PARIS (75) 25.08.2019

On the morning of 25/08/2019 in Paris, a couple observed, from their terrace, for almost 30 minutes a luminous phenomenon in the sky. The witnesses followed the evolution of the UAP with a telescope, binoculars and took pictures and videos with their mobile phones. The case was supported by these two testimonies (see the investigation report). According to the GEIPAN criteria, the evidential quality* of the case is very good (two witnesses who have carefully described their observation, presence of photos and videos of the UAP). * Evidential quality is the amount of information considered reliable, collected for testimony. GEIPAN favors a cluster of connected helium-filled Mylar balloons. Its slow, steady ascent along an arc can be explained by light winds whose direction varied greatly between 250 and 2,750 m. By reaching a sufficient altitude, the pressure exerted by the expanded helium could cause the balloons to explode, which can explain the sudden disappearance of the UAP. The elements for this hypothesis are: - shape of the UAP seen at the telescope, resembling an assembly of balloons, - the UAP shine seen with the naked eye, conforming to that of Mylar balloons strongly reflecting the brightness of the sun, - the UAP path, in line with low and changing winds depending on altitude, - sudden disappearance may have occurred by bursting balloons arriving at a certain altitude (which theoretically would need to be high) although there is no data to demonstrate this. Unfortunately, photos and videos are of limited use (fluctuating image sharpness and loss of focus). The smartphones used to make them are not suitable for properly focusing an object of small angular size and the use of zoom only makes the loss of sharpness worse. No corroboration of such a balloon release on that day was identified, either in media sources or on social media platforms. The investigation characterized the UAP, to propose a coherent hypothesis from the testimony, but without being able to provide any formal evidence. This case is classified by GEIPAN in category "B": likely observation of an assembly of Mylar balloons.