Sighting in Poissy, September 7, 2013

On a Saturday, between 1:10 and 1:40 pm, a motorist driving north-east saw a long white cylinder about 15° above the horizon. The object moved away in a straight line and then disappeared in the direction of Poissy. No other witness account was collected.

Weather records showed a south-westerly wind at Toussus-le-Noble and a westerly wind at Pontoise, so the wind at the location was estimated to be from the south-west to west. The sighting is consistent with a cylindrical balloon carried by the wind. The shape suggests a hot-air balloon, or solar balloon, which could have been released at Orgeval or Feucherolles, or even from much farther away, since such balloons can stay airborne for hours. A associations forum was being held in both of those towns that day. These balloons are often dark grey or transparent, so the white colour may have come from sunlight, with the sun almost at its zenith, reflecting off the object.

GEIPAN classified the case as B: a case of low strangeness, probably a balloon. Because of this, no field investigation was justified, as it would have been too uncertain in an urban area for this kind of phenomenon.