Leadville, ColoradoJune 1960

On the morning of June 4, 1960, a Canadian tourist visiting Leadville, Colorado witnessed something unusual in the sky. Between 0620 and 0730 (6:20 a.m. and 7:30 a.m.), the observer reported seeing an object flying very high and very fast. The witness described it as resembling a pair of cymbals rapidly oscillating together, extremely bright and almost luminous. The object appeared to dive and then climb across his field of view. A second object then appeared, following the same path, and the witness dashed inside to grab his camera and photograph it.

The photograph, taken with a Zeiss Contessa camera at a shutter speed of 1/500 of a second, showed a disk-like object with what appeared to be trails or streaks. The image was forwarded through Canadian military intelligence to the U.S. Air Force's Aerospace Technical Intelligence Center (ATIC) for analysis. The witness reported that the object was about three times the size of a matchhead at arm's length, made no sound, and was visible for only 1 to 3 seconds.

Air Force analysts examined the photograph and calculated that if the object truly traveled across the camera's field of view in the time captured by the shutter, its speed would have been impossibly fast, exceeding 7 million knots at a reasonable distance. The analysts concluded that the twin disk-like shape in the photograph was most likely a lenticular cloud, and that the apparent trails were caused by streaks on glass or lens aberration (distortion caused by imperfect optics), not by the object itself. They noted that the witness had not followed the object with the camera during the shot, and that the photo appeared to have been taken level with the horizon rather than aimed at where the object supposedly was.

The Air Force determined there were no other witnesses and that the photograph had not been taken through a window. However, they suggested the image could have resulted from reflections or glass distortion if taken near a window or building.

The file shows that the Air Force's final evaluation was that the object was probably a lenticular cloud. The full case file is reproduced below as held by the National Archives, comprising 12 pages.