Within Hessdalen
The Blind Spots in Hessdalen's Sky Watch
The station's limited view, hills and sensitivity limits made its records useful but not a full census of every light in the valley.
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- Field of view and blocked horizons
- Missed faint brief or hidden events
- Why long duration is not full coverage
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Introduction
The Hessdalen Automatic Measurement Station (AMS) is often presented as one of the longest-running automated sky-monitoring projects associated with unexplained aerial lights. Its records are valuable precisely because they were collected continuously over many years. Yet the station was never intended, and never capable, of providing a complete census of every light event in the valley. The combination of mountainous terrain, a fixed observing position, camera sensitivity limits, software thresholds, maintenance constraints and incomplete spatial coverage meant that some events were inevitably missed. The Hessdalen project itself repeatedly acknowledged these limitations and proposed additional cameras and instruments as a remedy. The lesson for automated UFO and UAP detection is important: long duration does not automatically equal full coverage. A detector can operate for decades and still observe only a subset of what occurs within its target area. [Hessdalen Project]old.hessdalen.orgHessdal article2000.shtmlHessdalen ProjectProject Hessdalen18 Mar 1983 — Hessdalen AMS (Automatic Measurement Station) was installed in Hessdalen on 7th August 19…
Field of View and Blocked Horizons
The most obvious limitation of the Hessdalen station was geography. The AMS was installed on the side of Rognefjell mountain and was aimed primarily westward toward the mountain Finnsåhøgda. This placement provided a useful observing corridor but did not give the system a view of the entire valley. Project Hessdalen’s own documentation explicitly noted that only part of the valley was being covered and that more cameras were needed to observe additional areas. [Hessdalen Project]old.hessdalen.orgHessdal article2000.shtmlHessdalen ProjectProject Hessdalen18 Mar 1983 — Hessdalen AMS (Automatic Measurement Station) was installed in Hessdalen on 7th August 19…
This matters because the reported Hessdalen lights have appeared across a valley roughly 12 kilometres long and at varying altitudes. Some reports describe lights near the horizon, others high above ridges, and others appearing in different sectors of the valley. A fixed camera looking in one direction inevitably leaves blind zones behind hills, ridgelines and terrain features. Even when a phenomenon occurs within the broader Hessdalen region, it may never enter the monitored viewing sector. [Wikipedia]WikipediaHessdalen lightsAugust 8, 2004 — The Hessdalen lights are unidentified lights which have been observed in a 12-kilometre-long (7.5 mi) stretch of the Hes…
The later AMS configuration improved coverage by adding multiple cameras facing different directions and placing one camera at a second location about 171 metres away. Nevertheless, these additions expanded the monitored volume rather than eliminating all blind spots. The system remained a local observatory, not a valley-wide sensor network. [Hessdalen Project]old.hessdalen.orgHessdalen ProjectProject Hessdalen - AMS21 Jan 2019 — There are three CCD cameras which transmit live TV all the time (24/7). Two of thos…
Missed Faint, Brief or Hidden Events
Coverage was constrained not only by where the cameras looked but also by what they could detect.
The first AMS relied on software that compared successive camera images and triggered an alarm only when a sufficiently large and sufficiently bright change appeared in the field of view. Project documentation states that detection depended on both intensity and apparent motion, and that these thresholds were adjustable in software. Importantly, the project acknowledged that not all phenomena were being detected at the chosen sensitivity settings. Observers reported events that the station failed to record. [Hessdalen Project]old.hessdalen.orgHessdal article2000.shtmlHessdalen ProjectProject Hessdalen18 Mar 1983 — Hessdalen AMS (Automatic Measurement Station) was installed in Hessdalen on 7th August 19…
This created a classic detection trade-off. If sensitivity was set too high, the station produced excessive false alarms from ordinary lights, reflections, atmospheric effects or image noise. If sensitivity was reduced to keep the system manageable, dimmer or more subtle events could be missed. Project Hessdalen specifically stated that a second camera would allow sensitivity to be increased because cross-checking between cameras would reduce false detections. [Hessdalen Project]old.hessdalen.orgHessdal article2000.shtmlHessdalen ProjectProject Hessdalen18 Mar 1983 — Hessdalen AMS (Automatic Measurement Station) was installed in Hessdalen on 7th August 19…
Short-duration events posed another challenge. The original system analysed images at intervals of roughly one second or less and reacted when a significant change appeared. Extremely brief flashes, faint transients or events occurring between sampling moments could potentially escape detection. Likewise, phenomena obscured by weather, cloud, precipitation or terrain would never be visible to the camera regardless of their brightness. [Hessdalen Project]old.hessdalen.orgHessdalen ProjectProject Hessdalen - AMS28 Dec 2019 — The station consisted of one black-and-white CCD-camera, connected to a SGI-compute…
The nature of the reported lights amplified this problem. Accounts describe a wide range of behaviours, from long-lasting luminous objects to rapid spark-like flashes. A detection system optimised for one class of event may be less effective for another. [NaturPhilosophie]naturphilosophie.co.ukNatur Philosophie The Hessdalen Light Phenomenon, NorwayThe Hessdalen Light Phenomenon, Norway - NaturPhilosophieMay 7, 2023 — 7 May 2023 — The Hessdalen light phenomenon starte…
Why One Station Could Not Measure Everything
A single observation point also limits what can be learned about an event that is detected.
