Local Hour Angle (LHA)

Local Hour Angle is the angular distance of a body’s meridian measured westward from the observer’s meridian, 0 to 360 degrees. It is found from the almanac by LHA equals GHA minus west longitude, or GHA plus east longitude, adding or subtracting 360 to stay in range. In sight reduction with HO 229 or HO 249 the assumed longitude is chosen so LHA is a whole degree, a table entry. In the astronomical triangle LHA is the angle at the elevated pole, between the observer’s meridian and the body, one of the three inputs that yield the computed altitude and azimuth.