A vertical circle is any great circle that passes through the zenith.
Reflection from an excess of horizontal prisms gives rise to a vertical circle passing through the sun.
The altitude of a celestial object is its distance above the horizon measured on the arc of a vertical circle.
The Azimuth of a star is the angle between the meridian and the vertical circle passing through the star.
The meridian is that vertical circle which passes through the north and south points.
The prime vertical is that vertical circle which passes through the east and west points.
The altitude of a body is its elevation above the horizon, measured on a vertical circle.
The azimuth of a body is its distance, measured on the horizon, from the meridian to a vertical circle passing through that body.
The amplitude of a body is its distance, on the horizon, from the prime vertical to a vertical circle passing through the body.
The zenith distance of a body is measured on a vertical circle passing through that body.
vertical circle A great circle on the celestial sphere that passes through the zenith and the nadir and thus is perpendicular to the horizon. |