Page 3 - Three New Tables for an Astrology of Three Dimensions

A location in the axial system of spherical coordinates is fixed on
the surface of the earth; it does not change with diurnal rotation. It
should also be recognized that these coordinates are not dependent on
the radius of the earth: they can be extended out into space indefinitely
and related to planetary positions (declination is based on an infinitely
extended plane of the equator).
Nevertheless, the axial system of coordinates is not used in
ephemerides to locate the positions of the planets; another system, the
“ecliptic,” is used. The poles of this system also pass through the
center of the earth, but are perpendicular to the plane of the earth’s
orbit (the ecliptic). Measurements are made from the point where a
particular line of ecliptic longitude (0º Aries) intersects the great circle
perpendicular to it (the ecliptic).

Unlike the axial system, the ecliptic system is not fixed to the
rotating surface of the earth. However, since the poles of the ecliptic
system rotate annually around the sun, any position in ecliptic
coordinates must take into account the increment of Sidereal Time
(S.T., provided in ephemerides).
The third system of spherical coordinates to be considered is the
“local.” It involves a slight distortion, traditionally ignored because in
most cases it alters planetary positions by less than one minute of arc.
Every position on the surface of the earth has a unique zenith and
horizon. By lowering the intersection of that line with that plane to the
center of the earth, the basis is created for a system of coordinates
whose northern or upper pole is the zenith.