The Great Jupiter Saturn Perturbation. ( Amplitude 2783 sec, Duration, Laplace Period = 918 years )
The English Era + 3102 gives the Kali Era, the Era of the Vedic Calender. Add 3102 to the Year of Birth to get the Kali Year of Birth. From that value 4660 is deducted and the value is divided by 918. This gives the Beeja Kendra. Find out the Sin ( Bhuja ) of that, multiply it with 2783 seconds and add it to Saturn’s longitude if the Kendra is in NCH and subtract it if it is in SCH.
The differential equation for that is
If Kali Year of birth is xyear
m = 2783 secs*( Sin ( xyear -4660) * 360/918)
If m is in SCH, M = M – m
If m is in NCH, M = M +m , where M is the Mean Longitude of Saturn