Project documentation from the early AMS period emphasised that one camera could not reliably determine the distance to a target. Without distance information, apparent brightness, size and speed become difficult to interpret. This was one reason the project later introduced multiple cameras separated by a baseline, allowing triangulation of some observations. [Hessdalen Project]old.hessdalen.orgHessdal article2000.shtmlHessdalen ProjectProject Hessdalen18 Mar 1983 — Hessdalen AMS (Automatic Measurement Station) was installed in Hessdalen on 7th August 19…
The inability to determine distance creates a hidden completeness problem. Even when a light is recorded, researchers may not know whether it was a small nearby object or a larger distant one. Two apparently similar detections could represent very different physical events. Thus the station’s catalogue was never a complete inventory of objectively characterised phenomena; it was a collection of events filtered through the geometry and capabilities of the observing system. [Hessdalen Project+2Hessdalen Project]old.hessdalen.orgHessdal article2000.shtmlHessdalen ProjectProject Hessdalen18 Mar 1983 — Hessdalen AMS (Automatic Measurement Station) was installed in Hessdalen on 7th August 19…
The station also measured only a limited set of parameters. Cameras, a magnetometer and later additional instruments could capture some aspects of an event, but not every relevant physical characteristic. The AMS itself has been described as measuring a restricted number of parameters and therefore being unable to explain all recorded observations. [Wikipedia]WikipediaHessdalen AMSHessdalen AMS
Long Duration Is Not Full Coverage
One reason Hessdalen remains important is that it demonstrates both the strengths and weaknesses of persistent monitoring.
Running continuously for years solved a problem that short expeditions could not solve: rare events had a greater chance of being captured. The station produced statistics on seasonal and hourly patterns and accumulated a large archive of detections. Yet even those long-term records contain gaps. Published analyses note incomplete years in the dataset, while project descriptions repeatedly discuss the need for additional sensors, more cameras and broader coverage. [ResearchGate]researchgate.netA long-term scientific survey of the Hessdalen phenomenonTemporal statistics of luminous events in Hessdalen obtained by the…
The key lesson for automated UFO and UAP observatories is therefore methodological rather than mysterious. A fixed detector is never a neutral window onto everything occurring in the sky. It sees only what enters its field of view, exceeds its detection thresholds, survives weather and terrain masking, and occurs while the system is operating as intended. Hessdalen’s AMS generated some of the best long-term data available from a reported aerial-light hotspot, but its own operators recognised that the station observed only part of the environment it was designed to watch. [Hessdalen Project+2Hessdalen Project]old.hessdalen.orgHessdal article2000.shtmlHessdalen ProjectProject Hessdalen18 Mar 1983 — Hessdalen AMS (Automatic Measurement Station) was installed in Hessdalen on 7th August 19…
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Endnotes
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Source: old.hessdalen.org
Title: Hessdal article2000.shtml
Link: https://old.hessdalen.org/reports/Hessdal-article2000.shtmlSource snippet
Hessdalen ProjectProject Hessdalen18 Mar 1983 — Hessdalen AMS (Automatic Measurement Station) was installed in Hessdalen on 7th August 19...
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Source: old.hessdalen.org
Link: https://old.hessdalen.org/station/Source snippet
Hessdalen ProjectProject Hessdalen - AMS21 Jan 2019 — There are three CCD cameras which transmit live TV all the time (24/7). Two of thos...
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Source: Wikipedia
Title: Hessdalen lights
Link: https://en.wikipedia.org/wiki/Hessdalen_lightsSource snippet
August 8, 2004 — The Hessdalen lights are unidentified lights which have been observed in a 12-kilometre-long (7.5 mi) stretch of the Hes...
Published: August 8, 2004
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Source: old.hessdalen.org
Title: Project Automatic Measurement Station (AMS)
Link: https://old.hessdalen.org/station/second.shtmlSource snippet
If a light show up in both cameras, all videorecorders startet, direction measured...Read more...
