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

513 y to be in a polar latitudinal conjunction. Hence (y—x) is to be covered by the planet as per its daily motion say m. So the number of days that is to elapse for conjun- ction is (y—x)/m. If x>y, then the conjunction was past by x—y/m. If, the planet be retrograde and x<y, the con- junction was past by (y—x)/m days and if x>y, the planet being retrograde, the conjunction is to take place in (x—y)/m. Note. Though Bhāskara does not mention here Asakṛt-Karma ie. method of successive approximation, it is implied because the motion of the planet differs from moment to moment as well as its Sphutas'ara. Hence having obtained the approximate moment of conjunction, compute again the true motion of the planet at that instant, as well as its Sphutas'ara and Āyana-Dṛk-Karma. The latter ie. Āyana-Dṛk-Karma is to find the polar longitude from the celestial and the Sphutas'ara is the polar latitude ie. SM of fig. 120. The Sphutas'ara is required for the purpose of finding the distance in between the planet and the star on a polar latitudinal circle and not to compute the moment of conjunction. Verses 12, 13, 14. To compute the moments of heliacal rising and heliacal setting of a star. Compute the Udayalagna and the Astalagna of Agastya and Lubdhaka doing Ākṣa-Dṛk-Karma alone. Assuming the Udayalagna to be the Sun, compute the lagna for the Iṣṭa-kāla nāḍīs (ie. after a lapse of Iṣṭanādīs after the moment) given before (namely 2 nāḍīs for Agastya and 2⅙ for Lubdhaka) which will be the longitude of the Sun, when the star (Agastya or Lubdhaka or whatever it be) rises heliacally. Thus the Udayārka is a point of the ecliptic which rises when the star rises heliacally. 65