Spacecraft Insert Options

These options enable you to set the analysis time period, the propagation step size, and TLE-related selections.

Analysis Time Period

To select a different time period than the scenario time period, enter new start and stop times. For more information on how to update the Analysis Time Period, see Scenario Time Period.

Propagation Step Size

By default, the step size is automatically determined. To set the step size, clear the Automatically determine step size check box and enter a propagation time step, in seconds.

Propagation TLE Source

In this subpanel, you can choose the satellite database source. Choose from one of the following options:

Option name	Description
Import from AGI Server	You must be connected to the internet to utilize this source.
Import from File	Browse to and select the General Perturbation (GP) data (e.g., TLE) file you want to use as the source. While OMM files in XML, KVN, and CSV formats are acceptable as the source file, the tool is restricted to using five-digit SSC numbers. STK will not list TLEs using nine-digit SSC numbers.
Use Default Satellite Database	Selecting this takes you to the default Satellite database as the source.

For this topic, the term TLE is synonymous with GP data.

You can also choose when STK should switch between GP elements by selecting one of the following options for Switching Method:

Option name	Description
Epoch	STK will switch between GP elements based on the epoch of the TLE.
Midpoint	STK will switch between GP elements based on the midpoint between two TLE epochs.
TCA	STK will switch between GP elements based on the time of closest approach (TCA). STK calculates the TCA by propagating the first and second GP elements over the time period between their respective epochs and then determining the point at which the two paths are nearest each other. This option provides the smoothest possible switch between two GP elements.

There are additional check box options in this subpanel.

Option name	Description
On propagation, automatically retrieve elements	Select this check box to allow the satellite's designated TLEs to be automatically updated from the selected source prior to each propagation.
Use out of date duration	Select this to have STK filter out any TLEs that precede the analysis start time or exceed the analysis end time by an offset duration. You can specify the offset duration in the text box next to this check box; the value defaults to 30 days.
Update SGP4 Propagator Defaults	Select this check box to apply your changes to the SGP4 propagator default settings.