1. The angular distance along the celestial equator from the observer's meridian to the hour circle of a given celestial body
   "The astronomer calculated the hour angle of the star"
    
2. (astronomy) the angular distance of a celestial point measured westward along the celestial equator from the zenith crossing; the right ascension for an observer at a particular location and time of day
   "Astronomers used the hour angle to track the star's position";
   - HA

Derived forms: hour angles

Type of: angular distance, distance

Encyclopedia: Hour angle