anomalous characteristics and confirmation by passive radar. This confirmation is unprecedented and, to my knowledge, has never been reported anywhere in the world.
Debate over whether to classify this as a PROBLEMATIC UFO CASE or GOOD UFO CASE is certainly possible. However, given the passive radar confirmation and its significance for technical UFO research, I consider a classification as GOOD UFO CASE to be justified.
About the GEP
The Society for the Investigation of UFO Phenomena (GEP, Gesellschaft zur Erforschung des UFO-Phänomens e.V.) is Germany’s largest nonprofit scientific organization dedicated to UFO research. GEP investigates UFO reports using specialized questionnaires, on-site interviews, field research, and thorough background analysis. We work in an interdisciplinary manner and are supported by various governmental and scientific institutions.
© Hans-Werner Peiniger / Society for the Investigation of UFO Phenomena (Gesellschaft zur Erforschung des UFo-Phänomens e.V., GEP)
GEP investigators answer questions about confirming a visual UFO sighting with passive radar.
Lüdenscheid, Germany — Last February, researchers from the Gesellschaft zur Erforschung des UFO-Phänomens e.V. (GEP), the Society for the Investigation of the UFO Phenomenon, reported the first confirmation of a visual UFO sighting through passive radar detection. Following the report on the case, the GEP received numerous critical and constructive questions and comments from readers regarding the sighting, its detection, and the interpretation of the sighting as a "good UFO." In the current issue of the Journal for UFO Research (JUFOF), GEP investigators address these questions and comments.
Due to the GEP's decision to present this extraordinary case to a wider audience via www.grenzwissenschaft-aktuell.de, in addition to the association's magazine JUFOF, where it appeared in an English version, the case attracted considerable national and international interest. Various UFO researchers, podcasts, and YouTube channels picked up the case. Many users discussed the article intensely on social media and in comment sections, with some asking critical questions.
The following is an abridged version of, and selected excerpts from, the GEP article currently published in the Journal für UFO-Forschung (JUFOF 03/2025, Vol. 46, No. 279, pp. 73–85). The article addresses some of the comments and questions raised, "also because we gained new insights from these contributions," according to the authors, Josef Garcia (JG) and Hans-Werner Peiniger.
The JUFOF is the GEP's internal publication. As part of GEP membership, the JUFOF is free, but an annual subscription is also available.
Viewers of the popular YouTube channel LPIndie submitted the following questions and comments, among others:
Question: "If an object transmits on a frequency, do you see a vertical line?"
Answer (JG): An object does not transmit on a frequency; rather, the object provides a reflection.
Quote: "I think it's highly unlikely that this image depicts the object that this person saw..."
Answer (JG): For the phenomenon described to actually appear in the approximate shape shown on the passive radar's waterfall display at exactly that time, it would have to be a very big coincidence.
Quote: "Incidentally, it is not possible to deduce the appearance of the phenomenon from the radar image showing the spectrum because the radar only shows the Doppler effect over time."
JG's response: Good point! However, my passive radar colleagues and I believe that the reflection would have to be longer to show the Doppler effect on the waterfall. For example, consider the International Space Station. The Doppler effect is particularly easy to see when observing the International Space Station on passive radar. The reflection leaves a long, curved trail on the waterfall that can be recorded for several minutes.
Quote: "This could be an ionized trail. In my opinion, it is more likely a meteor 'bouncing' off the atmosphere." ?"
Answer by JG: Also a good point! The typical "fly-in" of a meteor is usually represented by a long flight trail, but this is absent from passive radar. However, it could be possible."
Notably, a viewer living north of Offenburg reported hearing the "chain noise" described by the witness at the same time. This witness lives about 20 kilometers away from the sighting location.
Another witness suggested that a German Armed Forces exercise may have been taking place in the area at that time. I contacted the German Armed Forces Aviation Office and received written confirmation that no such exercises were carried out during the specified period.
Comments from other YouTube channels suggested flocks of birds, kites, or military tests as possible explanations for the passive radar signal. Josef Garcia explains: "Just like flocks of birds, large kites, and rice balloons cannot produce reflections on passive radar and can therefore be ruled out as the cause. We were also unable to find any evidence of military tests." However, mylar balloons, which are usually covered with a wafer-thin layer of aluminum, cannot be completely ruled out as a possible cause. Due to their small size, though, such balloons would have to be in the immediate vicinity of a passive radar station to produce a detectable signal. According to the GEP authors, this aspect can also be applied to other conventional objects, such as drones.
Numerous comments and questions were also posted on the GEP's own YouTube channel.
Question: "Drone with an LED strip."
Answer: In the case of a drone or aircraft, the passive radar would record a continuous flight path as a reflection. However, in this case, the object was only visible for a short time before disappearing, which is exactly what is reflected in the signature detected by the passive radar."
