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

270 Shadow on Dec. 23 No Shadow in this direction on Dec 23 Immediately before 21st March B C A On 21st March Immediately after 21st March No Shadow in this direction on 22nd June W B C A E JUNE when δ=φ On 22nd JUNE Fig. 48A Showing the locus of the extremity of the shadow on different days at a latitude of 17° Note. OA, OB are the shadows computed by Bhāskara when the Sun is on the prime-vertical. In the method of finding the shadow under verse 46, we perceive Bhāskara's genius in (1) looking upon the shadow as being made up of two segments namely that due to φ and that due to the declination (2) in conceiving what he calls Iṣṭa-drik-mandala palabhā, and Iṣṭa-drik- mandala Krānti and (3) in deriving the equation H sin D = (H sin ZT × H sin δ) / (H sin φ) Latter half of verse 47 and verse 48. Something to be noted. In computing the shadow in a given direction, there may be two shadows at times in the northern hemi- sphere. When H sin a < Agrā and there will be none in the southern. To compute the second shadow we have to take 180 − L also as the latitude where L is the latitude computed, and proceed in the same way as we have done before.