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

436
(vide fig. 100) where M is the centre of the Moon and MD
the latitude of the Moon at the point of first contact
MD = MB + BD = m + BÊD where m is the semi-
diameter of the Moon's disc. But
BÊD = BEA + AÊS = CB̂E − CÂE + AÊS = P − p + s
where P and p are the parallaxes of the Moon and the Sun
and s the angular semi-diameter of the Sun. Thus in
order that a solar eclipse may be possible for some point
of the Earth, the latitude of the Moon at the moment of
conjunction must be less than P + s + m − p
= 57' + 16' + 15' = 89' approximately. The lesser the
northern latitude of the Moon at the moment of conjun-
ction, more places situated on the surface of the Earth
between C and F will have solar eclipse where F is the
sub-solar point ie. the point of the Earth which has the
Sun in the zenith at the time of conjunction. Similarly,
if the southern latitude of the Moon is less than 89' at the
moment of conjunction the places situated on the Earth
between G and F will have solar eclipse. In particular
the sub-solar point F will have solar eclipse if the latitude
of the Moon at the moment of conjunction is less than
HD ie. less than s+m ie. 33' approximately. The sub-
solar point will have no parallax, so that the terms P and p
in P+s+m−p vanish. For the other points ie. points
between F and C or G parallax will be there and the
latitude may be greater than s + m but less than
s+m+P−p to have an eclipse. A latitude of 33' corres-
ponds to a distance of (33 × 15) / 70 = 99 / 14 = 7 1°/14 of the Sun
with respect to a node. Thus if at the moment of conjun-
ction, the latitude of the Moon be less than 7°, even the
sub-solar point must have an eclipse.
Verses 15, 16, 17. To find Spars'akāla, Mokṣakāla,
Sammīlanakāla and Unmīlanakāla.