Ayan Chalan Siddhant: Precession of the Equinoxes by Birender Kumar Nautiyal

How to calculate 25771 years of the cycle, 71.59 years taken in one degree of Ayanamsha, 70.56 years taken in one day of seasonal change, 50.29 Vikala Ayanamsha of one year etc. Apart from this, the difference between Ishtayears and Ganayears has also been explained in this chapter. In the fourth chapter of the preliminary calculation part, the method of making the ayan motion wheel has also been explained in detail so that if you first make the instrument then it will be easy to take any kind of decitropical. In the fifth chapter of Dwaparyugant Gananat Part, it is given in detail how many cycles passed from Satyayug to the end of Dwaparyug. The calculation of how many days of seasonal change or how much Ayanamsha had passed during the end of Dwaparyug is also given in detail. In the sixth chapter of Dwaparayugant Ganana part, the twelve Sidereal solsticess of the last day of Dwaparayug have been given. On which date did the Sidereal solsticess occur during that period? In the seventh chapter of the Dwaparayugant calculation part, the twelve Tropical solstices of the last day of Dwaparayuga, the Sidereal month and the constellation movement in the stable zodiac cycle have been given.
In the second edition, this book has been divided into four parts, which have a total of 31 chapters. Therefore, writing everything in detail in the book context would increase the size of the book. Therefore, I will say in brief, detailed calculations have been done regarding the ecliptic and the precestropical. By calculating at what degrees the perihelion and aphelion occur, it can be known by which 2 months will increase or decrease in the years of a cycle. This will be useful in calculating the Kshayamas.
Apart from this, Vikrami Era, Shaka Era and AD started after how many years of Kali Yuga had passed. On the day when Ayanamsha was again at zero point, how many years of Vikrami Era, Shaka Era and AD had passed in that Kaliyug.
At present we use the eras like Vikrami, Shaka and AD, how can we use their same pattern in any period, this is also given in simple language, because on calculation before any era, there is a difference in the months of change of seasons, hence priority has been given to using the pattern. The era formation calculation is based on the Sun, Sun is always there and will always be there, hence the pattern was thought of.
Apart from this, the calculation of the date of the end of Dwaparyug or the beginning of Kaliyug has been given in which Vikrami, Shaka or AD model, including the entry month and year. The most pleasant chapter is KaliEra Nirnaya. The calculation of which date or which Vikrami Era month and entry should be considered as the beginning of Kalinav Era in the present times has been given in detail.
on which Sidereal solsticess were or are occurring at the end of Dwaparyug and at present has also been given in detail. The method of bringing the beginning of Kaliyug to 17/18 February BC has also been given in this book. Apart from this, other researches have also been given to confirm the research on Ayanamsha and seasonal change.
Sidereal is fixed and Tropical is Moviable, hence the angular distance from zero of Sidereal Aries to zero of Tropical Aries is called Ayanamsha. In the upcoming chapters, calculation of Ayanamsha, seasonal changes, solar months, Entries, day through Ahargan, date, Sidereal and Tropical Sun etc. is being given in detail, but before that it is necessary to understand the method of decimal calculation in brief.

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