The Siddhāntaśiromaṇi was composed in 1150 CE by the celebrated mathematician–astronomer Bhāskarācārya. In the Grahagaṇitādhyāya part of it, most of the standard calculations and algorithms in Indian astronomy of his times are included. All these are explained in detail with commentary on the text, namely, the Vāsanābhāṣya or Mitākṣarā. This book is on this part only. All the 460 verses of this part have been translated afresh in this work. Now, it is in the Vāsanābhāṣya that the contents of the verses are expounded in detail. In addition, the detailed derivations and proofs of the statements and algorithms are presented in the upapattis. Study of the vāsanā is indispensable for understanding the methodology of, in particular, and thereby, of Indian astronomers in general. The distinct scientific method of Bhāskara (indeed of the Indian astronomical tradition in general, of which he was a leading exponent), his approach to problems and the ways to solve them, can be understood only when one goes through the commentary and understands it. It is for this reason that the Vāsanābhāṣya has been translated into English for all the verses, for the first time. Explanatory notes based on the vāsanā of Bhāskara have been provided for all the verses in modern notation, with a large number of diagrams to facilitate the understanding.The Grahagaṇitādhyāya has 12 chapters, which is divided into two volumes: Volume 1: Madhyama, Spaṣṭa, Tripraśna and Volume 2: Parvasambhava to Pāta Adhikāras. Volume 1 has three chapters—the Madhyamādhikāra, Spaṣṭādhikāra and the Tripraśnādhikāra. This volume has a comprehensive introduction and two appendices on the Indian planetary model and elements of spherical trigonometry, which make this book reasonably self-contained. Volume 2 has the nine chapters—Parvasambhava, Candragrahaṇa, Sūryagrahaṇa, Grahacchāyā, Udayāsta, Śṛṅgonnati, Grahayuti, Bhagrahayuti and the Pāta adhikāras.
