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

Chapter Ten
SAURA-SIDDHĀNTA — LUNAR ECLIPSE
१०. दशमोऽध्यायः
सौरसिद्धान्तः — चन्द्रग्रहणम्
Introduction
In this chapter the method of computing the lunar eclipse according to the Saura Siddhānta is
given. Since the true Sun and the Moon and Rāhu, the true distances of the Sun and the Moon, and
the Moon’s angular diameter and latitude, have already been given in chap. IX, the angular diameter
of the Shadow alone is given here, as also the computation of the times of contacts etc. The last
three stanzas give the amount of eclipse at a desired time, as also the beginning and end of total
phase of the eclipses, both of the Sun and the Moon.
[तमोबिम्बमानम्]
रविकक्षा नवतिगुणा ‘षडष्टदस्रो’द्धृतेन्दुकक्षायाः ।
छेदः ‘षट्त्रि’घ्नाया ल(ब्धे) नोनश्च षड्वर्गः ॥ १ ॥
‘वियदर्क’गुणे शशिक(क्ष्य)या हृते कार्मुकं त(मो)व्यासः ॥ २ a ॥
Diameter of the Shadow
1-2a. Multiply the Moon’s true distances in its orbit by 36, and divide by the
Sun’s true distance multiplied by 90 and divided by 286. Subtract this result
from 36, multiply by 120, divide by the Moon’s true distance and get the arc
of the resulting sine. This is the angular diameter of the Shadow.
The following is asked to be done:
(i) ‘Result’ = 36 × Moon’s true dist. ÷ (90 × Sun’s true dist. ÷ 286)
= 36 × Moon’s true dist. × 286 ÷ (90 × Sun’s true distance).
(ii) Sine angular diameter of Shadow = (36 − ‘result’) 120 ÷ Moon’s true distance.
Or, simplifying, this is equal to:
{36/Moon’s true distance − (36/Sun’s true distance) × 286/90} × 120
= 4320/Moon’s true distance − 13,728/Sun’s true distance.
1a. A. कक्ष्या. B. नवतीगुणा
b. A. द्रुतेन्दु. A. B 1. 3. कक्ष्यायाः C. षडश्च
c. B 1. 3. षद्रिघ्नाया
d. A. लघोनो; B 1. 3. लधोनातश्च
2a. B 1. 3. वियदर्वगुणे
b. A. B. कक्ष्याया; C. D. कक्ष्या. A. तमोर्व्यांसः;
B 1. 3. तयोव्याघ्रः