enumeration 
CGM 
Corrected Geomagnetic  A coordinate system
from a spatial point with GEO radial distance
and geomagnetic latitude and longitude, follow
the epochappropriate IGRF/DGRF model field
vector through to the point where the field
line crosses the geomagnetic dipole equatorial
plane. Then trace the dipole magnetic field
vector Earthward from that point on the equatorial
plane, in the same hemisphere as the original
point, until the initial radial distance is
reached. Designate the dipole latitude and
longitude at that point as the CGM latitude
and longitude of the original point. See <http://nssdc.gsfc.nasa.gov/space/cgm/cgmm_des.html> 

enumeration 
CSO 
Corrected Solar Orbital  A coordinate system
related to Earth where X is antisunward,
Y along the orbital velocity direction. 

enumeration 
Carrington 
A coordinate system which is centered at the
Sun and is "fixed" with respect to the synodic
rotation rate; the mean synodic value is about
27.2753 days. The Astronomical Almanac gives
a value for Carrington longitude of 349.03
degrees at 0000 UT on 1 January 1995. 

enumeration 
DM 
Dipole Meridian  A coordinate system centered
at the observation point. Z axis is parallel
to the Earth's dipole axis, positive northward.
X is in the plane defined by Z and the line
linking the observation point with the Earth's
center. Y is positive eastward. See <http://cdpp.cnes.fr/00428.pdf> 

enumeration 
ECEF 
The EarthCentered, EarthFixed (ECEF) coordinate
system has point (0,0,0) defined as the center
of mass of the Earth. Its axes are aligned
with the International Reference Pole (IRP)
and International Reference Meridian (IRM).
The xaxis intersects the sphere of the Earth
at 0 degree latitude (Equator) and 0 degree
longitude (Greenwich). The zaxis points north.
The yaxis completes the right handed coordinate
system. 

enumeration 
ENP 
ENP (also called PEN)  The P vector component
points northward, perpendicular to orbit plane
which for a zero degree inclination orbit
is parallel to Earth's spin axis. The E vector
component is perpendicular to P and N and
points earthward. The N component is perpendicular
to P and E and is positive eastward. 

enumeration 
GEI 
GEI Geocentric Equatorial Inertial  A coordinate
system where the Z axis is along Earth's spin
vector, positive northward. X axis points
towards the first point of Aries (from the
Earth towards the Sun at the vernal equinox).
See Russell, 1971. When the X axis is the
direction of the mean vernal equinox of J2000,
the coordinate system is also called GCI.
Then the Z axis is also defined as being normal
to the mean Earth equator of J2000. 

enumeration 
GEO 
Geographic  geocentric corotating  A coordinate
system where the Z axis is along Earth's spin
vector, positive northward. X axis lies in
Greenwich meridian, positive towards Greenwich.
See Russell, 1971. 

enumeration 
GPHIO 
Kronian Solar Orbital  A coordinate system
related to Saturn where X is antisunward,
Y along the orbital velocity direction. 

enumeration 
GSE 
Geocentric Solar Ecliptic  A coordinate system
where the X axis is from Earth to Sun. Z axis
is normal to the ecliptic, positive northward.
See Russell, 1971. 

enumeration 
GSEQ 
Geocentric Solar Equatorial  A coordinate
system where the X axis is from Earth to Sun.
Y axis is parallel to solar equatorial plane.
Z axis is positive northward. See Russell,
1971 

enumeration 
GSM 
Geocentric Solar Magnetospheric  A coordinate
system where the X axis is from Earth to Sun,
Z axis is northward in a plane containing
the X axis and the geomagnetic dipole axis.
See Russell, 1971 

enumeration 
HAE 
Heliocentric Aries Ecliptic  A coordinate
system where the Z axis is normal to the ecliptic
plane, positive northward. X axis is positive
towards the first point of Aries (from Earth
to Sun at vernal equinox). Same as SE below.
See Hapgood, 1992. 

enumeration 
HCC 
Heliocentric Cartesian  A 3D orthonormal
coordinate system that is primarily intended
to specify with two dimensions a point on
the solar disk. The Z axis points toward the
observer. The Y axis lies in the plane defined
by the solar spin vector and the Z axis, positive
northward. The X axis is perpendicular to
the Y and Z axes, positive toward solar west.
Standard representation for this system is
via the point's x and y values, expressed
either as physical distances or as fractions
of the solar disk radius. 

