Jyotihshastra: Astral and Mathematical Literature c4.s2.21

c4.s2.21

Āryabhaṭa wrote a second work that formed the basis of the Ardharātrikapakṣa, apparently entitled Āryabhaṭasiddhānta. This is now lost, though a number of astronomers have mentioned its views, and some commentators—especially on the Sūryasiddhānta—have quoted its verses.⁴¹ Especially prevalent in these quotations are verses describing Āryabhaṭa’s simple and crude observational instruments (e.g., by Mallikārjuna Sūri⁴² and by Tammayajvan⁴³) and his clepsydras (by Tammayajvan and by Rāmakṛṣṇa). The first treatise to follow the Ārdharātrikapakṣa of the Āryabhaṭasiddhānta was a revised version of the Sūryasiddhānta. This was composed by a pupil of Āryabhaṭa named Lāṭadeva⁴⁴ according to the information available to Al-Bīrūnī; and there is no good reason to doubt this attribution. As summarized by Varāhamihira in the PS it is a karaṇa rather than a siddhānta; its epoch is midnight 20/21 March 505. It is nuclear whether this form is that of Lāṭadeva’s original, or was imposed on it by Varāhamihira.