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

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elapsed after the Saṃkramaṇa day (ie. the day on which
the Sun has left one Rāśi and entered another); obtain
the hour-angle in nāḍīs of the Sun at the ending moment
of the Amāvāsyā ie. at the moment of New Moon; add or
subtract one-fourth thereof in Rāśis from the position of
the Sun according as the Sun is in the Western or Eastern
hemisphere; then finding the declination of that point
and from the sum or difference of the declination and
latitude of the place, obtain the zenith-distance of the
culminating point of the ecliptic; taking that point to be
roughly the Vitribha ie. the point of the ecliptic which is
90° behind the Sun on the ecliptic, find one-sixth of the
zenith-distance; taking the sum or difference of the result
and the longitude of the Sun with respect to the node (got
in the beginning by adding half a Rāśi to his position at
full-Moon) if the result happens to fall short of 7°, then
we could expect a solar eclipse.
If there be no eclipse at the current New Moon, then
go on adding 1 Rāśi - 0° - 40′ - 15″ to the longitude of
the Sun with respect to the Node (which will be his longi-
tude for the moment of the next New Moon) and repeating
the procedure indicated, the occurence of an eclipse or
otherwise could be known. If occurence be indicated then
compute the actual positions of the Sun, Moon and Rāhu
and following the procedure to be indicated in the chapter
on solar eclipses, the moment of the occurence of the
eclipse and other relevant details could be computed.
Comm. In the case of a lunar eclipse, the Manaik-
yārdha ie. half the sum of the diameters of the eclipsing
and eclipsed bodies (namely the cross-section of the Earth's
shadow at the lunar orbit and the Moon) is 56′. This is
the maximum limit to the celestial latitude of the Moon
if an eclipse were to occur, and this latitude will be there
if the longitude of the Moon with respect to the nearer node
is 12°. Since a lunar eclipse occurs at the moment of a full
Moon, the distance of the Sun then from the opposite node