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

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parallax in latitude, so that it is a variable. We are to
make a correction for this variability, both in the com-
putation of Sthiti-khanda, Bhuja and Iṣṭa-kāla. The
formula for the Sthiti-khanda is √(R+r)² - β² / (m₁ - s₁) where β
is the latitude of the Moon at the moment of conjunction.
The value of MN at the moment of conjunction will not
be equal to its value at any intermediate point because
parallax in latitude differs from position to position of the
Moon. In other words β is variable. The formulae given
for the rectification of the Bhuja B or the Iṣṭakāla I are
B' = (B × T') / T and I' = T' - √(R+r - g)² - β² / (m₁ - s₁) × T / T' where
T' is the Sthiti-khanda rectified for the variability of β,
B' is the Bhuja rectified for the same whereas T and B are
the values of the Sthiti-khanda and Bhuja computed
taking the effect of parallax in longitude above.
The effect of parallax in longitude is to prepone or
postpone the moment of first contact as well as that of
conjunction. The verse under commentary uses two terms
Sphuta-Sthiti-khanda and Sphuteshuja-Sthiti-khanda.
The former is the Sthiti-khanda rectified for parallax in
longitude whereas the latter is that rectified for parallax
in latitude ie. by adopting β' instead of β in the formula
√(R+r² - β²) / (m₁ - s₁) where β' = β ± effect of parallax in latitude.
Suppose on account of parallax in longitude the
moment of first contact t₁ becomes t₁ + δt₁, and let the
moment of conjunction t₂ become t₂ + δt₂. Then the
Sthitikhanda unrectified for parallax in longitude will
be (t₂ - t₁) whereas that rectified for parallax will be (t₂ - t₁)

• (δt₂ - δt₁). This rectified Sthitikhanda is called
  Sphuta-Sthiti-khanda. Now the verse under commentary
  gives a procedure to rectify the Bhuja, and Iṣṭakāla in the