Attitude Data File Options | STK Ephemeris and STK Binary Ephemeris Data File Options | SPICE Ephemeris Data File Options | CCSDS Data File Options | PropDef Data File Options
Export Ephemeris/Attitude Data
In the Ansys Systems Tool Kit® (STK®) application, you can create vehicle attitude or ephemeris data for all types of vehicles using the Export Ephemeris/Attitude tool. To open the Export Ephemeris/Attitude tool, select Export and then Ephemeris/Attitude... from the Utilities menu.
To create vehicle attitude or ephemeris data, click to select the vehicle from which you are creating the data file. Then fill out the rest of the Create Data File dialog box by selecting one of the following combinations:
| External STK File Type Option | Ephemeris Type Option | Click the Export File button to create... |
|---|---|---|
| Attitude | n/a |
An attitude profile ASCII text file (.a) for the vehicle. For descriptions of settable file parameters, see Attitude Data File Options. |
| Ephemeris | STK Ephemeris |
An ephemeris ASCII text file(.e) that contains ephemeris points for the vehicle. For descriptions of settable file parameters, see STK Ephemeris and STK Binary Ephemeris Data File Options. |
| Ephemeris | SpiceEphemeris |
An ASCII text file (.bsp) that contains ephemeris points for the vehicle in a format compatible with the SPICE Toolkit. For information on how SPICE files are automatically loaded by the STK application, click here. For descriptions of settable file parameters, see SPICE Ephemeris Data File Options. |
| Ephemeris | CCSDS Ephemeris |
An ASCII text file (*.oem or *.xml) that contains ephemeris points for the vehicle in the CCSDS Orbit Ephemeris Message version 1.0 format. For descriptions of settable file parameters, see CCSDS Data File Options. |
| Ephemeris | CCSDS v2.0 Ephemeris |
An ASCII text file (*.oem or *.xml) that contains ephemeris points for the vehicle in the CCSDS Orbit Ephemeris Message 2.0 format. For descriptions of settable file parameters, see CCSDS Data File Options. |
| Ephemeris | CCSDS v3.0 Ephemeris |
An ASCII text file (*.oem or *.xml) that contains ephemeris points for the vehicle in the CCSDS Orbit Ephemeris Message 2.0 format. For descriptions of settable file parameters, see CCSDS Data File Options. |
| Ephemeris | STK Binary Ephemeris |
A binary text file (.be) that contains ephemeris points for the vehicle. For descriptions of settable file parameters, see STK Ephemeris and STK Binary Ephemeris Data File Options. |
| PropDef | n/a | An ASCII text file (.pg) that contains an element set and path definition for a vehicle. For descriptions of settable file parameters, see PropDef Data File Options. |
Attitude data file options
| Option | Value |
|---|---|
| Coordinate Axes | Select from the drop-down menu the coordinate axes for the STK software to use in the file. The choices are dependent on the selected format. The Current format supports Fixed, J2000, ICRF, or Custom for the Earth, and Fixed, J2000, ICRF, Inertial, or Custom for all other central bodies. For Custom coordinate axes, click to define the coordinate system. |
| Include | Choose the details to include in the data file: either Quaternions or Quaternions and Angular Velocity. |
| Format | Provides the option to generate files compatible with prior versions of the STK application. Choose from the following options: Current, 8.0 Format, 6.0 Format, and 4.3 Format.
All supported formats may be read into the current version of the STK application. |
| Time Period | Select one of the following:
|
| Steps | Select one of the following:
|
| Output File | Enter the name of the file you are creating. The default is the name of the object. |
STK Ephemeris and STK Binary Ephemeris data file options
| Option | Value |
|---|---|
| Coordinate | This is the coordinate system in which to export the ephemeris. The choices provided depend on the selection of the central body. When the central body is Earth or Moon, there are choices in addition to the standard set of Fixed, J2000, ICRF, TrueOfDate, and Inertial: TEMEOfDate and several ITRFYYYY frames for Earth, and MeanEarth for Moon. When the central body is Earth or Sun, Inertial is not available because the inertial frame for these bodies is simply ICRF, which is already there. |
| Central Body | The location of the selected central body serves as the origin of the coordinate system in which to export the ephemeris. Selecting the Use Vehicle Central Body check box sets the central body selector to the vehicle's central body. |
| Include Interpolation Boundaries | Select this check box to include interpolation boundaries. |
| Version Format | Provides the option to generate files compatible with prior versions of the STK application. Choose from the following options: Current, 8.0 Format, 6.2 Format, 4.3 Format, 4.2 Format, and 4.1.0 Format.
