Define (Planet)
Define the basic properties of a planet
Syntax
Define <PlanetObjectPath> {Method} <Parameters>
Description
The Define command enables you to define a planet and its ephemerides by indicating the {Method} by which the planet will be defined and supplying the <Parameters> necessary to do so. Valid {Methods} and their associated <Parameters> are outlined below.
| {Method} | <Parameters> |
|---|---|
| CentralBody | {CBName} [{EphemerisSource}] [Rename] |
| File | "<FilePath.pe>"
Specify a planet ephemeris file, with a .pe extension. "<FilePath>" is the path to a file on your local drive. |
{CBName} can be the name of any registered central body. Valid values for the optional {EphemerisSource} parameter are outlined in the following Table:
| {EphemerisSource} | Description |
|---|---|
| Default | Use STK's internal definition of the celestial body to generate ephemeris. By default, STK's internal definition uses the DE file if available. |
| JPL | DE430 database: This provides ephemerides for each planet in the solar system plus Pluto, the Sun, and Earth's Moon. Ephemerides, supplied by JPL, cover a time span from 1960 to 2060. |
| SPICE | Use the SPICE ephemeris file (*.bsp) that has been loaded for this planet. All SPICE ephemeris files in the <STK install folder>\STKData\Spice and the <STK user area>\Config\Spice directories are loaded automatically when STK starts. |
| Analytic | Use an analytic propagator. This is available when orbital elements are known for the celestial body about its parent. |
Use the optional Rename parameter if you want the Planet's name to be the same as that of the body it represents (e.g., you want to call Mars "Mars").
The JPL option provides the location of the barycenter of a planetary system, whereas the SPICE toolkit option provides the location of the planet's center.
Examples
Return message
Group membership
This command belongs to the following group(s):
Version
12.10