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

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approximately. The same is extended to the case of the
planets as well. To get the proportion in the case of
taking the radius to be 120 only instead of 3438, rule of
three is applied as follows. “If the radius be 3438, 𝑣/15
is parallax, what will it be if the radius be 120?” The
answer is
𝑣/15 × 120/3438 = 𝑣 / (3438/8) = 𝑣/430 very approximately as stated.
If H cos z be less than this 1/15 th or 1/430 th of the daily
motion, the parallax does not allow the Moon to be seen.
Bhāskara specifically talks about the Moon only because,
the earlier Āchāryas did not apply the correction of
parallax to the case of the planets, because it is not
appreciable.
Verse 16. If an operation is neglected because its
effect is not appreciable, or is not of much use, or because
it is apparent, or if it implies great labour, or again if
it implies a lot of exposition that would make the text
unduly voluminous, ignoring the necessity of that oper-
ation should not be treated as wrong.
Comm. Here Bhāskara upholds the earlier Āchāryas
not stipulating parallax in the case of planets, because it
is not appreciable.
Here ends Graha-cchāyādhikāra.