Question

what is the purpose of cross range, down range and vertical (CDV) coordinate systems.

Answer 1

The Horizontal coordinare system is fixed • to a location on Earth, not the stars. The refore, the altitude & azimuth of an object in the sky changes with time as the obj eat appears to drift across the sky with Earth's rotation. In addition, since: the horizontal system is dessed by the observer's local borizon , the same objeet Viewed from difperent locations on earth at the same time will have , dipperent values of all teede & azimuth. Horizontal coordinates are very we pulifer determining the rise if set times or an object in the sky, when an objectis altitude is o', it is on the horizen. If at that moment it's altitude is increasing, it is rising, but if its altitude is decreasing it is setting. However, all objets on the celestial sphere are subject to diurnal motion, which always appears to be westcoard