MGS MAG magnetic field
MGS magnetic field is available in two coordinate systems:
- MSO (sun-state, ss)
The ss coordinate system is defined using the instantaneous
Mars-Sun vector as the primary reference vector (x direction).
The X-axis lies along this vector and is taken to be positive
toward the Sun. The Mars velocity vector is the second vector
used to define the coordinate system. The negative of the velocity
vector is used as a secondary reference vector so that the
vector cross product of x and y yields a vector z parallel to
the northward (upward) normal of the orbit plane of Mars. This
system is sometimes called a Sun-State (SS) coordinate system
since its principal vectors are the Sun vector and the Mars
state vector.
- Areographic (planetocentric, pc)
The planetocentric coordinate system is body-fixed and rotates
with the body as it spins on its axis. The body rotation axis
is the primary vector used to define this coordinate system. Z
is taken to lie along the rotation axis and be positive in the
direction of angular momentum. The X-axis is defined to lie in
the equatorial plane of the body, perpendicular to Z, and in
the direction of the prime meridian as defined by the IAU. The
Y axis completes the right-handed set.