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

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divided by the difference of the daily motions of the planet
and the Sun expressed in minutes of arc if the planet is
direct in motion or divided by the sum of those daily
motions if the planet be retrograde gives the days elapsed
after rising or to elapse for the rising to take place. Again,
compute the positions of the Dṛk-graha and the Sun for the
moment thus obtained and repeat the process till the actual
moment is obtained.
Comm. Suppose the prescribed Kālāṁśas for rising
be x and suppose the Iṣṭa-Kālāṁśas are y such that y<x;
then for the planet to rise, the arc of the equator in
between the feet of the declination circles of the Sun and
the Dṛk-graha has to increase for the planet to rise which
means that this takes some more time to happen. Similarly
if y>x, the planet has already risen. The question of the
arc decreasing does not arise in this case of rising, because
the planet's position in the east is behind that of the Sun,
and in the case of a superior planet the Sun has to advance
further for the planet to rise ie. the arc has to increase and
in the case of a retrograde inferior planet also, the arc
will be increasing. In the case of an inferior planet being
direct, the arc will be decreasing no doubt, but we have
to remember that this is a case of an inferior planet setting
and not rising which we are considering. In the case of
setting, in the east, however, of the inferior planet the
moment of setting has already elapsed and thus the condi-
tion is reverse to that of rising. The case of setting of
a superior planet in the east never happens. In the case
of setting of a superior planet in the west, if the Iṣṭa-
Kālāṁśas be less than the prescribed Kālāṁśas, ie. y<x,
setting must have already taken place, the Sun having
approached the planet from behind and already effected
heliacal setting. Thus this is also reverse to the condition
of rising as stated. In the case of an inferior planet
setting in the west if y>x, the planet should have set
already since the inferior planet is retrograde while setting
in the west.