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

385 [चित्र: Fig. 83 — Equator, Ecliptic, Prime vertical] Fig. 83 Note 1. Bhāskara says PB' (fig. 82) is Krānti-Sinjanī; so it is because PB' = PK' sin (90 - λ) = (H sin ω H cos λ) / R = H sine of the declination of a point whose longitude is 90 + λ = Satribha-grahaja-krānti as is mentioned by Bhāskara and Sūrya-siddhānta. Note 2. If M be the centre of the Moon's disc and ABC its horizon defined above, the arc AB intercepted between the Ecliptic and the Equator is Āyana Valana, the arc BC intercepted between the Equator and the prime- vertical is Ākṣa Valana and the arc AC intercepted between the Ecliptic and the prime-vertical is Sphuta- Valana. Note 3. The analysis of Ākṣa Valana proceeds on similar lines, only we have P and N in the place of K and P. Note 4. The mistake of Lallāchārya alluded to by Bhāskara is as follows. The Āyana Valana, we have seen is zero at the Ayanas ie. the solstices and maximum at ♈ and ♎ ie. the equincotial points removed by 90° from the Ayanas. Now Hversine = R — H cosine so that when 90 — λ = 0 ie. λ = 90°, Hversine (90 — λ) = R — H cos (90 — λ) = R — H sin 90° = R — R = 0 and when 90 — λ = 90° ie. 49