Costa Rica.Lake Cote · IGN aerial photo

On September 4, 1971, around 08:25, an aircraft of Costa Rica's National Geographic Institute (IGN) was flying at about 10,000 feet (near 3,000 meters) over Lago de Cote, in the Arenal-Tilarán region, carrying out an aerial photogrammetric survey tied to the studies for the Costa Rican Electricity Institute's (ICE) Arenal hydroelectric project. The IGN's mapping camera (a large-format system producing 23×23 cm negatives at regular automatic intervals) recorded the terrain frame by frame for the map survey.

In one of those negatives, over the lake surface, a circular object of metallic appearance appears, its diameter, estimated by photogrammetric scale, put at some tens of meters (popular references often cite up to around 100 meters). The object shows a disc shape with a defined edge and a brightness consistent with a reflective surface. This was an automatic camera firing at fixed intervals during a routine state operation: no one was looking for an object, and the negative became part of an institutional sequence with chain of custody.

Dr. Richard F. Haines, a retired NASA-Ames scientist, and Jacques Vallée analyzed the case in two articles in the Journal of Scientific Exploration. The first (1989) worked from a second-generation negative and concluded that the image showed an opaque, unidentified aerial object at a maximum distance of 10,000 feet, with no visible means of lift or propulsion and no sign of double exposure or fabrication; since no shadow is visible on the lake, the authors suggested the object was at or very near the water surface. A reviewer of the article proposed a weighty mundane explanation: that the oval was an artifact of the film support, a pressure mark, that is, a deformation or dent in the film able to produce a blotch perceived as a solid object, an argument he based on inconsistent shadow patterns. The authors acknowledged that settling it required the original negative. They got it: through Peter Sturrock, Vallée and Ricardo Vílchez, they received frames 299, 300 and 301 of the original black-and-white negative on February 11, 1990, and published the result that same year. According to their note, the film plane was flat on all three frames, 'with absolutely no protrusions or depressions anywhere', so the reviewer's objection was left unsupported; there were small developer stains on frames 299 and 301, affecting only the emulsion's reflectivity and not its transmissivity, and none on frame 300; three thin parallel scratches, typical of heavily handled film, ran through the disc image; and nothing indicated a double exposure, reflection, paste-up or any other kind of hoax. They also described a microstructure of light streaks all oriented in the same oblique direction, whose origin they said they did not understand. Neither the object nor any disturbance of the water appeared on the adjacent frames, so it must have entered and left the field within about 20 seconds: if it flew at ground level, that would imply between about 1,425 and 1,988 miles per hour, figures that depend entirely on that distance assumption. They concluded that the disc was 'certainly anomalous. While it may not be inexplicable, it is at least unidentified.' The limit of that result should be recorded: it was a visual and magnified inspection by the authors themselves, in a four-page note, not an independent laboratory examination.

Fifty-five years on, the file gained names and detail. The camera operator was the cartographer Sergio Loaiza, aboard a twin-engine Aero Commander F680, and the frame is identified as 'Frame 300' of the survey roll; the original negative remains in the custody of the Costa Rican national archive. One detail of the account itself reinforces how unsought the image was: the crew noticed nothing during the flight, and the disc appeared only when the negatives were developed.

In 2022 the most detailed digital copy available was produced. Esteban Carranza, a Costa Rican attorney and researcher, inherited from an uncle a contact copy of the negative (obtained from the IGN in the late 1970s or early 1980s) and sent it to a laboratory in Kansas, where it was scanned on a Heidelberg Tango drum scanner, an instrument used for archival and fine-art reproduction; the result was published openly. It is worth being precise about what that scan settles and what it does not, because it is easy to overread: it was made from a copy, not from the original negative. Any defect of the original support reproduces faithfully in a contact copy and in any scan of it, at whatever resolution, and conversely a scan of the copy can say nothing new about the relief of the original film. The scan therefore delivers a far better view of the same information, not new information about the support. The only published inspection of the original negative is still Haines and Vallée's in 1990; an independent examination of that negative, which remains in the Costa Rican archive, would be the missing step.

On 4 September 2026, on the exact 55th anniversary of the exposure, the documentary 'The Cote Photo', by Adam Pillon and Megan Woomer (Great Films LLC), premiered on Apple TV and Prime Video. Its novelty is Loaiza speaking on camera in detail for the first time, about both the 1971 flight and experiences with anomalous phenomena that he places in years before that flight.

The photo comes from a governmental mapping camera, firing automatically during a routine operation, with institutional chain of custody. There was no witness: no one on board saw the object, so no testimony could have biased the report, but none corroborates it either.

Even so, a photo of known provenance is not a proven photo. Haines and Vallée's analysis does not authenticate the object as a craft: it concludes that it is anomalous and unidentified, not that it is inexplicable. What it did do was put the main mundane explanation to the test: they examined the original negative and found neither the physical deformation the reviewer proposed, nor developer stains on frame 300, nor any trace of montage or double exposure. That refutes the reviewer's specific version, but it does not close the emulsion-artifact hypothesis: a purely sensitometric pressure mark leaves no relief to look for, and the inspection was carried out by the authors themselves, not by an independent laboratory. Added to that, the oblique microstructure they themselves describe has no explanation. Nor has any concrete prosaic explanation prevailed: no one has identified a known object consistent with the image. The case therefore has a known provenance and chain of custody, and is genuinely indeterminate as to the nature of what was photographed.

The 2022 scan and the 2026 documentary contribute different things. The scan was made from a copy: it adds nothing to what the 1990 inspection of the original negative already said. It improves the viewing and nothing more, and it is worth recording that before the phrase 'grain-level scan' gets read as if it had closed the debate.

The documentary raises something more delicate. That Loaiza describes anomalous experiences predating 1971 opens no new mechanism: the camera fired by itself at a fixed interval, and the routes by which an interested operator could have fabricated the image (montage, double exposure, manipulation) are precisely the ones Haines and Vallée examined and ruled out. What it does introduce is a motive. The camera fired by itself, but it is no longer accurate that no observer had a prior interest in the subject.