|
| Export Covariance | Choose to export no covariance information, position covariance (3x3), or — for STK 6.2 or greater format — position/velocity covariance (6x6). If the requested covariance information is not available from the selected object, STK software will still create the ephemeris file but will display a warning in the Message Viewer window. Covariance information may be available for objects with paths defined using the HPOP or STK External propagators. |
| Time Period | Select one of the following:
|
| Steps | Select one of the following:
|
| Output File | Enter the name of the file you are creating. The default is the name of the object. |
SPICE Ephemeris data file options
| Option | Value |
|---|---|
| Coordinate | You may not edit the coordinate system for a SPICE propagator. |
| Central Body | Select the Use Vehicle Central Body check box or choose a central body from the drop-down menu. |
| Satellite ID | Enter the identifying number for the satellite ephemeris being created. |
| Interpolation Type | Choose the interpolation type: Type 9 (LaGrangian) or Type 13 (Hermitian). |
| Interpolation | Enter an interpolation order value between 1 and 15. If the interpolation type is Type 13 (Hermitian), you are required to enter an odd interpolation order value. |
| Time Period | Select one of the following:
|
| Steps | Select one of the following:
|
| Output File | Enter the name of the file you are creating. The default is the name of the object. |
CCSDS data file version 1.0, 2.0, and 3.0 options
| Option | Value |
|---|---|
| Originator | Enter a string that specifies an identifier of the organization producing the data file. |
| Object ID | Enter a string defining the Object ID, specified as the international spacecraft designator, also known as an NSSDC identifier, which follows a YYYY-NNNA format, where YYYY is the year of the launch, NNN is the sequential launch number within that year, and A is a letter designating the specific piece from the launch. |
| Object Name | Enter a name for the Object. By recommendation of the CCSDS standard, you should use the name from the SPACEWARN Bulletin. |
| Use Satellite Center and Frame | Select to use the central body and reference frame of the selected satellite object. |
| Center | This is the location of the selected central body that serves as the origin of the coordinate system in which to export the ephemeris. |
| Reference Frame | Select from the following reference frames:
|
| Time Precision | Specify the number of digits past the decimal point used in the expression of seconds in the selected date format. Enter an integer between 0 and 10. |
| Time System | Select the desired time system. For descriptions of the available selections, see the Units of Measure page. |
| Date Format | Select a date format. YMD format is YYYY-MM-DDT:HH:mm:SS.SSS, where YYYY is the four-digit year, MM is the two-digit month, DD is the two-digit day of the month, HH is the two-digit hour, mm is the two-digit minute, and SS.SSS is a floating point representation of seconds into the minute where the precision is specified via the time precision setting. YDOY is similar except that the day of the year, DDD, replaces the month and day of month: YYYY-DDD:THH:mm:SS.SSS. |
| Ephemeris Format | Select a format, SciNotation or FloatingPoint, for representing the position and velocity information as either scientific notation or floating point notation, respectively. Scientific notation is recommended when possible, since it guarantees the number of significant digits which will be represented. |
| File Format | Select the format of the exported file, either Keyword-Value or XML. |
| Include Covariance | Include covariance data in the exported file. (Not valid for CCSDS v1.0.) |
| Include Acceleration | Include acceleration data in the exported file. (Not valid for CCSDS v1.0.) |
| Time Period | Select one of the following:
|
| Steps | Select one of the following:
|
| Classification (valid only for version 3.0 and not required) | Enter a previously agreed-upon classification of the satellite. This is an open text field. |
| Message ID (valid only for version 3.0 and not required) | Enter an ID string that identifies the originator of the message. This is an open text field. |
About the CCSDS Ephemeris
The Consultative Committee on Space Data Systems (CCSDS) orbit ephemeris message format is defined by the CCSDS Blue Book, Orbit Data Messages, CCSDS 502.0-B-1. You can download this document from https://public.ccsds.org/publications/MOIMS.aspx. The role of the CCSDS is to develop recommendations for data and information sharing standards.
When generating a CCSDS orbit ephemeris messages using the STK application, keep in mind the following:
- Center names are restricted to central bodies known to the STK application.
- Time tags will be referred to the UTC time system.
- The interpolation method and degree will be that used by the STK application.
- Separate metadata / ephemeris data sections are created to prevent interpolation across maneuvers.
PropDef Data file options
| Option | Value |
|---|---|
| Output File | Enter the name of the file to be created. The default is the name of the object. |