External Propagator

The StkExternal propagator enables you to import the ephemeris for a vehicle directly from a file. This is useful when the ephemeris has been obtained from a source other than STK, but the user wants to do further analysis within STK. The file contains ephemeris information such as position and velocity in a variety of formats and coordinate types. For more details of the exact format, see the help on the ephemeris files (*.e) format. External ephemeris files may also be created within STK using the Create Data File tool.

To use an external ephemeris file to propagate a vehicle:

1. Select the StkExternal Propagator.
   
   
2. Type the file path and name of the external ephemeris file in the text box, or use the button to browse for a file.

   NOTE: Ephemeris files must end in an .e extension.

3. If necessary, change the Start Time, Stop Time & Step Size.
   
   
4. Optionally override the times contained in the loaded file, by selecting the appropriately named option and specifying the time of the first ephemeris point.

When you use an external propagator, STK reads the ephemeris from the external file only once, and then it stores the information internally. If you change the ephemeris file outside of STK and want to use the new information, save the ephemeris file and click the Reload Ephemeris button.