Astronomy is the basis for Astrology. Without knowing the coordinates of Grahas in the sky, how could one practice Astrology? Among the six Vedangas, Jyotisha occupies an honourable place, and it includes both Astronomy and Astrology. Like the classical texts of Jyotisha state, the corpus of the subject is made up of Ganita, Samhita and Hora. The Ganita is the astronomical part of Jyotisha, also called Siddhanta.
The Maharshis and Acharyas of yoga computed the Graha positions for ascertaining the auspicious and inauspicious times for the performance of important activities such as Yajnas. The important events, such as the birth of Kings and princes, were recorded in terms of Graha positions at birth. We can find such evidence in Ramayana, which contains the Janmakundali of Shri Rama and his brothers. Similarly, we find numerous references to Graha positions in Ramayana, Mahabharata and Puranas, such as the movement of Grahas through Rashis and Nakshatras, the commencement of a year, Eclipses, etc., that requires advanced mathematics and astronomy.
If you are curious about how our ancients computed the planetary positions, this book is for you. The book covers the Graha computations based on both Modern and Siddhanta approaches. This book is essential for all true seekers of Jyotisha because, in the absence of Siddhanta (Ganita), there is no Samhita and Hora.