vss. 31-33] THE LONGTIUDE CORRECTION 11 The longitude correction and its application: 31. The mean daily motion of the planet multiplied by the longitude (of the place) in terms of ghatls and divided by 60 should be subtracted (from the mean longitude of the planet for mean sunrise at Lanka) (if the place is) to the east of the prime meridian and added (to it) if it is to the west. 1 Sankaranarayana gives the following table for the mean daily motion of the planets : Planet Moon daily motion correct to seconds of arc Mean Sun Moon Moon's apogee Moon's ascending node Mars Sighrocca of Mercury Jupiter Sighrocca of Venus Saturn 59' 8* 13 3 10' 35* 6' 41" 3' 11" 31' 26" 4° 5' 32* 4' 59" 1° 36' 8* 2' Another rule for finding the distance of the local place from the prime meridian : 32. The yojanas (of the distance of the prime meridian)from the local place are obtained on multiplying the longitude in ghatts by the local circumference of the Earth and dividing (the product) by 60. 2 An alternative method for the longitude correction : 33. Whatever is obtained on multiplying the mean daily motion (of the planet) by the yojanas (of the distance from the prime meridian) for that place and dividing by its own (local) earth-circumference is to be subtracted from or added to the mean longitude of the planet (for mean sunrise at Lanka) 1 Gf. MBh, ii. 10(i). 2 Cf. MBh. ii. 10(ii).
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