There are several geocentric coordinate systems in use, the most obvious and best known being the geographic system. Some of them are listed below with some heliocentric systems:
Geocentric coordinate systems | ||
---|---|---|
Geocentric equatorial inertial | GEI | X=First point of Aries Z=Geographic North Pole |
Geographic | GEO | X=Intersection of Greenwich meridian and geographic equator Z=Geographic North Pole |
Geocentric solar ecliptic | GSE | X=Earth-Sun line Z=Ecliptic North Pole |
Geocentric solar magnetospheric | GSM | X=Earth-Sun line Z=Projection of dipole axis on GSE YZ plane |
Solar magnetic | SM | Y=Perpendicular to plane containing Earth-Sun line and dipole axis. Positive sense is opposite to Earth's orbital motion Z=Dipole axis |
Geomagnetic | MAG | Y=Intersection between geographic equator and the geographic meridian 90 degrees east of the meridian containing the dipole axis Z=Dipole axis |
Heliocentric systems | ||
Heliocentric Aries ecliptic | HAE | X=First point of Aries Z=Ecliptic North Pole |
Heliocentric Earth ecliptic | HEE | X=Sun-Earth line Z=Ecliptic North Pole |
Heliocentric Earth equatorial | HEEQ | X=Intersection between solar equator and solar central meridian as seen from Earth Z=North Pole of solar rotation axis |
Also a system called Corrected GeoMagnetic (CGM) coordinates exists (see here for more details and online calculation service!). For L-values see, e.g., IGRF page of NSSDC (see also our magnetic field models page). There exist also an Altitude Adjusted Corrected Geomagnetic coordinates (AACGGM) system and an Apex magnetic coordinate system (Richmond, 1995).
Boundary normal coordinates are defined relative to some natural boundary such as the magnetopause or the bow shock. They allow the data to be ordered in a way which is related to that boundary. Two of the axes lie in a plane tangential to the boundary, and one axis is normal to this boundary. For more information see, e.g., Kawano and Higuchi (1996).
A good description how to make transformations between the different coordinate systems can be found in a paper by Hapgood (1992). Similar routines are also included in the famous Tsyganenko magnetic field models.