hour anglehour angle
Astron. the angle formed at the pole, or its arc on the celestial equator, between the hour circle of a celestial object and the observer's celestial meridian measured in hours, minutes, etc.: it represents the elapsed time since the object passed directly over the observer
The angular distance, measured westward along the celestial equator, between the celestial meridian of the observer and the hour circle passing through a celestial body.