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

517 This happens when the star has a long northern latitude and therefore the Ākṣa-Dṛk-Karma correction will be sufficiently large and the star has a small north polar distance. This may be substantiated as follows. Fig. 122 We have the formula cos h = — tan ϕ tan δ which gives the rising hour-angle of the star. When δ is nearly equal to 90—ϕ, then cos h will be nearly equal to ‘—1’ which means that the rising hour angle is nearly equal to 180°, ie. the duration of the star’s stay below the horizon will be very small. This means A' approaches A very nearly (fig. 121), for example when it is in the position A₁'. Then let C₁' be the point which is behind A' by Iṣṭa-nāḍīs so that C₁' the diametrically opposite point C₁ is far ahead of B in stead of preceeding it. This means that the star which should first set heliacally and then after a few days rise heliacally, is now in such a position that it is to rise heliacally even before setting heliacally. This is an un- tenable position. That this is not tenable may be seen otherwise. The diametrically opposite point of Astalagna ie. the point C of the ecliptic which should set along with the planet should have a longitude less than that of the