GEIPAN Case 2012-07-08299 — MONTCHABOUD (38) 26.07.2012

Brief

On July 26, 2012 at 22:20, a retired amateur astronomer in Montchaboud (Isère, France) observed a silent, vaporous, dimly luminous sphere — slightly larger than the Moon — traverse the sky from south-southeast to zenith in 3 to 6 seconds. GEIPAN investigators, including the unit chief, personally interviewed the witness in October 2012 and systematically ruled out wind-borne objects, spacecraft degassing, cometary phenomena, atmospheric reentry, meteorological plasma, insect swarms, and ocular phosphenes. Satellite-pass data from Calsky.com confirmed no known object was on the observed track at the stated time. The case was formally closed as D1 (unexplained) with a consistency score of 0.75 and strangeness of 0.6 out of 1.0; the sole limiting factor was the absence of photographic or video corroboration.

Metadata

Agency

GEIPAN / CNES

Release

2007-03-22

Type

PDF • .pdf

Length

10 pages

Classification

UNCLASSIFIED

Programs

GEIPAN

Tags

vaporous sphere, silent, straight-line trajectory, visual only, Montchaboud France, 2012, GEIPAN D1, sub-object luminous points

Key points

• Single civilian witness — a retired amateur astronomer with no prior interest in UAP — observed a vaporous, silent sphere slightly larger than the Moon moving in a straight S-N line from horizon to zenith in 3 to 6 seconds at 22:20 on July 26, 2012.p.1
• The object was described as gray-silver, dimly luminous (less than the Moon but more than the Andromeda nebula), disc-shaped with a faint trail, and displaying luminous points beneath it when near zenith.p.2
• The witness waited two hours after the observation hoping the phenomenon would return, then took written notes before filing a gendarmerie report on August 2, 2012.p.2
• Calsky.com satellite-pass data showed no known object on the described trajectory at the stated time.p.6
• Weather records showed light, unstable winds with the nearest station (Versoud) recording a northward wind — directly opposing the observed south-to-north trajectory, undermining the wind-borne object hypothesis.p.5
• GEIPAN assigned the unit chief and a second investigator to conduct a personal field interview at the witness's home on October 2, 2012.p.1
• Seven hypotheses were evaluated — wind-borne object, spacecraft degassing, cometary/astronomical phenomenon, atmospheric reentry, meteorological plasma, mosquito swarm, and ocular phosphene — and none adequately matched all observed parameters.p.9
• The case was classified D1 (unexplained) with a consistency score of 0.75 and a strangeness score of 0.6 out of 1.0.p.10

Verbatim

• une masse, semblant tourbillonner, au contour diffus, à peu près sphérique, qui avançait en ligne droite depuis le Sud-Sud Est puis a mis 3 à 6 secondes pour arriver au zénith, point à partir duquel la maison masque le ciel vers le nord.

  p.1

• Sa luminosité était relativement faible : bien moins lumineux que la Lune, mais bien plus que la nébuleuse d'Andromède : la luminosité a semblé un peu plus importante lorsque l'objet était au zénith.

  p.2

• Le témoin a déjà pu observer de la foudre en boule : ce n'était pas du tout ça, c'était bien moins lumineux.

  p.2

• Le relevé des passages de satellites établi par Calsky.com (voir en annexe) ne montre aucun objet sur la trajectoire décrite par le témoin à l'heure dite.

  p.6

• Etant donné que le vent était très faible, l'objet aurait dû être très bas pour qu'il traverse le ciel en quelques secondes : le témoin l'aurait probablement identifié.

  p.7

• La consistance du cas est bonne, avec un témoignage de grande qualité, très précis, bien documenté, rédigé par le témoin aussitôt la fin de l'observation. Mais ceci reste un témoignage unique, sans photo ni vidéo.

  p.10

• Le GEIPAN, n'ayant pu confirmer aucune des hypothèses envisagées, classe ce cas « D1 » comme inexpliqué.

  p.10

Most interesting

• The GEIPAN unit chief personally traveled to the witness's home for the field interview — an indication of the case's perceived significance despite having only one witness.
• The witness, who had been observing the night sky from the same south-facing balcony since 1980, explicitly ruled out ball lightning from personal prior experience.
• The phosphene hypothesis — that the witness experienced a vision artifact from a cardiovascular episode — was noted as plausible given his medical history but could not be formally evaluated because GEIPAN was unable to consult his treating physician.
• The formal investigation report was issued February 3, 2014, nearly 18 months after the July 2012 observation, suggesting an unusually extended review process for a single-witness case.
• The object covered approximately 90 degrees of sky arc (horizon to zenith) in 3 to 6 seconds, a geometric constraint the investigation could not resolve into either a slow low-altitude object or a fast high-altitude one.
• GEIPAN rated both consistency and strangeness above the midpoint (0.75 and 0.6 respectively), placing this case in the upper tier of its D1 (unexplained) classification band.