Question: "Can you determine the altitude from the radar image?"
Answer JG: Unfortunately, no. At least two additional passive radar systems would have had to be in operation at a distance of approximately 1,000 meters to do so.
Question: "Possibly a meteor? That would explain the brief appearance and the noise of beads colliding. The waveform could have been caused by the wind blowing the objects apart as they left a trail. The moment the objects became too small due to burning up, they disappeared from the radar. Just an idea."
Answer by JG: Contrary to years of experience and observation of meteor trails on passive radar, this observation lacks the typical "fly-in," i.e., the long trail of a meteor.
Comment: I ran this through Google's new AI model, 3.5, for experimental purposes and received some explanations. The core problem is that the passive radar image shows a structure that resembles an aircraft but has a wavy lower edge. The sketch, which serves as visual confirmation, only shows the wavy line. Below are the explanations that attempt to reconcile the two: Aircraft with banner tow: The passive radar detects the aircraft (hence the aircraft-like parts in the radar image) and the long banner towed behind it. The visual observation (confirmed by the inverted sketch) focuses on the most striking element, the wavy banner. Interpretation of the passive radar image/artifacts: The aircraft-like structures in the image (e.g., wings and tail) may be caused by technical effects, such as interference or multipath propagation, or they may be overemphasized. The "real" signal, which is also visually confirmed by the sketch, is primarily the wavy structure/line. While the radar detected this correctly, it may also have shown interference signals. Formation or swarm: A formation of smaller objects (e.g., drones) or a dense flock of birds could produce a more complex image for passive radar.
Visually, however, this formation could have appeared as a single, undulating line from a distance. This was recorded in the inverted sketch. If none of the above explanations apply, then the object or phenomenon could be an unidentified or unusual phenomenon (UAP). UAPs are objects or phenomena that cannot be easily classified and that exhibit both an unusual radar signature and an unusual visual appearance (e.g., a wavy line, as confirmed in the sketch). The banner tow explanation often bridges the discrepancy between a complex radar image (aircraft and appendage) and a simpler visual observation (only the appendage or movement). However, the AI cannot identify the noises described. If they are related, Gemini 3.5 Pro Experimental actually suggests UAP as the most likely option. More data is needed for further evaluation. Further visual confirmation would also be helpful, including documentation of how it was determined that no aircraft was in flight. I would not rule out an aircraft.
JG responded that, at the time of the sighting, there was also an aircraft in the wider observation area. Its trail appeared as a faint, elongated line on the passive radar. An "advertising banner" is typically made of plastic or fabric. These materials do not produce reflections in passive radar and are therefore not visible in radar recordings. Flocks of birds do not cause reflections in passive radar either. After analyzing thousands of known aircraft tracks, we determined that they typically appear as short, straight lines in the waterfall diagram of passive radar. Therefore, we can rule out with a high degree of certainty that the observed phenomenon is related to an aircraft or drone.
Questions about radar: Since the radar image looks the way it does, does that mean it really had that shape in the sky? Could it be a zeppelin with a neon sign attached to it? Does it have to be a snake-shaped object with two separate objects? How do I read the radar image? Is it like a map in the X and Z directions? Or is the radar image a view of the sky toward the horizon?"
Answer: I assume there are three objects: the wave-shaped trail and two separate points. Unfortunately, the exact flight direction cannot be determined. This would have required at least two additional passive radar systems about 1,000 meters apart. However, a rough direction can be given. On the screen, the right side corresponds to west, and the left side corresponds to east. The receiving antenna itself is aligned southwest towards the horizon."
Question: How can this be verified? What if the eyewitness and the radar owner know each other and want to create a sensational case? For example, what if the radar image existed before the 'eyewitnesses' saw it? I'm not a skeptic, but that would be their first question."
Answer (JG): Such a suspicion is completely unfounded. There is a credible eyewitness report, and the passive radar signal was discovered only during a later review of the recorded signals.
Question: "Thank you for the explanations and the data. Would it be possible to recreate the radar image? For example, what images are produced when static reflectors are made visible in the detection area for a short time? This would probably be difficult to implement in practice."
Answer (JG): Correct, that would be difficult to implement.
Question: I have no idea if this is possible, but could it have been a lightning strike or similar discharge?
Answer (JG): The investigation revealed that there was no lightning during the observation period. A Metabunk colleague (see below) determined the following: "An investigation revealed that there was indeed lightning, but much further south, behind Freiburg im Breisgau, about 50 kilometers from the sighting location, one hour later."
Question: "Interesting...also because of the sound frequencies that the witnesses heard simultaneously. Perhaps further conclusions can be drawn from the spectrum in the upper Hz range?"
Answer (JG): Unfortunately, no further conclusions can be drawn from the received radar data. It is unclear if the loud, chain-like noise is related to the sighting. However, it is interesting that another eyewitness has come forward who also heard the noise at the same time, but around 20 kilometers further north.
