Sighting in Boulogne-Billancourt, September 29, 2012

Around 3 p.m., a witness looking out of a window noticed a small white light high in the sky, flashing on and off. After about a minute, the point of light stopped, then resumed its course, this time without flashing. The witness was facing south and saw it move toward the east. These details were gathered by telephone.

Ground weather readings showed a northwest wind at 2 p.m. and a north wind at 3 p.m., so the object could not have been carried by the wind at low altitude. However, Météo-France releases a weather balloon from Trappes every day, around 2 p.m. local time, one hour before the sighting. The data show a weak northwest wind at the surface, turning stronger and westerly from about 2,800 m, then returning to northwest higher up. Since the winds at altitude blew toward the east, this balloon accounts well for the observation. The flashing is explained by the rotation of the balloon or of reflectors attached to it.

GEIPAN classified the case as A: the witness had seen a Météo-France weather balloon launched from Trappes at 2 p.m.