Book describes the astronomical aspects useful in Vedic Astrology and the mathematical calculations needed for making the horoscopic chart and the divisional charts. Indian concepts and the units of time have also been discussed. Calculation of Lagna for birth anywhere in the world. Issues relating to different Ayanamshas. Panchanaga features explained. Units of Time in Indian system. Astronomy related to Astrology. S. Tyagarajan: He was an officer of the Armed Forces Headquarters Civil Services. He has been a Faculty member with the ICAS for nearly two decades. He has been one of the founding members of the Jyotisha classes of ICAS started at Sri Devi Kamakshi Mandir in Delhi in the year 2000. ICAS, in recognition of his vast contribution to the teaching of Jyotisha has conferred on him several titles. At present he works as Deputy Controller of Examinations, Indian Council of Astrological Sciences (ICAS).