The English-language international forum Metabunk.org, run by UFO skeptic Mick West, also picked up on the post from www.grenzwissenschaft-aktuell.de and reported on it. The ensuing discussion raised some important points.
The timestamps displayed on the passive radar system screenshot are in UTC.
It is claimed that there were no conventional aircraft in the area at that time.
Metabunk comment: "I'm not familiar with passive radar, so I don't know if this is an unusual signal. However, if you look at the area on ADS-B Exchange, you'll see that a B752 operated by DHL entered the passive radar coverage at almost the exact moment the signal was detected. ADS-B Exchange's resolution is only 10 seconds, and the article states that the passive radar area is approximate. Nevertheless, it appears to be a very good match in terms of location and time."
JG's response: That is correct! My statement was incorrect. I made a typo when checking air traffic with ADS-B Exchange. At the time of the sighting, there was indeed a DHL aircraft flying west at an altitude of approximately 5,000 meters. However, I proved that the DHL aircraft was not related to the passive radar signal of the UFO sighting. Both radar tracks, that of the aircraft and that of the UFO, are visible separately on the radar image. The DHL aircraft was not the cause of the UFO sighting. A correction was also made in the latest JUFOF.
The image above shows the vertical, interrupted trail of the DHL aircraft's reflection recorded by the passive radar. For a brief moment, the aircraft and the observed phenomenon were within the witness's line of sight and overlapped. The exact distance between the two cannot be determined from the reflection trails. However, it cannot be ruled out that the pilots may have noticed the phenomenon. To do so, they would have had to look in the right direction at the exact moment it appeared. Additionally, the phenomenon would have had to have been large enough to fall within their field of vision. The witness did not notice the aircraft herself, presumably because it was too far away and visually inconspicuous compared to the phenomenon.
Metabunk comment: "Either the phenomenon was not far away, or the noise did not come from it."
JG response: "That is correct; the noise does not necessarily have anything to do with the phenomenon. The sighting location is surrounded by grapevines, and it was grape harvesting season. I thought perhaps a harvesting machine could have made that noise accidentally. However, the witness and the hearing witness have lived in the area for many years, are familiar with the sounds of harvesting machines, and have never heard a noise like that before.
Metabunk comment: "I thought the witness might have observed a lightning strike between the cloud and the aircraft. The wavy line represents the lightning and the two dots represent the wing lights.” These happened to correspond with the aircraft's entry into the passive radar area. The article claims that the sky was clear, but I would like to verify this."
JG response: A check revealed that there was indeed lightning, but it occurred much further south, behind Freiburg im Breisgau, about 50 kilometers from the sighting location, and it happened an hour later. Metabunk checked the weather and found that, as the witness stated, it was cloudless with a clear, starry sky. You can check the lightning strikes here, for example.
Metabunk comment: "On September 20, 2024, only one fireball was reported to AMS in Germany, but it was not a match as it occurred 14 hours later."
Metabunk comment: "I wonder exactly what the eyewitness believes she saw."
JG response: The witness has never seen anything like this before. She doesn't believe in aliens and thinks it was some kind of natural phenomenon."
Metabunk comment: "Is the wavy line a physical object shaped like a wave? Or is it the trail of another object?"
JG response: "I suspect there were three objects."
Metabunk comment: "Are the two dots two separate objects, or are they two lights attached to a single object?"
JG response: Unfortunately, that cannot be determined.
Metabunk comment: "What is the relationship between the wave line in the sky and the radar wave line?"
JG's answer: The wave line observed by the witness cannot be reproduced 100% accurately on the radar wave line with my passive radar equipment. A receiver in this price range—a few hundred dollars—does not offer high-resolution imaging.
On the other hand, professional systems could reproduce the shape and resolution of the object with much greater detail, coming much closer to the witness's description.
Metabunk comment: "Is it a 'radar image' in the shape of a single object?"
JG response: No, it could have been three objects.
Metabunk comment: "Does the radar wave line show the trajectory of the object that created it in the sky?"
JG response: Unfortunately, I cannot answer that. In order to determine the exact trajectory of the object, at least two additional passive radar systems would have needed to be in operation at a distance of approximately 1,000 meters."
Metabunk comment: "On the subject of passive radar: Is the wave line detected a momentary representation of an object, or a trail created over time that shows the movement of an object?"
Answer from JG: It is a momentary representation of one or three objects. The radar signature appears very briefly and then disappears. The image shows the reflection that occurred in a matter of seconds."
Metabunk comment: "Both noise descriptions could refer to noises I have heard before from lightning strikes."
JG's response: According to the records, there was no lightning strike.
