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

ॐ THE TRIPRAŚNĀDHIKĀRA Verse 1. The purport of this chapter. Pandits say that this is the science of time in as much as, herein there is described the method of knowing the direction and the point of space (where a celestial body is situated) given the time. Hence I expound that chapter, which gives that knowledge and which abounds in very important statements, which forms the quintessence of the science of astronomy. Comm. This chapter is called Tripraśnādhikāra, since this deals with the three questions pertaining to the direction and the point of space of a celestial body for a given time ie. dealing with Deśa, Dik and Kāla. In this chapter we come across the Hindu methods of spherical trigonometry, and gnomonics or Śaṅkuvedha or observations with the help of a gnomon. Also we find herein a usage of what is called ‘Golayantra’ or the armillary sphere, which helped the Hindu astronomers to solve all diurnal problems. We find herein Bhāskara excelling himself. This chapter abounds in a good number of technical terms and without a knowledge of this chapter, no one could call himself a Hindu astronomer. Verses 2-4. To compute what is called lagna given the time. The lagna or the ascendant as it is called or the point of intersection of the ecliptic with the horizon at a given point of time is obtained as follows. Obtain the Sāyana longitude of the Sun at the point of time at which it is required to find the lagna. Supposing the Sun is in the rth degree of a particular Rāśi, the number of asus which