< arrey intro
The UFO Sighting at Arrey
Charles B Moore and his crew launched a "pibal" - a neoprene rubber "pilot balloon" - which would be observed through a 25-power David White ML-47 theodolite. Pibals were typically launched before large balloon flights to help predict the path the bigger balloon would follow.
See: Pilot Balloons: A 1944 US Navy manual on the process of launching and tracking weather balloons
Pibals being launched by Skyhook crew (USAF)
Below, diagrams show details of typical theodolite of the period: