Did you ever run across an STK word you didn't know? Then check out our growing list of common terms in STK. Please contact support@agi.com if you'd like to add more items to the list, and please reference this FAQ when you do.
Access is the term used in STK for the intervisibility calculation. You can also refer to it as "contact time," "passes," or "collection interval." An access is defined by the calculated intervisibility between two objects: a primary object and an associated object.
Area Target is an area on a central body defined by a closed loop of points. You can insert precomputed area targets for countries, states, or from a custom Shapefile.
Chain is an object like an actual chain, linking related items. In this case, it refers to a set of objects, either individual or grouped into
constellations, in order of access. Order matters, and you don't want any breaks in your chain!
Constellation is group or set of related objects, such as a group of facilities, satellites, or sensors. Grouping objects into constellations enables you to perform analysis on many objects simultaneously.
Data Provider is a container that stores data specific to a topic, use-case, capability, or tool. For example, the Model Area data provider contains a scalar called Area that holds the data computed by the
Area Tool. A data provider can also contain one or more groups, which act as folders to further classify data. As an example, the Angles data provider has a group for each built-in and user-defined angle in STK's
Analysis Workbench capability that the parent object also has. Some data providers require your input, so-called predata. These providers generally include "choose" in their names, such as Vector Choose Axes, where you provide the axes you want to express the chosen vector in.
Deck Access is a term used in STK for intervisibility calculations from one object to a set of objects not loaded in the scenario. For example, Deck Access is useful for computing visibility from a target satellite to the entire satellite database.
Detic and Centric: Many data providers in STK have so-called "detic" and "centric" versions. The most common are latitude, longitude, and altitude (LLA). STK performs centric calculations by drawing a line from the center of the Earth to the object. It then calculates LLA from the point where this line intersects Earth's surface. STK performs detic calculations by finding the closest point on the Earth's ellipsoid to the object.
Epoch refers to an instant in time. For example, a satellite's orbit epoch is the time at which the initial orbital elements you enter are true.
Scenario: In STK, a scenario is the container and setting for all of your analyses. A scenario brings your objects together with STK's powerful animation and analysis tools, enabling you to perform complex analyses and trade studies.
Simplified General Perturbations (SGP4) Propagator creates ephemeris for a satellite's future state using one or more
two-line mean element files (TLEs).
Space Surveillance Catalog (SSC) Number: The U.S. Strategic Command (USSTRATCOM) keeps track of thousands of active space objects and hundreds of thousands of inactive objects. These objects constitute the space object catalog. While most of the catalog is available to the public, some information is restricted. AGI provides the publicly released information for use with STK in the form of satellite database files and TLEs.
STK Data Federate (SDF) is a data management system that enables your engineers to share, collaborate on, and reuse your STK data across your teams and organizations.
STK Vector Geometry Tool (VGT) is a tool within
Analysis Workbench that enables you to create points, vectors, planes, axes, and systems for analysis elsewhere in STK.
Two-Line Element (TLE) File is a compact text file format that represents the state of a satellite at a given epoch. TLEs are created through real-world observations by organizations like NORAD, and distributed by organizations like
CelesTrack.
