Sighting in Évry-Courcouronnes, June 28, 2023

At around 7 p.m., the witness was inside a stadium when they noticed an object moving across the sky. They immediately filmed it for about four minutes. The object was round and black, with no halo or distinctive structure; the witness thought it looked metallic, though this is not visible on the video. It seemed to be flying low, at about the height of one of the stadium floodlights, and moved slowly and without any noise. After a few minutes it drifted away, climbing until it disappeared. According to the witness, its path was straight and rising, with apparently random movements at high altitude.

There was only one witness. Using landmarks in the video and the diagrams the witness supplied, the GEIPAN reconstructed a movement from east to west, with some margin of uncertainty. The case was rated as having good consistency.

The investigation pursued the hypothesis of a helium balloon, probably made of Mylar: its round shape, plausible black color, metallic look, and slow, rising movement all fit. The wind, light and mostly from the north-east, matches the slow pace and the direction observed. The shifts in course at altitude are explained by more irregular winds, although the weather data cannot demonstrate this. The witness had considered a balloon but ruled it out for three reasons: the object seemed solid, it changed direction, and no string was visible. The GEIPAN answers that the impression of volume comes from the color, the metallic look and the perfectly round shape, that the changes of direction result from the winds, and that a string may be missing, detached or cut. The balloon's origin was not determined, but many schools surround the area to the north and east, and it was the end-of-school-year festivities period. The case is classified A: a balloon.