Computation of Azimuth and Elevation George H. Born.
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These slides describe how to convert a spacecraft vector, , in ECEF or ECI coordinates to Azimuth and Elevation given geocentric latitude, east longitude, and height above the ellipsoid of a tracking station. ECEF coordinates are considered first.
ECEF vector of spacecraft
Station location ( , , H)
Height above ellipsoid
1) Compute in the ECEF ( , , ) frame
and are the equatorial radius and flattening respectively of the reference ellipsoid
2) Compute in ECEF coordinates
3) Now convert to coordinates
To get replace with the coordinates of .
4) Compute Azimuth, , and Elevation, .
Now proceed with step 1.
The value of at any UTC can be obtained by inserting a satellite into a scenario in STK. Set the orbit epoch and start time to the desired UTC, set the longitude of the ascending node to 0.0° and click the apply button. Then choose right ascention of the ascending node (RAAN). This will be the value of for the chosen time. Of course, one can also compute the Azimuth and Elevation in STK.
For example, at universal time coordinated, UTC, JAN 1, 2008, 0 h, 0 m, 0 sec, .