Sighting in Châteaugiron, September 6, 2023

At about 7:40 a.m., two witnesses, a couple, were looking out of a roof window on the upper floor of their home when they noticed a dark phenomenon in the sky. One described it as a brown double rectangle. The other saw two ellipses joined together, one of them with a hole through which the sky was visible. It moved slowly and silently from the north-northwest toward the south-southwest. The observation lasted about three minutes. One of the witnesses managed to photograph it as it moved away. At arm's length, the witnesses estimated its size at about 3 cm.

Each witness filled out a technical questionnaire for GEIPAN, in September and November 2023. A field investigation with a cognitive interview of each witness took place on 25 November 2023. Their accounts matched, with no contradiction.

The investigation considered only one hypothesis: two interlaced balloons carried by the wind. "O"-shaped balloons, common at parties, fit one witness's drawing. The color is not decisive. A test using the angular size of the Moon showed that the apparent size had been overestimated by a factor of at least two. At 1.5 cm, this gives roughly 1 meter at a distance of 53 m, which is plausible for two balloons. The straight trajectory with oscillations, the constant elevation and the steady, low speed are all consistent with a passive object drifting in the wind. The nearest weather station reported a light north-northwest wind, and the Arbrissel station a west wind. The photo could not be analyzed. Some uncertainty remains about the exact speed and direction of travel. GEIPAN classified the case as B: probable observation of balloons.