The Lago de Coté UFO Photograph

Briefing

At approximately 08:25 (EDT) on the fourth of September 1971, a Costa Rican government aircraft mapping Lago de Coté for terrain and hydroelectric study work in the Arenal region automatically photographed an unidentified, opaque aerial object over the lake while flying at about 10,000 feet [1]. The flight was a routine aerial-mapping survey; the automatic survey camera exposed frames at fixed intervals, and the object appears on only one frame, set against the uniformly dark water [1][2]. No member of the crew reported seeing anything unusual at the time [4].

Sequence of events

• The survey was undertaken in connection with terrain and hydroelectric study work in the Arenal region. The crew comprised four people — an aerial-photography specialist, a geographer, a topographer and the pilot — none of whom reported seeing anything unusual [4].
• The camera was a Wild RMK 15/23 aerial mapping camera loaded with ASA 80 film (Kodak air-safety film type 3665), producing a large negative of around ten inches [2][3].
• At approximately 08:25 (EDT), flying at about 10,000 feet, the automatic camera exposed the frame showing the disc-shaped object over the lake [1].
• The object is reported to appear on frame number 300 of the survey run, set against the uniformly dark water; it appears on only that single frame [1][2][3].

Documentary record

The principal source is the peer-reviewed paper “Photo Analysis of an Aerial Disc Over Costa Rica” by Dr Richard F. Haines, a former NASA research scientist, and Dr Jacques F. Vallée, published in the Journal of Scientific Exploration, Vol. 3, No. 2 (1989), pp. 113–131, with a follow-up (“New Evidence”) in Vol. 4, No. 1 (1990) [1]. Analysing second-generation black-and-white negative and positive transparencies, the authors concluded that “an unidentified, opaque, aerial object was captured on film at a maximum distance of 10,000 feet. There are no visible means of lift or propulsion and no surface markings other than dark regions that appear to be nonrandom… There is no indication that the image is the product of a double exposure or a deliberate fabrication” [1][2]. They noted that the object casts no visible shadow on the lake surface, consistent with it being at or near the water surface, and raised a fuzzy region on one side as a possible partial submersion or edge effect [2]. From the geometry the analysts derived a maximum possible diameter of roughly 683 feet, an upper bound assuming maximum distance [4].

The original negatives are held in Costa Rica’s National Archive, reported to be catalogued under signatura NP-002544 and to contain five negatives and three positives from the survey run, including the frame showing the object [3]. The photograph is held on Wikimedia Commons as File:Cote_ufo.jpg, with rights attributed to the Instituto Geográfico Nacional de Costa Rica under an attribution-only licence — reusable with attribution, not public domain [5].

Open questions

1. The primary analysis does not establish what the object is — only that it is opaque, real to the film, and not an obvious fake [1].
2. The exact distance, and therefore the true size, is unresolved; 10,000 feet is a maximum, so the object could be far smaller and closer [1][4].
3. No witness saw the object, so there is no firsthand sighting testimony to corroborate the film [1][4].
4. Whether the original first-generation negative has ever been examined under glancing-light illumination — to rule out a physical film or optics artefact — is not resolved in the available sources; Haines and Vallée themselves recommended such an inspection [2].
5. A caveat within the analysts’ own work flagged that the image “is more likely to be an artifact such as a pressure mark than a photographic image of a physical object” [2]. Later commentators have proposed alternatives: the Rocky Mountain Paranormal Research Society (2013) argued for an internal lens reflection arising from a specific combination of camera system, plane angle and sun position; a “chipped glass” hypothesis (2014) proposes a stone-chip on the camera glass producing a bullseye-like reflection; and a “boat wake” explanation, attributed to commentator Michael Ian Black, attributes the bright areas to sunlight on waves [2][3].

Status

This file is CONFIDENTIAL — admitted to the archive on the strength of an official government survey photograph and a peer-reviewed analysis that found no evidence of fabrication [1][5]. That analysis is explicit that the object is unidentified, and the same authors recorded a caveat that the image may instead be a camera artefact; this file therefore records a documented, unexplained photograph, not a confirmed craft [1][2]. The image is widely described as a “Daylight Disc” in the Hynek classification — a metallic or whitish object seen by day — and local farmers were said to have previously reported strange objects moving on or just below the lake surface, though neither claim is independently verified here [4]. Crew names commonly cited in secondary accounts could not be confirmed from a primary source in this pass and are omitted. Updates pending any glancing-light re-examination of the original negative.

References

1. Haines, R. F. & Vallée, J. F. (1989). “Photo Analysis of an Aerial Disc Over Costa Rica,” Journal of Scientific Exploration, Vol. 3, No. 2, pp. 113–131 (follow-up Vol. 4, No. 1, 1990). Hosted by NICAP.
2. Gross, Patrick. “UFOs at close sight: the Lago de Cote photograph, 1971”. ufologie.net.
3. Metabunk. “1971 Lake Cote / Lago de Cote UFO Aerial Photo”.
4. Think AboutIt Docs. “1971: Lago de Cote Photograph”.
5. File:Cote ufo.jpg. Wikimedia Commons / Instituto Geográfico Nacional de Costa Rica.