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

328 OG = Gnomon ; OP = Shadow of the gnomon ; PM = the Bhuja drawn from the extremity of the shadow P perpendicular on the East-west line ; OM = Koti of the shadow extending along the East-west line. AB is the Nalaka placed along the Chayakarṇa PG. The eye is placed at A and the planet ☉ is visible through the tube of the Nalaka AB. Fig. 62 Verses 105, 106 and 107. The method of observing through the instrument called Nalaka, the planetary position. On a horizontal plane mark a point and through it draw the East-west line and also the North-south ; if the planet is in the East mark off the computed Koti of the shadow towards on the East-west line; if the planet is in the Western hemisphere, mark this Koṭi towards the East. From the extremity of the Koti mark the computed Bhuja perpendicular to the East-west line and draw the computed shadow from the point so as to form a right-angled