Chapter on Eclipses: The Laghumanasa

By reasoning: When two planets are moving in opposite directions (one direct and one retrograde), the sum of their daily motions is used. When they are moving in the same direction (both direct or both retrograde), the difference between their specific motions is used. By dividing the minutes of arc separating the two planets by this [combined or difference] motion, the days [until or since conjunction] are found. The remainder, multiplied by sixty, gives the results in nadis A unit of time equal to 24 minutes; 60 nadis make one day.. This represents the time interval between the desired time and the actual moment of conjunction. Here, the motion must be expressed in minutes of arc. Using these results and the rule of three, one should calculate the planets to be equal at the moment of conjunction.

This is what is being said: At the time of the parvan The new or full moon day, one should calculate the mean positions of the Sun and Moon at midday. Having found those mean positions, one should apply the corrections for terrestrial longitude and the "equation of the center" bhujavivara: the correction for the equation of time due to the eccentricity of the orbit to make them "true" (corrected) positions. These then become the true Sun and Moon. Again, take the difference between them in minutes, multiply by sixty, and divide by the difference of their true daily motions in minutes. The result is the time of conjunction in ghatikas Synonymous with nadis; 24-minute increments and so on. This means the time of the end of the parvan relative to midday.

Furthermore, multiply the true motions of the Sun and Moon separately by those nadis, divide by sixty, and the resulting minutes should be added to or subtracted from the midday Sun and Moon. If the conjunction is yet to come, add them; if the conjunction has already passed, subtract them. At that point, the Sun and Moon become equal. One should set aside these conjunction ghatikas in one place. In the case of a lunar eclipse, however, the nadis are to be calculated from the difference between the Moon and the Sun increased by six signs 180 degrees, representing opposition. In this same way, one should perform the calculation of the time of conjunction and the equalization for other planets as well.

Regarding the bhujavivara correction: multiply one-sixth of the planet's mean daily motion by the minutes of the Sun's "arm-result" The result of the sine of the solar anomaly, and divide by 3610. The resulting minutes should be added to or subtracted from the planet's mean position according to the Sun's position. This is demonstrated by us as follows:

"The minutes of daily motion multiplied by one-sixth of the Sun's arm-result,
divided by 3610, are the minutes to be added or subtracted according to the Sun's arm."

The Teacher Referring to Munjala, the author of the original verses did not explicitly teach this because the difference it makes is not very large. || 2 ||

Now he describes the calculation of the minutes of the diameter of the disks of the Sun and others: "The Sun's..." Divide 7400 by the Sun's true divisor. The result is the Sun's disk in minutes and so on. This means the minutes of the diameter of the solar disk. Dividing 3100 by the Moon's "slow-true" divisor, the result is the Moon's disk. The term "slow-divisor" mandahara is used to specify the divisor used in the second correction process, to exclude the divisor used for the first correction. || 3 ||