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

477
First half of verse 8. To obtain what are called
Iṣṭa-Kālāṁśas.
The time between the rising of the planet or of the
Dṛk-graha and that of the Sun measured in ghaṭīs multi-
plied by six gives what are called Iṣṭa-Kālāṁśas.
Comm. Having found the approximate position of
the Dṛk-graha as mentioned above when the planet is
likely to rise or set heliacally, let the time in between the
rising of this Dṛk-graha and that of the Sun (if it be the
case of setting or rising in the west the position of the
Sun is to be increased by 180° because the astalagna
directed to be found in verse (1) is the point of intersection
of the ecliptic with the eastern horizon, which is removed
180° from the setting point of the Sun) be multiplied by
six. Since both the Dṛk-graha and the Sun's position are
points on the Ecliptic and since we have considered the
time in between their rising moments, which is measured
on the equator, and again since this time is measured in
ghaṭīs, the number of ghaṭīs multiplied by six give the
degrees, for, each ghaṭī corresponds to six degrees of the
equator (sixty ghaṭīs corresponding to one sidereal day).
These degrees are said to be Iṣṭa-Kālāṁśas, which means
that it gives the arc in between the feet of the declination
circles of the Dṛk-graha and the Sun at the Iṣṭa-kāla ie.
that particular time considered.
Second half of verse 8 and verses (9) and (10).
If the number of degrees so found ie. the Iṣṭa-
Kālāṁśas fall short of or exceed the number of Kālāṁśas
postulated for the rising or setting of the planet, then the
planet's rising has to take place or has already taken place
respectively and vice versa in the case of setting. The
number of minutes of the difference of the prescribed and
Iṣṭa-Kālāṁśas multiplied by 1800 and divided by the
rising time of the Rāśi expressed in Kalās and again