meridian circle

noun, Astronomy
1.
a transit instrument provided with a graduated vertical scale, used to measure the declinations of heavenly bodies and to determine the time of meridian transits.
Also called circle, transit circle, transit instrument.
Origin
1540-50
British Dictionary definitions for meridian circle

meridian circle

noun
1.
an instrument used in astronomy for determining the declination and right ascension of stars. It consists of a telescope attached to a graduated circle