सिद्धान्तशिरोमणि: गणिताध्याय (भास्कराचार्य - ग्रहगणित, मध्यमाधिकार व स्पष्टाधिकार सटीक)

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beginning of the Madhyādhikāra, Bhagaṇādhyaya in verses
1 to 6. Even Bhāskara gave such a proof as appealed to
Āgama ie. 'Authority', which proof therefore will not be
acceptable to a student of Modern Astronomy, who is likely
to question how the Āgama came into existence.
How the Āgama came to formulate the number of
sidereal revolutions of the grahas, we shall now see.
The forefathers of Hindu Astronomy (have been re-
ported to be eighteen in number in the famous verses " सूर्यः
पितामहो व्यासो वसिष्ठोऽत्रिः पराशरः कश्यपो नारदो गर्गो मरीचिर्मनु-
रङ्गिराः लोमशः पौलिशश्चैव च्यवनो यवनो भृगुः, शौनकोऽष्टादशैतेस्युः
ज्योतिषशास्त्रप्रवर्तकाः " Of these Brahmagupta mentions
Brahma-Siddhānta, which he reports to have resuscitated.
Varāha Mihira gave a version of the old Sūryasiddhānta,
mentioning that it accorded with observations. Āryabhata
says that he revived his system from the then existing
ocean of knowledge both good and spurious. The fact that
none of these outstanding astronomers mentioned that
they had derived their systems from a foreign source, and
the reasonableness in presuming that all these three could
not be impostors, make the author of this work feel
strongly that there should have been some works in the
name of Āgamas extant long before these Acharyās. The
argument that the crude Vedānga-jyotiṣa alone should
have existed before Āryabhata, simply because, no other
work worth the name has been discovered, may not be
correct. It is quite possible that crude works could exist
side by side with advanced scientific works, just as even
nowadays we have thinkers and works of a primitive type
existing along with highly advanced thinkers as well as
scientific works).
Bhagaṇopapatti. In the first place, the forefathers of
Hindu Astronomy must have noticed very easily that the
Moon has a motion among stars, for, this could be detected