VILLEJUST (91) 29.08.2017

On the evening of 29 August 2017, several people in Villejust (91) saw a section of green light beam in a cloudy night sky, disappearing and reappearing a few moments later in the same place. The reporting witness took photographs. They watched for about 1 hour before going to bed. Afterwards he noticed white or blue balls of light in the photographs. Only 1 account was collected. GEIPAN assessed the case as low in strangeness and well supported by 3 witnesses, 1 account and photographs. It identified the IPRAL laser at École Polytechnique's SIRTA observatory, together with stars; see the investigation report. The source also misspells the observatory as SITRA in its explanatory paragraphs. The main UAP's green colour and vertical orientation strongly suggested the observatory's laser, and its direction matched the observatory. Contacted during the investigation, the observatory confirmed that IPRAL was operating at the time. The points discovered afterwards in the photographs were very probably stars: their relative positions remained unchanged in images taken several minutes apart. Double points could have resulted from camera movement during exposure. GEIPAN classified the case A: observation of the IPRAL laser at SIRTA, École Polytechnique, and stars.