O'Hara AFB, Ill, May 1959May 1959

In May 1959, a photographer at O'Hara Air Force Base in Chicago captured a photograph during an Armed Forces Day air show held on May 17. The photographer reported seeing a streak on the developed film that had not been visible to the naked eye during the event. The image was submitted to the U.S. Air Force's Project Blue Book investigation for analysis.

The Air Force's technical experts at the Aerospace Technical Intelligence Center examined the photograph and the film negative. The analysts concluded that the streak was a developing flaw created during the film processing stage, not a real object in the sky. The streak also did not extend to the border of the negative or appear on any other film, which supported the conclusion that it was a defect rather than an actual aircraft or aerial phenomenon.

The Air Force ultimately classified the case as unexplained due to insufficient data. The negative was returned to the photographer after analysis. The full case file, comprising 10 pages of correspondence, analysis, and technical evaluations, is reproduced below as held by the National Archives.