vertical circle telescope

A vertical circle telescope is a specialized astronomical instrument designed for precise measurements of celestial objects. It is a type of transit instrument, meaning its primary function is to observe celestial bodies as they cross the observer's meridian.12

These telescopes are typically refractors with apertures ranging from 6 to 8 inches. The key feature of a vertical circle telescope is that its optical axis is aligned with the north-south line, restricting its movement to the plane of the meridian. This design enhances stability.2

While transit instruments, in general, are used to determine celestial objects' right ascension and declination, a vertical circle telescope specifically measures only their declinations. The name "transit" comes from the observation of a celestial object "transiting" the meridian.2