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

505
with respect to the Sun and the Moon, holds good with
respect to occultation). In this case of occultation, we
have to rectify the time of conjunction with respect to
parallax in latitude also. For obtaining this parallax in
longitude, let the planet which is nearer the earth be
taken as the Moon and the other the Sun. But to obtain
the longitude of the Vithribha, which is necessary to
compute parallaxes in longitude and latitude, the lagna of
the moment of conjunction is to be computed from the
position of the Sun and not that of the planet assumed
to be the Sun as directed above. Having obtained the
parallax in longitude, the computed moment of conjun-
ction is to be rectified for parallax in longitude, (if
necessary by the method of successive approximation) to
obtain the actual moment of apparent conjunction ie.
occultation here. This procedure is worth-adopting only
when the occultation in question takes place above the
horizon and is observable. The north-south celestial
latitudinal distance in this case of occultation corresponds
to the celestial latitude of the Moon in the case of a solar
eclipse. The direction of this celestial latitude is to be
construed as that of the direction in which the planet near
the earth is situated with respect to the other. If the
planet which is nearer the earth happens to have a motion
lesser than that of the other, or be retrograde, then the
planet which is situated at a greater distance from the
earth will be over taking the other so that the higher
planet gets occulted in the eastern direction of its disc.
Thus the first contact is to be known to be in the east
and the last contact would be in the west; (If otherwise,
the other way).
Comm. Self-explanatory.
Here ends the Grahayutyadhikāra.
64