Proof:-- + Moon's longitude at sunrise-Sun's longitude at sunrise MEAN LONGITUDE BY ORBITAL METHOD avamasesa ponding to lunar days in a kalpa = tithi at the beginning of the current tithi Moon's daily motion in degrees -Sun's daily motion in degrees 12 12 = tithi at sunrise = tithi at the beginning of the current tithi + tithi corres- = because tithi corresponding to 1 civil day Moon's daily motion in degrees X From stanza 8 above, we have mean longitude of a planet But from vii. 20 avamašesa lunar days in a kalpa Another rule for finding the mean longitude of a planet : 20. Divide the (yojanas of the circumference of the sky by the number of civil days (in a yuga): the result is the number of yojanas traversed (by a planet) per day. By those (yojanas) multiply the ahargana and then divide (the product) by the length (in yojanas) of the own orbit of the planet. From that are obtained the revolutions, signs, etc. (of the mean longitude of the planet). length of a planet's orbit, (revolution-number of the planet) x ( ahargana). civil days in a yuga 13 Sun's daily motion in degrees 12° circumference of the sky¹ revolution-number of the planet ¹ For the length of the circumference of the sky, see vii, 20,
