Circular UFO sighted in Cergy in 1991

Summary

A witness reported seeing a circular object measuring between 20 and 40 meters in size during the twilight in September 1991. The object emitted a constant humming sound and displayed flashing lights of various colors around its perimeter. It was moving slowly along a straight trajectory from northeast to southwest, at an altitude between 100 and 200 meters. The phenomenon lasted between 3 and 4 minutes, and the object disappeared without changing direction, blending into the sky. The witness filed a report with the local police, but no other testimonies were collected. Due to the time elapsed, a physical investigation became difficult. In 2010, the witness clarified that the observation took place in September 1991 and provided documents on the trajectory and a schematic drawing of the object.