Description | Example | Return Message | Group

CAT

Set properties for a Close Approach computation.

Syntax

CAT <ObjectPath> {Option}

Related Commands

Description

Use the CAT command to set the properties for a Close Approach computation. Use the CAT_RM command to compute the Close Approach. This command is valid for Satellite, LaunchVehicle and Missile only.

The following tables describe the command options.

Note: Currently, each option must be entered on a separate command line.

{Option} Description
LaunchWindow {TimeInterval} Specify the time interval during which the vehicle may initiate its trajectory.

For valid {TimeInterval} values see Time Options.
Range <Value> Specify a value corresponding to the minimum allowable distance between the reference object and any other object.

The <Value> is entered in Connect distance units, and should be greater than 0.0m.

The following table describes the Advanced options.

Advanced {Options} Description
Database "<FilePath>" Specify the satellite Database file to be used.

If you specify a database with a *.sd extension, descriptions for the close approach objects are automatically included when the object is created. If you specify a database with a *.tce extension, descriptions aren't included.

By default, CAT searches the stkAllTLE satellite database.
XRefDatabase {On | Off | "<FilePath>"} Specify a secondary database to augment that found in the standard TLE database. For example, if the SSC number of the satellite is 16609, the cross-reference feature gives you the common name 'Mir.'
Filter {FilterType} [{On | Off | <DistanceValue>}]

Using the CAT Filter command allows you to tune preliminary filters that limit the amount of ephemeris generated to compute close approaches for an object. The proper use of these preliminary filters can greatly reduce the amount of time needed for close approach processing. These pads are added to the <RangeVal> constraint specified with the CAT_RM Connect command.

{FilterType} can be:

  • OutOfDate - the <Value> is a time added to the beginning and end of the analysis period. Valid value is between 1 day and 3650 days, entered in Connect Time units.
  • ApogeePerigee - Eliminates candidate close approach objects having a range of altitude that doesn't overlap with that of the selected satellite, missile or launch vehicle.
  • OrbitPath - Eliminates any candidate object whose orbital path doesn't come within a specified distance of the orbital path of the group satellite. This filter doesn't consider the position of the satellites at specific points in time; only the paths in inertial space are used. This filter is available only for satellites and shouldn't be used if the ephemeris of the group satellite contains orbit maneuvers.
  • Time - This filter works in two stages. The first stage determines when each candidate satellite will be within a specified distance of the path (not the position on the path) of the group satellite and vice versa. The second stage determines the overlaps of these intervals. Any candidate satellite that isn't close to the trajectory of the group satellite at the same time that the group satellite is close to the candidate's trajectory is eliminated. This filter requires an accurate knowledge of the in-track motion of both satellites and is available only for an SGP4 satellite.

The default <DistanceValue> for all {FilterTypes} is 30 km, and is entered in Connect distance units.
AddThreats {On | Off} [<MaxToAdd>] This option allows satellites to be added to the scenario and, therefore, to close approach calculations. The command adds conjuncting satellites, i.e., candidate satellites that closely approach the reference vehicle, to the STK scenario when calculations are computed.

Use the <MaxToAdd> value to limit the number of Satellites added to the scenario.

If On is entered, you must specify a <MaxToAdd> value. <MaxToAdd> is an integer between 1 to 99999.
SetModelScale <Scale> Specify the model scale for Satellites added to the Scenario. Use the AddThreats option to indicate whether Satellites are added to the Scenario.

<Scale> is a real number between 0.0 and 10.0.
AccessGfx {LineState} {AnimateHighlightState} {StaticHighlightState} Set graphics that display during a close approach. All three parameters must be specified in the exact order shown here. Valid values for state parameters are On and Off.
Propagator {Routine} Choose a different implementation of the SGP4 routine for use during close approach calculations only. Different SGP4 implementations (other than the internal SGP4 routine implemented by STK) may or may not be available to you, depending on your STK install configuration. You can determine if different routines are available by creating a satellite, choosing the SGP4 propagator, and noting whether a combobox appears on the panel listing names of routines. If no combobox appears, then the only available routine is the internal routine supplied by STK.

Note: In the past, you may have used this command to choose the USGovMSGP4 routine. This is no longer necessary, as the implementation of the internal SGP4 routine and the USGov routine have been made the same.

Note: Routine names are case sensitive.

Note: When you choose a different propagator for close approach, it does NOT change the propagator used for the vehicle. The change only affects close approach functions and doesn't impact STK.

Example

To set access graphics so that close approaches are highlighted using a thick line overlaying the ground tracks and only display when you're not animating:

CAT */Missile/TestMissile AccessGfx On Off On

To set the number of candidate satellites to add to 100:

CAT */satellite/stex AddThreats On 100

To set an apogee/perigee pad of 30,000 m for the ERS1 satellite, which has a maximum range value of 5000 m:

Cat */Satellite/ERS1 Filter ApogeePerigee 30000

To set a 45 minute launch window for the TestMissile:

CAT */Missile/TestMissile LaunchWindow "1 Jan 2000 10:01:00.00" "1 Jan 2000 10:46:00.00"

To change the propagator so that the AFSPC-SPG4 routine is used during close approach calculations instead of the standard SGP4 routine:

CAT */Satellite/ERS1 Propagator AFSPC-SPG4

To use the stkAllComm.sd database as a cross-reference lookup for TLE data:

CAT */Satellite/ERS1 XRefDatabase "C:\stk\User\Database\stkAllComm.sd"

ReturnMessage

If activated, Connect returns an acknowledgement message.

Group Membership

This command belongs to the following group(s):

CAT

Version

10

STK Programming Interface 11.0.1