CHATEAUGIRON (35) 06.09.2023

On 6 September 2023 at about 07:40, T1 and spouse T2 saw a UAP through an upstairs roof window at their home in Châteaugiron (35). T1 described a double brown rectangle; T2 described 2 joined ellipses, one with a hole through which the sky was visible (their sketches are in Annex 1). It moved slowly and silently from north-northwest to south-southwest for approximately 3 minutes. T1 photographed it receding (Annex 2). The witnesses submitted separate technical questionnaires in September and November 2023. A field investigation on 25 November included cognitive interviews with both, which confirmed their questionnaire information without contradiction. Given its shape, GEIPAN investigated only 2 balloons carried together by the wind. One horizontal and one vertical ellipse could be 2 interlinked O-shaped balloons of the kind commonly used for birthdays and other celebrations; it found T2's drawing particularly suggestive. The dark-brown colour was not decisive, as balloons can be any colour. The witnesses estimated the apparent size as 3 cm at arm's length. A test of their estimates of the Moon's angular size indicated overestimation by at least a factor of 2. Using 1.5 cm instead gave a possible size of about 1 m at 53 m distance, plausible for 2 balloons. A straight path with oscillations also fitted balloons, whose asymmetric combined shape could be unstable. The nearest weather station, Rennes–Saint-Jacques, recorded a light north-northwest wind that GEIPAN considered consistent with the reported movement. The slightly more distant Arbrissel station recorded a west wind (Annex 3, with times in UTC). Elevation itself was not decisive, but its constancy fitted a straight path parallel to the ground. Steady, relatively low apparent speed fitted a passive object carried by wind. GEIPAN assessed the evidence as good, with 2 witnesses, a photograph and field interviews, although the photograph could not be usefully analysed. Despite the unusual appearance, it favoured 2 interlinked windborne balloons, while retaining uncertainty over speed and exact direction. It classified the case B: probable balloons. GEIPAN defines evidential support as the amount of information collected for an account that is considered reliable and objectively established.