Cergy 1991, circular object with flashing lights

Summary

At dusk in September 1991, a witness in Cergy spotted a circular object estimated at 20 to 40 meters in diameter at an altitude of 100 to 200 meters. It emitted a steady rumbling sound and displayed flashing multicolored lights along its perimeter. It moved slowly in a straight line from northeast to southwest and, after 3 to 4 minutes, faded into the sky without changing direction. The witness filed a police report, but no other testimonies emerged. In 2010 they clarified the sighting occurred in September 1991 and attached a trajectory sketch and a drawing of the object. The elapsed time makes any supplementary physical investigation difficult.