Metabunk comment: "This claim can be dismissed immediately as complete nonsense. In the witness's sketch, the y-axis is spatial — more precisely, 'vertical.'" In the radar diagram, as you can see, the y-axis is temporal, and the chirp appears to be about one second long. Likewise, the x-axis is almost certainly horizontal for the draftsman. Unless I am misinterpreting the display, the passive radar measures frequency along this axis. The vertical line is therefore an intermittent pure tone. Space/space vs. frequency/time. Any 'match' is purely coincidental."
Answer: Passive radar only records reflections and their shape and trail. Metabunk confirmed that passive radar can display reflections, such as those from the ISS and its flight path.
Metabunk comment: "Great! I was hoping someone knew how it all works! So, if I understand correctly, a more likely candidate for the radar signal would be a satellite or a meteorite rather than an airplane or other local object?"
JG response: "Passive radar has been used successfully for many years, including for detecting meteoroids. Thanks to these years of observation and analysis, the typical radar reflections from satellites, aircraft, and meteoroids are well documented and easily recognizable. However, the observed phenomenon bears no resemblance to the known signatures of these objects."
Metabunk comment: "Do people actually call these displays 'passive radar' even though they are not radar and no direction finding or distance measurement takes place?" It looks like nothing more than the signal's spectrum, presumably from an SDR. Why call it 'radar'?"
JG response: GRAVES transmits a signal 24/7 on the 143.050 MHz frequency. When an object that can produce a reflection crosses this transmission signal, the reflection is displayed on the passive radar."
Metabunk comment: "I see another example of simple logic here:
This antenna and software-defined radio (SDR) can be used for passive radar. I use this antenna and SDR. Therefore, I am doing passive radar. That is my understanding as well." You are looking at a waterfall diagram that shows signal strength and frequency over time. Yet, you seem to believe that you are looking at an actual image of the sky as if it had been captured by a camera. I hope I'm misunderstanding something, because basing your "investigation" on that would be a gross error.
JG's answer: Passive radar with an SDR only responds to reflections from objects crossing the GRAVES transmission beam.
Metabunk comment: "Yes, technically, it's not radar, but people do it anyway. That's life and practicality. I think 'passively recording a radio reflection from a distant radio transmitter that happens to be a radar' would be a more accurate term—but not exactly. True passive radar could use multiple receivers for triangulation, but it cannot control the transmission pulses like the SDR-based kits you mention.
JG response: Passive radar is real radar! It is particularly popular with militaries worldwide. Hensoldt, one of the market leaders in passive radar, is based in Germany. Using three receivers and antennas for triangulation would allow for the capture of more information, such as speed and direction.
Metabunk comment: "You're not suggesting that a simple spectrum diagram was 'back-engineered' to create a UFO story, are you? Who would do such a thing?"
JG response: Such a suspicion is completely unfounded. There is a credible eyewitness account, and the passive radar signal was discovered only during a later review of the recorded signals."
Metabunk comment: "Well, that's certainly not unusual. To be fair, though, it's entirely plausible that the author of the article simply didn't understand all the technical details Mr. Garcia explained. Many articles on websites dealing with 'science news' give this impression. Not every journalist has studied physics."
JG response: "That's correct. Since passive radar is a technically complex topic, many people quickly lose interest when the details become too technical. Therefore, only a brief, understandable overview was provided."
Metabunk comment: "The appearance of the light phenomenon is highly unusual and does not match any known UFO stimulus." So, is it not a UFO? Or is it an unknown UFO? The world's first UFO?"
JG response: In my opinion, this phenomenon has nothing to do with UFOs in the strict sense and certainly nothing to do with aliens. For me, it is a phenomenon that we have not yet been able to explain.
In a recent discussion between the two authors of this article, we talked about the possible number of objects observed, among other things. In connection with the two "points" preceding the phenomenon, two scenarios were considered based on the passive radar signal.
One scenario is that it was a single object that initially remained stationary for a short time after appearing. Then, it moved in a slight arc, stopped briefly again, and finally disappeared. The short dwell time in each case produced a stronger reflection, while the movement left only a faint trail.
Alternatively, there could have been two objects connected in some way.
Taking into account the witness's visual observation, we currently assume there were three separate objects.
Conclusion:
To be honest, we were surprised by the worldwide response. From our perspective, this is essentially just a case of a witness observing an unusual celestial phenomenon and, figuratively speaking, someone taking a photo of it. Most people did not interpret the event as an extraterrestrial spacecraft but rather as a unique phenomenon detected for the first time using private passive radar.
Therefore, the real trigger for the widespread attention was not so much the phenomenon itself but rather the fact that a private individual was able to monitor the sky using passive radar technology and record something unusual in the process.
If you are interested in your own passive radar system, please contact the GEP.
© Society for the Investigation of the UFO Phenomenon, GEP, original title :
Weltweit bislang einmaliges Ereignis - Passivradarsignal bestätigt UFO-Sichtung