Martin Brenner's, Pilot Balloon Resources
AШT (ASHT) Aeorological Theodolite (pibal theodolite)
This theodolite produced in the Soviet Union (Moscow, Russia) in 1971. The model was in production through at least 1977.
This theodolite is the best ergonomic design (for a non digital) theodolite that I have seen. With the exception of the ability for a second observer to read the scales (the Met Office Pattern Theodolites allow this), it has a superior implementation of every desirable pilot balloon theodolite feature. The AWT uses friction driven circles which are read through the eyepiece. Unlike the Soviet ATK-2 which uses glass circles, this theodolite use metal circles and has a simplified optical path. The circles read directly to the tenth of a degree.
They are illuminated for low light viewing. The tripod mount is the modern tribrach type. The theodolite has a built in compass, and internal switchable filters. This theodolite is very compact and light yet features a large 40mm main objective (20 power), 10mm finder scope (4 power) and gun site. It included a manual and tools and a compact bullet case.
A unique aspect of this theodolite is that the reticule assembly is mechanically connected to the body of the theodolite not to the eyepiece tube. This allows the cross to maintain its vertical orientation regardless of the elevation of the telescope. A successor model produced in 1984 is described here.
The theodolite in case weighs only 6 pounds, and 12 in its case as compared to the Warren-knight 20-8403 which is on the order of 40 pounds in its case.
In the top photo above you can see two switches. One switches is for the finder scope/main objective change over, the second is to engage the available filters. The filter arrangement allows the insertion and removal of filters during an ascent. Very useful if the balloon crosses near the sun, or past a cloud.