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Source: old.hessdalen.org
Link: https://old.hessdalen.org/station/first.shtmlSource snippet
Hessdalen ProjectProject Hessdalen - AMS28 Dec 2019 — The station consisted of one black-and-white CCD-camera, connected to a SGI-compute...
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Source: Wikipedia
Title: Hessdalen AMS
Link: https://en.wikipedia.org/wiki/Hessdalen_AMS -
Source: researchgate.net
Link: https://www.researchgate.net/publication/228609015_A_long-term_scientific_survey_of_the_Hessdalen_phenomenonSource snippet
A long-term scientific survey of the Hessdalen phenomenonTemporal statistics of luminous events in Hessdalen obtained by the...
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Source: researchgate.net
Title: 228559449 The EMBLA 2000 Mission in Hessdalen
Link: https://www.researchgate.net/publication/228559449_The_EMBLA_2000_Mission_in_HessdalenSource snippet
(PDF) The EMBLA 2000 Mission in HessdalenPDF | In August 2000 a team of italian physical scientists, working in collaboration with Norweg...
Published: August 2000
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Source: naturphilosophie.co.uk
Title: Natur Philosophie The Hessdalen Light Phenomenon, Norway
Link: https://naturphilosophie.co.uk/2023/05/07/identifying-the-unidentified-the-hessdalen-light-phenomenon-norway/Source snippet
The Hessdalen Light Phenomenon, Norway - NaturPhilosophieMay 7, 2023 — 7 May 2023 — The Hessdalen light phenomenon starte...
Published: May 7, 2023
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Source: wiki.bambulab.com
Link: https://wiki.bambulab.com/en/ams/maintenanceSource snippet
and How To guidesParts wear or faults are unavoidable during its long service. There are many guides here that could help people to do se...
Additional References
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Source: reddit.com
Link: https://www.reddit.com/r/genetec/comments/1sn6lb0/missing_green_event_highlights_in_timeline/Source snippet
Missing Green Event Highlights in Timeline: r/genetecFor some reason our cameras at one of our sites are missing the green highlights in...
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Source: societyforuapstudies.org
Link: https://www.societyforuapstudies.org/project-hessdalenSource snippet
Project HessdalenFifty-three light observations were made during the field investigation. You... An automatic measurement station was pu...
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Source: medium.com
Link: https://medium.com/%40krindiri/six-minds-one-valley-one-big-mistery-remote-viewing-the-famous-hessdalen-lights-bca46c64c9a8Source snippet
Remote Viewing the famous Hessdalen LightsSix independent viewers. One blind target. A Norwegian valley that has defied explanation for o...
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Source: facebook.com
Title: the hessdalen lights have stumped scientists for 40 yearsin a remote valley in n
Link: https://www.facebook.com/61583174895936/videos/the-hessdalen-lights-have-stumped-scientists-for-40-yearsin-a-remote-valley-in-n/1607905727171889/Source snippet
The Hessdalen Lights Have Stumped Scientists for 40 Years...May 2025, something moved through their camera field so fast it appeared in...
Published: May 2025
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Source: community.amplitude.com
Link: https://community.amplitude.com/data-instrumentation-57/amplitude-events-data-missing-4620Source snippet
amplitude.com[https://community.amplitude.com/data-instrumentati...No](https://community.amplitude.com/data-instrumentati...No) information is available for this page...
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Source: instagram.com
Title: The Norwegian Valley Where Strange Lights Have Glowed for Decades
Link: https://www.instagram.com/reel/DX7LS5SxHsV/?hl=en-gbSource snippet
Tucked into the quiet mountains of central Norway, there's a small valley called Hessdalen where something genuinely puzzling has been ha...
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Source: pubmed.ncbi.nlm.nih.gov
Link: https://pubmed.ncbi.nlm.nih.gov/42146727/Source snippet
Latency Measurements of Event Camerasby RV Chassagnol · 2025 · Cited by 1 — We describe such a solution and report pixel latency measurem...
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Source: youtube.com
Title: What are Mysterious Hessdalen Lights?
Link: https://www.youtube.com/watch?v=keDOI_nndVUSource snippet
The Hessdalen Lights Have Stumped Scientists for 40 Years - YouTube The Hessdalen Lights Have Stumped Scientists for 40 Years - YouTube...
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Source: facebook.com
Link: https://www.facebook.com/groups/388012498516204/posts/1169604847023628/Source snippet
Hessdalen light phenomenon in NorwayProject H essdalen ran a field investigation in 1984 and 1985, and are now running Hessdalen Automati...
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Source: community.synology.com
Link: https://community.synology.com/enu/forum/3/post/146175Source snippet
missing in Timeline - Surveillance9 Aug 2021 — I think there is possibility that your timeline filter might filter out the event. you cou...
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