An exclamation denoting surprise, joy, or grief. Both as uttered and as written, it expresses a great variety of emotions, determined by the tone or the context. When repeated, ha, ha, it is an expression of laughter, satisfaction, or triumph, sometimes of derisive laughter; or sometimes it is equivalent to "Well, it is so."
source: Webster 1913
(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