Spacecraft.AnnularShadowTimes(CelestialObject, TimeSpanArray, Array) Method

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Description

Determines the entry time, exit time, and duration of a Spacecraft's pass through the shadow of a central body. Events are reported for annular shadow conditions only.

 

Timing Precision Mode

This page describes functionality in nanosecond timing precision mode.

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

 

Note: This is an interval method. See the Interval Methods page for more information.

Note: This method has a state. See the Methods and Properties with State page for more information.

 

Method Signature

Spacecraft.AnnularShadowTimes(

CelestialObject celestialObject,

TimeSpanArray EventTime,

Array EventType)

 

 

Arguments

celestialObject

Description:

CelestialObject to use as the occulting body

 

 

EventTime

Description:

The time that the event occurred.

 

The FF_Preferences.IntervalEventReportingBehavior property controls whether the start of propagation is reported as an event. By default, if the time in shadow starts before the beginning of the propagation span, FreeFlyer will label the start of the propagation as the start of the time in shadow.

 

 

EventType

Description:

The type of the event that occurred. Event type == 1 is entry into annular shadow. Event type == 2 is exit from annular shadow.

 

 

 

Return Value

Type:

number

 

 

Returns the number of elements filled into EventType and EventTime arrays.

 

Syntax

myVariable1 = mySpacecraft1.AnnularShadowTimes(myCelestialObject1, myTimeSpanArray1, myArray1);

 

 

Example 1

This example demonstrates how to generate a report of a spacecraft's pass through the annular shadow of a CelestialObject.

 

Spacecraft Spacecraft1;

 

Variable i;

Variable ShadowTimes;

TimeSpanArray EventTime;

Array EventType;

String scEventType;

String scEventTime;

DataTableWindow scReport({scEventType, scEventTime});

 

// Configure the Spacecraft Orbit

Spacecraft1.Epoch = "Feb 25 2026 00:00:00.000000000".ParseCalendarDate();

Spacecraft1.X = 277985775.305651960;  

Spacecraft1.Y = -113239906.103028370;   

Spacecraft1.Z = -49478764.373642288;     

Spacecraft1.VX = .986247453;     

Spacecraft1.VY = 48.329358712;     

Spacecraft1.VZ = .907393865;

 

While (Spacecraft1.ElapsedTime < TIMESPAN(10 days));

 

      ShadowTimes = Spacecraft1.AnnularShadowTimes(Moon, EventTime, EventType);

 

      If(ShadowTimes > 0) then;

            For i = 0 to ShadowTimes -1 step 1;

                  Switch (EventType[i]);

                        Case 1:

                              scEventType = "Entry into Contact: ";

                              scEventTime = EventTime[i].ConvertToCalendarDate();

                              Update scReport;

                              Break;

                        Case 2:

                              scEventType = "Exit from Contact: ";

                              scEventTime = EventTime[i].ConvertToCalendarDate();

                              Update scReport;

                  End;

            End;

      End;

 

      Step Spacecraft1;

 

End;

 

 

Output:

 

scEventType

scEventTime

Entry into Contact:

Exit from Contact:

Feb 25 2026 00:00:00.000000000

Feb 25 2026 14:20:08.349609375

 

 

 

See also

Spacecraft Object

Spacecraft.AnnularShadowTimes

Spacecraft Propagation Guide

Coverage and Contact Analysis Guide