One saucer was observed by two independent witnesses near a nuclear test site for ten minutes.

Hynek quotes the witness:

Very briefly, what I saw was a small silvery white disc of unknown diameter, unknown altitude, but definite physical existence; it first appeared stationary, under visual observation, for about ten minutes. Then it moved across the sky, visually passing under the clouds and finally disappearing into the white clouds. No sound could be detected. The white dot stood still too long and moved too silently to have been an aircraft; it appeared to travel in a direction distinctly inconsistent with the direction of the clouds so as to preclude . .. that it was a balloon

Google map of this location.