Once every 25,800 years or so, the starting points of the sidereal and tropical zodiacs coincide. After this coincidence, these points will separate from each other by the above mentioned approximate 1 degree of arc for each subsequent 72 years. The distance between the starting points of the sidereal and tropical zodiacs at any given time is known as the “Ayanamsa” There are some controversies over the year in which the starting point of the two zodiacs last coincided, which makes the determination of the ayanamsa one of Jyotish’s major confusion. This confusion has remained so and will continue to be unresolved. The most widely used ayanamsa is known as Lahari or Chitra ayanamsa. I have seen good results using Lahari and I would suggest the same for my students to start with. Maybe in due course of time, there can be research that could be undertaken using other ayanamsas.