पञ्चसिद्धान्तिका (आचार्य वराहमिहिर - सूर्य, रोमक, पौलिश, वासिष्ठ एवं पितामह सिद्धान्त)

X.4 X. SAURA-SIDDHĀNTA — LUNAR ECLIPSE 231 the square root. Multiply this by 120 and divide by the difference of the motions per day of the Sun and the Moon pertaining to the time of eclipse. The duration of the eclipse is got in nāḍikās. 4. Find the Moon’s latitude at first contact and using this find a more correct duration. Repeat this till there is no difference between the previous and the next durations. Note: Though the total duration alone is given here, we are expected to know how to find the first and last contacts from this, from previous contexts. In the successive approximation, what is said for the first contact must be taken for the last contact also. Therefore the following is asked to be done: (i) Rough duration = 120 √(half-sum of angular diameters)² – lat.² ÷ difference of instantane- ous daily motions. (ii) T ± half (i), are the rough first and last contacts. (iii) Using the latitude of the rough first contact and repeating (i) gives successively better first contacts. (iv) Using the latitude of the rough last contact, and repeating (i), gives successively better last contacts. (It should be noted that the shorter the duration the greater are the number of repetitions required.) Example 2. Continue Ex.1. (i) Rough duration in nāḍis 120 √{ (76.9 + 31.77)/2 }² – 23.5² ÷ (780 – 60) = 120 √ 54.34² – 23.5² ÷ 720 = 120 × 49 ÷ 720 = nāḍis 8-10. (ii) Rough times first and last contacts = T – nā. 4-5: T + nā. 4-5. (iii) The Moon at rough first contact = rā. 3-29-6.9, Rāhu then = rā. 3-25-0.2. Moon – Rāhu = 4° 6′.7. From this the Moon’s latitude is 19′.35, north. Using this, a more correct duration for first contact = √54.34² – 19.35² × 120 ÷ 720 = nā. 8-28. Subtracting half this from the time of full moon, the first contact is at T – nā. 4-14. There is no need to repeat, since the duration is long. (iv) The Moon at rough last contact is rā. 4-0-53.1, and Rāhu then, rā. 3-24-59.8. From this the Moon’s lat. is 27′.65, north. Using this, a more correct duration for last contact = √54.34² – 27.65² × 120 ÷ 720 = nā. 7-48. Adding half this to full moon time, the last contact is at T + nā. 3-54. There is no need to repeat. The method has been explained several times before, which need not be repeated here. As for understanding that the successive approximation is for getting the last contact also, though men- 2c. A.B. युतिः. B1.3. हत्या; B3. हत्या 4a. A.B.C. प्रग्रहणेन्दुः 3b. A.B. वियद्वि b. A.B. om. म. A.B. स्थितेः d. A.B. धृते. A.B.C.D. स्थिते for स्थिते; A. लब्धा d. A.B. स्थित्यवशेषः