enumeration 
HCI 
Heliographic Carrington Inertial. 

enumeration 
HCR 
Heliocentric Radial  A 3D orthonormal coordinate
system that is primarily intended to specify
with two dimensions a point on the solar disk.
The Z axis points toward the observer. The
Y axis lies in the plane defined by the solar
spin vector and the Z axis, positive northward.
The X axis is perpendicular to the Y and Z
axes, positive toward solar west. Standard
representation for this system is via the
point's distance rho from the Z axis [Rho
= SQRT(x**2 + y**2)] and its phase angle psi
measured counterclockwise from the +Y axis
[psi = arctan (y/x)] 

enumeration 
HEE 
Heliocentric Earth Ecliptic  A coordinate
system where the Z axis is normal to the ecliptic
plane, positive northward. X axis points from
Sun to Earth. See Hapgood, 1992 

enumeration 
HEEQ 
Heliocentric Earth Equatorial  A coordinate
system where the Z axis is normal to the solar
equatorial plane, positive northward. X axis
is generally Earthward in the plane defined
by the Z axis and the SunEarth direction.
See Hapgood, 1992. 

enumeration 
HG 
Heliographic  A heliocentric rotating coordinate
system where the Z axis is normal to the solar
equatorial plane, positive northward. X, Y
axes rotate with a 25.38 day period. The zero
longitude (X axis) is defined as the longitude
that passed through the ascending node of
the solar equator on the ecliptic plane on
1 January, 1854 at 12 UT. See <http://nssdc.gsfc.nasa.gov/space/helios/coor_des.html> 

enumeration 
HGI 
Heliographic Inertial  A heliocentric coordinate
system where the Z axis is normal to the solar
equatorial plane, positive northward. X axis
is along the intersection line between solar
equatorial and ecliptic planes. The X axis
was positive at SE longitude of 74.367 deg
on Jan 1, 1900. (See SE below.) See <http://nssdc.gsfc.nasa.gov/space/helios/coor_des.html> 

enumeration 
HPC 
Helioprojective Cartesian = A 3D orthonormal
(lefthanded) coordinate system that is primarily
intended to specify with two dimensions a
point on the solar disk. The Z axis points
from the observer to the center of the solar
disk. The Y axis lies in the plane defined
by the solar spin vector and the Z axis, positive
northward. The X axis is perpendicular to
the Y and Z axes, positive toward solar west.
Given as the distance between the observer
and the center of the solar disk, the standard
representation of an (x,y) point on the solar
disk is via the point's longitude angle [arctan
(x/d)] and latitude angle [arctan y/d]. 

enumeration 
HPR 
Helioprojective Radial  A 3D orthonormal
(lefthanded) coordinate system that is primarily
intended to specify with two dimensions a
point on the solar disk. The Z axis points
from the observer to the center of the solar
disk. The Y axis lies in the plane defined
by the solar spin vector and the Z axis, positive
northward. The X axis is perpendicular to
the Y and Z axes, positive toward solar west.
Given as the distance between the observer
and the center of the solar disk, the standard
representation for this system of an (x,y)
point on the solar disk is via the point's
latitude angle theta {= arctan [SQRT(x**2
+ y**2)]/d]} or equivalent declination parameter
delta (= theta  90 deg), and its phase angle
psi as measured counter clockwise from the
+Y axis [psi = arctan (y/x)]. 

enumeration 
HSM 
Heliospheric Solar Magnetospheric  A coordinate
system where the X axis is from Earth to Sun,
Z axis is northward in a plane containing
the X axis and the geomagnetic dipole axis. 

enumeration 
J2000 
An astronomical coordinate system which uses
the mean equator and equinox of Julian date
2451545.0 TT (Terrestrial Time), or January
1, 2000, noon TT. (aka J2000) to define a
celestial reference frame. 

enumeration 
JSM 
Jovian Solar Magnetospheric  A coordinate
system related to Jupiter where the X axis
is from Jupiter to Sun, Z axis is northward
in a plane containing the X axis and the Jovian
dipole axis. 

enumeration 
JSO 
Jovian Solar Orbital  A coordinate system
related to Jupiter where X antisunward, Y
along the orbital velocity direction. 

enumeration 
KSM 
Kronian Solar Magnetospheric  A coordinate
system related to Saturn where the X axis
is antisunward, Z axis is northward in a
plane containing the X axis and the Kronian
dipole axis. 

