LIANCOURT (60) 18.04.2015

On Saturday 18 April 2015 at 23:45, a witness in his property watched for 2 minutes the movements of 2 luminous objects, white and red in the night sky. Both objects seem to be flying one behind the other. No particular noise was heard during the observation which the source says ended at 23:53, despite also giving 23:45 as the start and a 2-minute duration. The witness reported his observation to the gendarmerie by letter. The investigation will establish that no particular weather phenomena took place that evening, no fireworks were organized by town halls in the area, no military training flights took place. Local inquiries did not allow for further observation testimonies. The observation of white and red lights crossing the sky in a few minutes, a weekend night, strongly suggests sky lanterns, probably released nearby at the end of a private party. The movement is observed from the northwest (Bailleval) westward (see carto), which is consistent with the northeasterly wind reported at Creil as 20–30 km (the source omits “per hour”; see the Météociel record for that day). Some elements of the observation report are, however, not well suited to the hypothesis of objects carried by a northeasterly wind: -the objects stop above the marsh: this fact requires that the wind weakens at this place, or changes direction: this remains possible given the particular relief of this particularly humid valley. -One of the objects goes up towards Ars, due west: this description can correspond to the progressive extinction of the lantern; witnesses often interpret this decrease in brightness as recession into the distance. -the second object left the witness’s field of view at very high speed toward Bailleval (i.e. towards the north, thus against the wind): this point is absolutely contradictory with an object carried by the wind, unless it too is considered a perceptual illusion when the lantern is extinguished. -The return of the second object would then be a third lantern launched from the same place, toward Bailleval, a little after the first two. In conclusion, after taking into account the possibility of illusions of perception when the lights are extinguished, the GEIPAN classifies this case "B": probable observation of sky lanterns.