142 TRUB LONGITUDE OF A PLANET To the longitude of the mandocca ("apogee"), apply (the spasta-bhuja due to the mandakendra, as a positive correction) in the manner prescribed above (in stanza 22). From the longitude of the sighrocca subtract the spasta-bhuja (due to the sighra- kendra) (as follows) : (When the sighrakendra is) in the first and second quad- rants, subtract from the longitude of the sighrocca the spasta- bhuja itself and that subtracted from half a circle (i.e., 180°) respectively; (when the sighrakendra is) in the remaining quad- rants (i.e., third and fourth), subtract that (spasta-bhuja) as increased by half a circle and that (spasta-bhuja) subtracted from a circle respectively. In Fig. 16, let the circle UMN centred at E, the Earth, be the con- cyclic (kakṣāvṛtta), the circle centred at. C the manda eccentric (manda- prativṛtta), U the planet's mandocca (apogee), and M the mean position of the planet. Let MM, be parallel to EU; and let S be the point where CM, intersects the concyclic, and T' the point where MM, and ES produced meet. Then T is the position of the true-mean planet and S the position of the true-mean planet on the concyclic. If be the first point of Aries, then are US is the true- mean longitude of the planet. When the mean planet is in the first quadrant begin- ning with U, as shown in the figure, arc TUS-TU+US, i. e., true-mean longitude = longitude of the planet's apogee + spasta-bhuja.¹ M U When the mean planet is in the second anomalistic quadrant, the spasta-bhuja is the arcual distance of the true mean planet from the perigee M. Thus, in this case N Fig. 16 ¹ As in the case of the Sun, arc MU is the bahu or bhuja (due planet's mandakendra) and arc SU is the spaṣṭa-bhuja.