enumeration 
KSO 
Kronian Solar Orbital  A coordinate system
related to Saturn where X is antisunward,
Y along the orbital velocity direction. 

enumeration 
LGM 
Local Geomagnetic  A coordinate system used
mainly for Earth surface or near Earth surface
magnetic field data. X axis northward from
observation point in a geographic meridian.
Z axis downward towards Earth's center. In
this system, H (total horizontal component)
= SQRT (Bx^2 + By^2) and D (declination angle)
= arctan (By/Bx) 

enumeration 
MAG 
Geomagnetic  geocentric. Z axis is parallel
to the geomagnetic dipole axis, positive north.
X is in the plane defined by the Z axis and
the Earth's rotation axis. If N is a unit
vector from the Earth's center to the north
geographic pole, the signs of the X and Y
axes are given by Y = N x Z, X = Y x Z.. See
Russell, 1971, and <http://cdpp.cnes.fr/00428.pdf> 

enumeration 
MFA 
Magnetic Field Aligned  A coordinate system
spacecraftcentered system with Z in the direction
of the ambient magnetic field vector. X is
in the plane defined by Z and the spacecraftSun
line, positive sunward. See <http://cdpp.cnes.fr/00428.pdf> 

enumeration 
MSO 
Mars/Mercury Solar Orbital A coordinate system
related to Mars or Mercury. A coordinate system
where, depending on the body (Mars or Mercury),
X is antisunward, Y along the orbital velocity
direction. 

enumeration 
RTN 
Radial Tangential Normal. Typically centered
at a spacecraft. Used for IMF and plasma V
vectors. R (radial) axis is radially away
from the Sun, T (tangential) axis is normal
to the plane formed by R and the Sun's spin
vector, positive in the direction of planetary
motion. N (normal) is R x T. 

enumeration 
SC 
Spacecraft  A coordinate system defined by
the spacecraft geometry and/or spin. Often
has Z axis parallel to spacecraft spin vector.
X and Y axes may or may not corotate with
the spacecraft. See SR and SR2 below. 

enumeration 
SE 
Solar Ecliptic  A heliocentric coordinate
system where the Z axis is normal to the ecliptic
plane, positive northward. X axis is positive
towards the first point of Aries (from Earth
to Sun at vernal equinox). Same as HAE above.
See <http://nssdc.gsfc.nasa.gov/space/helios/coor_des.html> 

enumeration 
SM 
Solar Magnetic  A geocentric coordinate system
where the Z axis is northward along Earth's
dipole axis, X axis is in plane of z axis
and EarthSun line, positive sunward. See
Russell, 1971. 

enumeration 
SR 
Spin Reference  A special case of a Spacecraft
(SC) coordinate system for a spinning spacecraft.
Z is parallel to the spacecraft spin vector.
X and Y rotate with the spacecraft. See <http://cdpp.cnes.fr/00428.pdf> 

enumeration 
SR2 
Spin Reference 2  A special case of a Spacecraft
(SC) coordinate system for a spinning spacecraft.
Z is parallel to the spacecraft spin vector.
X is in the plane defined by Z and the spacecraftSun
line, positive sunward. See <http://cdpp.cnes.fr/00428.pdf> 

enumeration 
SSE 
Spacecraft Solar Ecliptic  A coordinate system
used for deep space spacecraft, for example
Helios.  X axis from spacecraft to Sun. Z
axis normal to ecliptic plane, positive northward.
Note: Angle between normals to ecliptic and
to Helios orbit plane ~ 0.25 deg. 

enumeration 
SSE_L 
Selenocentric Solar Ecliptic. The X axis
points from the center of the Earth's moon
to the sun, the Z axis is normal to the ecliptic
plane, positive northward. And the Y axis
completes the righthanded set of axes. 

enumeration 
SpacecraftOrbitPlane 
A coordinate system where X lies in the plane
normal to and in the direction of motion of
the spacecraft, Z is normal to this plane
and Y completes the triad in a righthanded
coordinate system. 

enumeration 
TIIS 
Kronian Solar Orbital  A coordinate system
related to Saturn where X is antisunward,
Y along the orbital velocity direction. 

enumeration 
VSO 
Venus Solar Orbital  A coordinate system
related to Venus where X is antisunward,
Y along the orbital velocity direction. 

enumeration 
WGS84 
The World Geodetic System (WGS) defines a
reference frame for the earth, for use in
geodesy and navigation. The WGS84 uses the
zero meridian as defined by the Bureau International
de l'Heure. 
