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

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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