lookangle

Lookangle, in the context of navigation, astronomy, and telecommunications, is the angle between an observer’s local horizon and the line of sight to a target. It is typically described by two components: azimuth and elevation. The azimuth is the compass direction to the target projected on the horizontal plane, usually measured clockwise from true north. The elevation is the angle above the local horizon, ranging from 0 degrees at the horizon to 90 degrees at the zenith.

In practice, look angles are used to point sensors and antennas toward a target such as a satellite, star, planet, or spacecraft. For satellite ground stations, the antenna is steered in azimuth to the given azimuth angle and pitched in elevation to the elevation angle, so the antenna line of sight aligns with the satellite’s position.

Calculation typically requires the observer’s position (latitude, longitude, altitude) and the target’s position (which may be provided as right ascension and declination for celestial objects or as orbital elements for satellites). These coordinates are transformed into the local horizon frame to yield the current azimuth and elevation. Tracking requires updates over time to account for the target’s motion, with refinements for parallax, atmospheric refraction, and local observer motion if relevant.

Applications of lookangle include satellite tracking, radio link budgeting, astronomical observing, and other line-of-sight targeting tasks. Accuracy depends on the quality of the target’s positional data and timing, and is more sensitive at low elevations due to atmospheric refraction and line-of-sight distortions.