Meridian circle
ASTRONOMICAL INSTRUMENT FOR TIMING OF THE PASSAGE OF STARS
Transit circle; Meridian Circle; Mural circle; Meridian telescope; Transit Circlet; Transit Circle; Declination circle; Meridian-circle; Rota meridiana; Meridian circles
The meridian circle is an instrument for timing of the passage of stars across the local meridian, an event known as a culmination, while at the same time measuring their angular distance from the nadir. These are special purpose telescopes mounted so as to allow pointing only in the meridian, the great circle through the north point of the horizon, the north celestial pole, the zenith, the south point of the horizon, the south celestial pole, and the nadir.