ARGENTEUIL (95) 13.07.1979

GEIPAN continues to publish its entire archive on www.geipan.fr. Older cases originally classified A, B, C or D are now being reassessed solely to improve their conclusions. New technical tools (software) and accumulated investigative experience sometimes lead to new observations or even a change in classification. This case, previously classified D and named ARGENTEUIL (95) 13.07.1979, is among those recently reassessed. On 13 July 1979 around 23:30, 2 witnesses on a 7th-floor balcony saw a red-orange ball coming from the north-west towards central Paris. The UAP seemed to stop above La Défense–Nanterre and abruptly went out. The sighting lasted about 30 seconds. Three minutes later, where the first UAP had disappeared, they saw a flat, bright white form move through the sky and disappear very rapidly along an ascending path. The source summary additionally describes a trail of incandescent light with the white UAP and calls the first UAP bright red, while the narrative describes it as red-orange. They were astonished. No other accounts were collected. Some features initially suggest 2 misidentifications, first an aircraft and then a fireball (see the investigation report). The aircraft hypothesis fits the red colour, since aircraft headlights can appear red in certain configurations, and an initial speed the witness judged similar to an aeroplane’s. The fireball hypothesis fits the white colour, high brightness, “ascent into space” compatible with a path towards the zenith, and a “flat” shape surrounded by a “round” one. However, GEIPAN identifies uncertainties and unusual features under this double explanation. The first phase ended with a stop and then extinction. The aircraft would therefore have to be a helicopter, with a cloud causing the light to disappear. The second phase began in the same place, requiring a chance coincidence if it were a fireball. The account seems to describe it as a resumption of the first phase, whereas a fireball’s apparent speed is quite unlike an aircraft’s. A right-angle turn is also reported after the resumption: “The craft then traced a right angle in a fraction of a second, before rising into space at a speed defying all the known laws of modern technology.” The description is ambiguous. “Rising into space” can describe the familiar impression produced by a light fading and disappearing. A witness may interpret a gradual disappearance as a UAP rapidly receding, without necessarily perceiving angular movement. The reported turn might then result from connecting this apparent departure into space with the first phase’s horizontal movement. That interpretation would no longer fit a fireball, but could fit aircraft headlights switching off or a star being obscured by a cloud. No bright star lay towards Nanterre, however. If it was the first phase’s aircraft, its changed appearance and colour would need explaining. GEIPAN regards this as possible in a scenario already involving clouds altering light intensity and consequently the colours of the lights. The observation has weak evidential strength. Essential information is missing: - A verified duration for the second UAP. - The UAPs’ elevations above the horizon. - Precise appearance azimuth for the second UAP and disappearance azimuths for both; the witnesses did supply the first UAP’s appearance azimuth. - Both UAPs’ angular length and width. - A separate account from the second witness. The witnesses were probably interviewed together and their accounts combined into 1 statement. - The gendarmes conducted no investigation. Hypotheses could explain the observation, but their uncertainty is too great given the limited amount and reliability of the evidence. The case is classified C: it cannot be meaningfully analysed for lack of reliable information.