Ayanamsa

From the Hindu ayana, the arc that describes the increasing gap between the tropical and sidereal zodiacs. The ayanamsa, which changes continually at the rate of approximately 50″ a year, is currently about 24.2°. To convert tropical measurements (based upon the Sun’s Aries ingress) to sidereal measurements (based upon constellations, fixed stars) the appropriate ayanamsa is subtracted from the tropical position,