Adak, AlaskaSeptember 1950

On September 11, 1950, a Coast Guard photographer aboard the USCGC Northwind, stationed about 40 miles north of Adak in the Aleutian Islands, took four photographs of a total solar eclipse. The photographer used a Speed Graphic camera with a coated lens set at f/4.7 and exposed the film at 1/100th of a second with a Wratten "A" filter. He noticed nothing unusual while taking the pictures at approximately 4:45 p.m. (local time).

Two years after the photographs were developed, the photographer examined the negatives and noticed additional unidentified images appearing to the right of the eclipse images on each frame. These mystery images varied in size, shape, and distance from the main eclipse image. The photographer forwarded the negatives to the U.S. Coast Guard, which then submitted them to the Air Force for expert analysis in July 1952.

Air Force photo specialists examined the negatives and determined the most probable explanation. When a bright object like the sun is photographed with exposure settings that are too high (excessive for the brightness of the subject), optical flare appears in the camera lens. The analysts found that the negatives showed considerable halation, a blurring halo effect around the sun images caused by overexposure. They reproduced similar flare spots in the laboratory by pointing the same camera model at the sun with similar settings. Any movement of the camera or adjustments to lens filters caused the flare spots to shift position on the film, matching the behavior of the unidentified images on the original negatives. The specialists concluded that the spots in question were nothing more than flare artifacts resulting from excessive exposure for an object as bright as the sun.

The full case file, consisting of 15 pages as held by the National Archives, is reproduced below.