Sighting in Gourbit, June 28, 2011

A witness sent GEIPAN a series of photographs in which they had found "strange elements". Nothing unusual had been noticed when the pictures were taken. Wanting to understand what showed up in the images, the witness took another photograph under the same conditions the next day, and the same phenomenon appeared again.

The investigation found that the effect came from reflections inside the camera's optics, which take the form of "caustics", a family of surfaces in optics. Whether a camera is prone to this depends on how its optical blocks are arranged. The five pictures, taken in Ariège, were made in highly favourable conditions: a dark landscape with a few bright light sources, giving strong contrast, further increased by long exposures of 23 to 35 seconds.

The quality of the images led GEIPAN to open the case as a concrete illustration of a misidentification caused by an optical phenomenon, linked to the use of a digital camera under particular conditions. The case was classified A: identified.