Coordinate Systems for ACE
A good description of how to make transformations between the different
coordinate systems can be found in a paper by M. A. Hapgood, "Space physics
coordinate transformations: A user guide", in Planetary and Space Science, Vol.
40, No. 5, pp. 711717, 1992.

J2000 GCI
 Geocentric inertial reference frame using the Julian Epoch of Jan. 1,
2000.
 At the Julian Epoch,
 X = First point of Aries (Vernal Equinox, i.e. from Earth to the Sun in
the first day of Spring)
 Z = Earth's mean spin axis

RTN  Radial Tangential Normal
 Spacecraft centered coordinate system.
 R = Sun to Spacecraft unit vector
 T = (Omega x R) /  (Omega x R) 
 where Omega is Sun's spin axis (in J2000 GCI)
 N completes the righthanded triad

 X = EarthSun Line
 Z = Ecliptic North Pole

 X = EarthSun Line
 Z = Projection of dipole axis on GSE YZ plane

HSEa  Heliocentric Solar Ecliptic (Inertial)
 X = First poin tof Aries (Vernal Equinox, i.e. to the Sun from Earth in
the first day of Spring)
 Z = Ecliptic North Pole

HSEb  Heliocentric Solar Ecliptic (Earth Oriented)
 X = SunEarth Line
 Z = Ecliptic North Pole

HS  Heliocentric Solar
 X = Intersection between solar equator and solar central meridian as seen
from Earth
 Z = North Pole of solar rotation axis
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системы координат, преобразования
Last Updated: Sep 15, 1998, 30.08.15