(fl. between ca. a. d. 950 and 1100).
Of the personality of Āryabhaṭa II, the author of the Mahāsiddhānta (or Āyasiddhänta), virtually nothing is known. His date can be established only by his alleged dependence on Śrīdhara who wrote after Mahāvīra (fl. 850) and before Abhayadeva Süri (fl. 1050); and by his being referred to by Bhāskara II (b. 1114). He must be dated, then, between ca. 950 and 1100. Kaye’s strange theories about the two Āyabhaṭas, which would have placed Āryabhaṭa II before al-Bīrūnī (963-after 1048), have been refuted by Datta. Nothing further can be said of Āryabhaṭa II; manuscripts of his work are found in Mahārāṣṭra, Gujarat, and Bengal.
The Mahāsiddhānta (see Essay VII) consists of eighteen chapters:
1. On the mean longitudes of the planets
2. On the mean longitudes of the planets according to the (otherwise unknown) Parāśarasiddhāanta.
3. On the true longitudes of the planets.
4. On the three problems relating to diurnal motion.
5. On lunar eclipses.
6. On solar eclipses.
7. On the projection of eclipses and on the lunar crescent.
8–9. On the heliacal risings and settings of the planets.
10. On the conjunctions of the planets
11. On the conjunctions of the planets with the stars.
12. On the pātas of the sun and moon. Chapters 13–18 form a separate section entitled Golādhyāya (“On the Sphere”)
13. Questions on arithmetic, geography, and the mean longitudes of the planets.
14–15. On arithmetic and geometry.
16. On geography.
17. Shortcuts to finding the mean longitudes of the planets.
18. On algebra.
The Mahāsiddhānta was edited, with his own Sanskrit commentary, by MM. Sudhaākara Dvivedin, in Benares Sanskrit Series148–150 (Benares, 1910).
Works dealing with Āryabhaṭa II, listed chronologically, are F. Hall, “On the Ārya-Siddhānta,” in Journal of the American Oriental Society, 6 (1860), 556–559; G. R. Kaye, “Two Āryabhaṭas,” in Bibliotheca mathematica, 10 (1910), 289–292; J. F. Fleet, “The Katapayadi Notation of the Second Arya-Siddhanta,” in Journal of the Royal Asiatic Society (1912), 459–462; B . Datta, “Two Āryabhaṭas of al-Biruni,” in Bulletin of the Calcutta Mathematical Society, 17 (1926), 59–74, and “Āryabhaṭa, the Author of the Gaṇita,” ibid., 18 (1927), 5–18; Ś. B. Dīkṣita, Bhāratīya Jyotiḥśāstra (Poona, 1931; repr. from Poona, 1896), pp. 230–234.