Setting of a Celestial Body

an astronomical phenomenon caused by the diurnal rotation of the earth on its axis; the moment when a celestial body crosses the hozizon in its transit to the invisible half of the celestial sphere below the horizon. The moments of the setting of a celestial body and the azimuth of the point of setting are determined by the same formulas as for the rising, but of the two values of t and A, 0° < t < 180° and 180° <A < 360° are selected.