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

469 finding the Sphutakrānti (ie. modern declination) of the planet. The Krānti of the planet or the declination of the foot of the latitude of the planet added to the latitude rectified called Sphuṭasāra, gives what is called Spaṣṭakrānti of the planet and its Hsine is called Spaṣṭa-Krāntijyā. From this H sin δ, H cos δ etc. is to be computed (as mentioned in Triprasnādhikāra in the context of finding the zenith- distance of the Sun). From the time that has elapsed after the rise of the planet called the Unnata, the shadow is to be computed as in the case of the Sun’s shadow. Having thus computed the shadow or what is the same the zenith-distance of the Moon or that of the stars, the instru- ment called Nalaka could be pointed to the spot where that celestial body is situated. Comm. The words Krānti, Spaṣṭakrānti were explained before. Also the method of calculating the zenith-distance from a knowledge of the declination was described before in Triprasnādhikāra. Verses 14, 15. Consideration of horizontal parallax in the case of visibility of the Moon or planets. H cos z or what is called the Mahāśaṅku of the Moon or planet is to be reduced by 1/15th of the respective daily motion gives the visible Sanku when the radius is taken to be 3438. If the radius is taken as 120, 1/450th of the daily motion is to be subtracted. If H cos z is less than 1/15th (or 1/450th) of the daily motion, then the Moon is not visible. This applies to the other planets as well, but as this is a neglible matter, [the earlier Āchāryas did not suggest this. Comm. In the context of the subject of parallax, we mentioned that in the case of the Moon, the horizontal parallax happens to be 1/15 of the Moon’s daily motion