Chapter on Mean Motion || 1 ||

The planet produced from the count of days, diminished by the constant multiplied by the number of cycles,
and increased by its own epochal position, becomes the mean planet at sunrise.
From the multitude of yojanas A traditional unit of distance, roughly 8-9 miles situated between one's own city and the prime meridian,
minutes of arc measured by one-sixth [of those yojanas] are added or subtracted for the Moon, in the west or east respectively. || 9 ||

Now he explains the correction of the epochal constant for planets derived from the count of days. The planet produced from the count of days: the planet calculated according to the method to be described from the Ahargana The total number of elapsed days since a fixed epoch. Diminished by the constant multiplied by the cycle: subtracted by the constant (Dhruva) which has been multiplied by the number of elapsed 11-year cycles, and then increased by its own epochal position (Kshepaka). Thus, that planet becomes mean at the rising of the maker of day (at sunrise). The intention is that the planet becomes a mean planet at the time of mean sunrise in the city of Lanka The theoretical city on the equator used as the zero-point for Indian astronomical longitudinal calculations. This is stated in the Siddhanta Shiromani A major 12th-century astronomical treatise by Bhaskara II as "The city of the ten-headed one [Lanka]," etc.

To make this applicable to one's own location, he describes a correction: From the multitude of yojanas... From the total distance in yojanas existing between one's own city and the Madhya-rekha (the prime meridian), minutes of arc (minutes) measured by a sixth part (rasa-lava) should be added or subtracted for the Moon, in the west or east respectively. That is to say: if one's city is west of the prime meridian, the value is added; if east, it is subtracted. The measurement of the prime meridian was stated by Bhaskara as "The city of the demons [Lanka]." Here, this correction is made only for the Moon. Because the difference for other planets is very small, it is not performed, and thus there is no error. As stated in the Siddhanta Shiromani: "Because the difference is very small," etc. || 9 ||

Chakra-nighna-dhruvonah = devoid of the constant multiplied by the cycle; Dinagana-bhava-khetah = the planet produced from the count of days; Sva-kshepa-yuk = joined with its own epochal position; Divasakrit-udaye = at sunrise; Madhyamah = the mean planet, it shall be. Indau = for the Moon; Nija-nija-pura-rekhantah-sthitat = from that which lies between the meridian and one's own city; Yojanaughat = from the sum of yojanas; Rasalava-mita-liptah = minutes of arc equal to one-sixth [of the yojanas]; Pare prak = in the west and east of the meridian respectively; Svarnam = addition and subtraction should be performed. The meaning is: in one's own country to the west, addition; in one's own country to the east, subtraction should be done. || 9 ||

Here is the Vasana The underlying logic or demonstration — Observing the difficulty in calculating planets from the beginning of the Kalpa A vast cosmic age, Ganesha The author, Ganesha Daivajna, calculating planets with ease, has derived the desired planets by calculating them in three parts and then summing them. There, the positions of the planets at the start of the text are given as the Kshepaka (epochal positions). Then, the positions for every eleven-year cycle (Chakra) are given as the Dhruva (constant), which are the remainders after subtracting full revolutions (12 signs). Then, the planets produced for the desired days after a cycle are called Dinagana-bhava (produced from the day-count). The sum of these becomes the mean planets at the desired sunrise from the start of the Kalpa. Here, at the start of the text:
Planets = Kshepaka. Planets related to one cycle, purified of revolutions = Dhruva. Mean planet for one cycle = Kshepaka + Dhruva. This for the desired cycle—