Chain: Event Data

Reports certain data at defined event times during each interval, for strands consisting of only two objects. The 'From-object' is the first object listed in the strand; the 'To-object' is the second object listed. Values are reported for each strand access interval that lies within the requested report intervals. The azimuth and elevation angles are reported with respect to a frame determined by the first object. The azimuth angle is the angle from the X axis (positive about the Z-axis) to the projection of the apparent relative position vector into the XY plane. The elevation is the angle of the apparent relative position vector from the XY plane, with positive angles being used when the vector has a negative Z component. When the first object is a Facility, Place, or Target, the XYZ frame is Topocentric (X aligned with North, Y aligned with East, and Z aligned with the detic nadir of the detic subpoint of the first object with respect to its central body). When the first object is a Satellite, Missile, or LaunchVehicle, the XYZ frame is CbiVVLH (inertial vehicle velocity local horizontal frame, with the Z axis aligned with the anti-radial direction and the X axis constrained toward the inertial velocity direction). When the first object is an Aircraft, GroundVehicle, or Ship, the XYZ frame is CbfVVLH (fixed vehicle velocity local horizontal frame, with the Z axis aligned with the anti-radial direction and the X axis constrained toward the central body fixed velocity direction) when the central body fixed velocity is not close to zero; when the velocity is close to zero, then the Topocentric frame is used. When the first object is a Sensor, then the frame is determined by its parent object as described above.

Type: Interval data

Availability: Reports

Name Description
AOS The event time is the start time of the interval (a.k.a. acquisition of signal).
LOS The event time is the end time of the interval (a.k.a. loss of signal).
TME The event time is the time of maximum elevation during the interval.
TCA The event time is the time of closest approach (i.e., minimum range) during the interval.

STK Programming Interface 11.0.1