The Reverend Gill "event" 
Many ufologists have provided much information on the 1959 Reverend Gill UFO sighting; here's Richard Hall's take:
But few UFO writers have zeroed in on the psychological aspects of the sighting, preferring to cite Venus as a possible instigator, even though the planet was seen elsewhere in the sky Gill reported.
The sighting might be a case of induced hallucination or folie communiquee where a delusion is shared with or by others.
While that seems unlikely from accounts of the "event," the possibility is acute, considering Reverend Gill's position or status among the natives whom he served and with whom he saw the apparition.
I've posted, recently, other sightings that are similar to the Gill observation, and note, here, that there is, as far as I know, no recent sightings that emulate the Gill event. This, and a few others in the 1960s, seem to be unique, and intrigue.
The hallucinatory elements of the sighting stand out, certainly, but aren't all UFO sightings, especially those involving alleged creatures or beings, hallucinatory in nature?
This sighting, the Gill event, has not been fully testimated and remains, like Socorro , a fascinating observation that is not unlike many seen in earlier times as noted in the Vallee/Aubeck book, Wonders in the Sky and Richard Nolan's new book: UFOs for the 21st Century Mind: A Fresh Guide to an Ancient Mystery.