|
Information
about STEREO-A close approach to Earth, August 2023
Explanation of Coordinate Systems
The coordinate systems used on the
"Where is STEREO?"
page follow the definitions given in the following references
- Fränz, M. and Harper, D. (2002). Heliospheric coordinate
systems. Planetary and Space Science, 50, 217-239.
- Hapgood, M. A. (1992). Space physics coordinate transformation: A user
guide. Planetary and Space Science, 40, 711-717.
- Russell, C. T. (1971). Geophysical coordinate transformations. Cosmic
Electrodynamics, 2, 184-196.
Below, each coordinate system is summarized.
Note that the various ecliptic coordinate systems can differ in how precession
is handled. Ecliptic coordinates can either be referenced to the J2000 epoch,
or precessed to the epoch of date. We follow the conventions of Fränz and
Harper (2002) in deciding which to apply for each coordinate system.
In the table below, the notation "J2000" means that the coordinates are
referenced to the J2000 epoch, while "D" means that the coordinates were
precessed to the mean ecliptic of date.
For each coordinate system, two axes are given. The third axis in each case
completes the right-handed system.
| Geocentric coordinate systems |
|---|
| GEI | Geocentric Equatorial Inertial |
X=First point of Aries
Z=Geographic north pole |
J2000 |
| GEO | Geographic |
X=Intersection of Greenwich meridian and geographic equator
Z=Geographic north pole |
|
| GSE | Geocentric Solar Ecliptic |
X=Earth-Sun line
Z=Ecliptic north pole |
D |
| Heliocentric coordinate systems |
|---|
| HCI | Heliocentric Inertial |
Z=Solar rotational axis
X=Solar ascending node on ecliptic |
J2000 |
| HAE | Heliocentric Aries Ecliptic |
X=First point of Aries
Z=Ecliptic north pole |
J2000 |
| HEE | Heliocentric Earth Ecliptic |
X=Sun-Earth line
Z=Ecliptic north pole |
D |
| HEEQ | Heliocentric Earth Equatorial |
Z=Solar rotation axis
X=intersection of solar equator and solar central meridian as seen
from Earth |
|
The calculations are based on the JPL/NAIF
SPICE
package, using IDL
software which is available as part of the
Solar Software Library.
A user's guide is available in both
PDF and
Postscript formats.
Roll angles for the two spacecraft are defined such that the nominal
orientation of each spacecraft is close to zero degrees. This is done by
subtracting 180 degrees from the Behind values reported by the spacecraft.
After the two spacecraft pass behind the Sun in 2015, the definition of
"nominal" orientation will need to be changed--this is not currently handled
by the software.
Last Revised: Thursday, 22-Apr-2010 21:10:37 UTC
Responsible NASA Official: ![[email address: Therese.A.Kucera<at>nasa<dot>gov]](/img/kucera_email1.jpg)
Accessibility
Privacy Policy and Important Notices
Feedback and comments: webmaster
| 
