Next, the altitude and azimuth of the celestial body are computed for a selected position (assumed position or AP). This involves resolving a spherical triangle. Given the three magnitudes: local hour angle ("LHA"), observed body's declination ("dec"), and assumed latitude ("lat"), the altitude "Hc" and azimuth "Zn" must be computed. The local hour angle, "LHA", is the difference between the AP longitude and the hour angle of the observed object. It is always measured in a westerly direction from the assumed position.