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

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In fig. 91, EMS is called Garbha-Sūtra whereas AS
is called Dṛṣṭi-Sūtra. दृक्सूत्रात् लम्बितश्चन्द्रः तेन तल्लम्बनं
स्मृतम् ie. In as much as the Moon is depressed from the
Dṛk-Sūtra, so this phenomenon goes by the name Lambana.
It will be noted that in Hindu Astronomy geocentric
parallax will not be treated separately for the Moon and
the Sun but dealt with simultaneously as it is called for,
in the context of a solar eclipse. They were interested
in knowing the relative depression of the Moon with
respect to the Sun rather than knowing the separate
magnitudes with respect to the Moon and Sun, for which
they had no application.
'दृग्गर्भसूत्रयोरैक्यात् खमध्ये नास्ति लम्बनम्' ie. In as much
as the Garbha-Sūtra and Dṛk-Sūtra are identical in the
direction EAZ (fig. 91) there is no parallax at the zenith.
Now consider the plane through ZV of fig. 92. Suppose
the EMS of fig. 91 is in the direction EV. Then both
the Sun and the Moon may be considered to have the
same Vitribha at that moment of conjunction. Both the
Sun and the Moon being then depressed along ZV, to V'
and V'' respectively the Ecliptic will then be a circle
parallel to VA (fig. 92) through V' and the orbit of the
Moon will be another circle parallel to VA through V'', V''
being below V'. If we neglect, for a moment, the depres-
sion of the Sun, and consider VD to be the Ecliptic on
which the Sun is situated undeflected, and BC to be the
deflected orbit of the Moon relative to the Sun, then VB
is the Nati of the Moon, which will be the same distance
between VD and BC, ie. the orbits of the Sun and the
Moon.
This fact was proved by us analytically in the modern
way showing that CD = BV.
This Nati it is that influences the latitude of the Moon,
which may cause apparent conjunction when there is no geo-
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