Computation of planetary geocentric latitudes and declinations based on the Sūryasiddhānta algorithm

Abstract

The classical Indian astronomical text, the Sūryasiddhānta, provides a comprehensive framework for calculating the positions of celestial bodies through a set of well-defined, planet-specific procedures. While the computation of true planetary positions involves both longitudes and latitudes, each governed by distinct rules and corrections, while the determination of the true geocentric longitudes (nirayaṇa) for any given time and location was already presented in our previous study. Expanding upon that foundation, the present study addresses the computation of true geocentric latitudes and declinations of the planets, employing the algorithm outlined in the Sūryasiddhānta. The methodology is applied to calculate the planetary latitudes and declinations at the time of sunrise on March 30, 2025, for Mandi, Himachal Pradesh. The results are compared with the geocentric latitudes of the planetary data from Stellarium to evaluate the precision and reliability of the traditional algorithm, offering insights into its applicability for contemporary astronomical modeling.