ब्राह्मस्फुटसिद्धान्त (ब्रह्मगुप्त - शून्य, कुट्टक, बीजगणित एवं सम्पूर्ण २१ अध्याय सान्वय सटीक)

MODERN SŪRYA SIDDHĀNTA 69 Chapter Name of the Number Chapter of verses Subject XIII Vyatīpāta-viṣayāḥ 26 Armillary sphere and astronomical instru- ments XIV — 28 Modes of reckoning time Total 500 From the contents of the Modern Sūryasiddhānta, it appe- ars that its great author (or rather compiler, since this Siddhānta has been existing much before he compiled this treatise) intends giving a complete but brief account of the entire Indian astron- omy. He has been careful enough to avoid controversies, and he has omitted the methods occurring in other Siddhāntas and Mahā-tantras as alternative rules. He describes only those which are most important and of general nature. Part II of the book dealing with cosmogony and geography etc.. is very brief , a nd the entire subject has been summarised in three chap- ters (Chapters XII to XIV). The Chapter on Astronomical instruments (XIII) is sketchy and rather incomplete; the author has given the names only of the instruments, as if the purpose was to keep the details secret and guarded. The whole text of the Sūryasiddhānta is finished in 500 verses (compare this with the length of other Indian books on Astronomy: the Brāhmasph- uṭasiddhānta 1008 verses, the Siddhānta-śekhara 890 verses and Siddhānta-śiromaṇi proper 962 verses). The Modern Sūryasiddhānta is a composition or compila- tion of a period when the Āryabhaṭīyam and the Brāhmasphuṭa- siddhānta had already become popular. This Sūryasiddhānta is indebted to both these systems, though it has nowhere acknowledged them in the Text. We shall refer to this matter later at an appro- priate stage of our discussion. It may casually be mentioned here that Alberuni has ascribed the authorship of the Sūryasiddhānta to Lāṭadeva while Munīśvara (603 A. D.) has ascribed it to Āryabhaṭa I. Though there is little or no support to these views, it is not improbable, that the works of Āryabhaṭa I and Lāṭadeva which followed mid- night-day-reckoning were based on the Sūryasiddhānta prevalent at the time. P. C. Senagupta on the other hand is of the opinion that “ the old Sūryasiddhānta was made up-to-date by Varāhami- hira by replacing the old constants in it by new ones from Ārya-