The Astrology of Space - Matrix Software

The Astrology of Space
Horizon Coordinate System
In this system a plane through the observing point
parallel to the horizon is the plane of reference. The
poles are the Zenith (point overhead) and the Nadir
(point underfoot). The vertical circle through a
celestial object (such as a star) and the zenith is the
Object Circle. The coordinates are given (for the
object) by Azimuth (horizontal angle measured from
an arbitrary reference direction – East in our case –
counterclockwise to the object circle) and the Altitude
(elevation angle measured upward from the horizon to
the object). The great circle through the north and
south points and the zenith is the Meridian, and the
great circle through the east and west points and the
zenith is the Prime Vertical. Circles of parallel altitude
to the horizon that are not great circles are called
Almucantars.
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