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