Sighting in La Mure, November 21, 1978

A witness driving to work noticed a coloured luminous phenomenon about halfway up Mont Cimon. They watched it for roughly three minutes: it moved rapidly and changed course several times, then went around the mountain on the left and disappeared.

When giving a statement to the gendarmerie, the witness said that a neighbour had seen a similar phenomenon in the direction of the same mountain on 18 and 19 November 1978, at around 9:45 pm. The two witnesses were independent of each other, and their accounts matched closely.

The GEIPAN investigation retained a hypothesis consistent with all the descriptions: a P.L.O.T. (Transient Stormy Luminous Phenomenon, or Phénomène Lumineux Orageux Transitoire), a rare phenomenon whose study has developed in recent years. An expert from the Lightning Research Laboratory, a GEIPAN partner, was consulted. Such a phenomenon appears in anticyclonic weather and near electrical installations, two conditions that fit the site. Its appearance, a sphere surrounded by a halo, matches many P.L.O.T. observations; it can last several minutes, stay still and recur over several days. The forest on the hillside, with electrical flows above the trees, favours its rapid movements. Local weather conditions could not be checked, but this does not invalidate the hypothesis. The case was classified B: probable observation of a P.L.O.T. It had originally been classified D, before being re-examined.