S of Caja Marca, Peru, October 1957October 1957

In October 1957, a weather observer at a meteorological station south of Cajamarca, Peru reported seeing a bright, gleaming white object on multiple occasions. The observer used a Zeiss-Recording-Theodolite (a precision instrument for measuring angles in the sky) to carefully track the object's position, noting its azimuth (compass direction) and elevation (height above the horizon) at regular intervals.

The observer first spotted the object on October 26 while on an outing near Sunchubamba Lake. It remained visible for more than fifteen minutes and could be seen with the naked eye without binoculars. Over the following days, on October 28, 29, and November 8, the same object was observed again from the weather station at an altitude of 3,750 meters (about 12,300 feet). On November 8, the observer made precise measurements over several minutes as the object moved slowly across the sky, rising steadily in elevation while drifting slightly in azimuth. The visibility varied from fair to poor due to cloud cover, but the object was sometimes visible shining through the clouds.

The Air Force evaluation of this case concluded that the object was "probably astronomical." Specifically, the case file notes that the plotted positions matched almost exactly with the position of the planet Venus at the times the observations were made. The file also notes that while it is rare to see Venus in daylight, the precision instruments used by the trained weather observer made this observation possible. A newspaper astronomy article included in the case file describes Venus in November 1957 as "far brighter than any other star or planet seen in the night sky" and notes that "it can be observed long before the sky is dark" and "even in broad daylight."

The complete case file, including observation logs and supplementary materials, is reproduced below as held by the National Archives, consisting of 7 pages.