CoordinateSystem.Epoch Property

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Description

For CoordinateSystem objects built on vectors which are relative to the position of bodies that move in space over time, the Epoch property indicates the time at which the CoordinateSystem is defined or re-evaluated. The Epoch property can therefore serve as a means for updating a time-dependent coordinate system. To model a coordinate system that rotates in time, the CoordinateSystem object should be updated any time the spacecraft state is updated. Setting the Epoch property to the spacecraft (or celestial object) epoch will "re-evaluate" both the coordinate system and the underlying vectors used to build the coordinate system for the "current" epoch. Therefore, the user should add a line inside the control loop of the script to synchronize the Coordinate System with the Spacecraft, such as CoordinateSystem1.Epoch = Spacecraft1.Epoch; The Epoch property can also be set to a time, in GSFC MJD Format.

 

Timing Precision Mode

This page describes functionality in millisecond timing precision mode. Millisecond timing precision mode is deprecated and will be removed in a future release. We recommend that you migrate your Mission Plans to nanosecond timing precision mode.

Click here to see the documentation for this object in nanosecond timing precision mode.

 

Attributes

Type:

number

Access:

read/write

Units:

day

Default Value:

"Undefined"

 

Syntax

myVariable1 = myCoordinateSystem1.Epoch;

 

myCoordinateSystem1.Epoch = myVariable1;

 

See also

CoordinateSystem Object

Vectors and Coordinate Systems Guide

Orbit Reference Frames Guide

Attitude Reference Frames Guide

Matrix, Array, and Variable Math Guide