h
hour angle
Angleexact by definition
An hour of angle is exactly 1/24 of a full turn, 15 degrees or π/12 radians. Right ascension and hour angle in astronomy are measured in hours, minutes and seconds of time rather than degrees, because the sky turns through 15 degrees every hour and a coordinate in hours can be compared directly against a clock.
Watch out: A minute of right ascension is 15 arcminutes, not one, and a second of right ascension is 15 arcseconds. Mixing time-based and arc-based subdivisions is the most common error in reading a coordinate: a position given as 12ʰ 30ᵐ is 187.5 degrees, not 12.5.
| 1 h | 15 ° |
Solvers that use angle