Function Rotation_EQD_HOR

Rotation_EQD_HOR(time: FlexibleDateTime, observer: Observer): RotationMatrix
Calculates a rotation matrix from equatorial of-date (EQD) to horizontal (HOR).

This is one of the family of functions that returns a rotation matrix for converting from one orientation to another. Source: EQD = equatorial system, using equator of the specified date/time. Target: HOR = horizontal system.

Use HorizonFromVector to convert the return value to a traditional altitude/azimuth pair.
Parameters
- time: FlexibleDateTime
  The date and time at which the Earth's equator applies.
- observer: Observer
  A location near the Earth's mean sea level that defines the observer's horizon.
Returns RotationMatrix
A rotation matrix that converts EQD to HOR at time and for observer. The components of the horizontal vector are: x = north, y = west, z = zenith (straight up from the observer). These components are chosen so that the "right-hand rule" works for the vector and so that north represents the direction where azimuth = 0.