Satellite Database TLE Source

In this dialog box, 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.

If the TLE source is a file and contains TLEs for SSCs that are not listed in the satellite database file (i.e., the *.sd file), then STK will add these SSCs to the results table. This enables you to choose any SSC in a TLE file, whether or not the satellite database file has an entry for it.

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 dialog box.

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.
Filter search results by TLE availability	STK defaults to selecting this check box, so if there is not a TLE associated with an SSC number meeting the search criteria, then that object does not appear in the results table. You can clear the check box so that STK will list these objects. You cannot create a satellite for an object with no TLEs.
Use out of date duration	Select this to have STK filter out any TLEs that precede the analysis start time or exceed the analysis end time by an offset duration.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.