Greenwich hour angle

Greenwich hour angle [′gren·ich ′au̇r ¦aŋ·gəl]

(astronomy)

Angular distance west of the Greenwich celestial meridian; the arc of the celestial equator, or the angle at the celestial pole, between the upper branch of the Greenwich celestial meridian and the hour circle of a point on the celestial sphere, measured westward from the Greenwich celestial meridian through 360°. Abbreviated GHA.