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

Chapter Nine SAURA-SIDDHĀNTA — SOLAR ECLIPSE ९. नवमोऽध्यायः सौरसिद्धान्तः — रविग्रहणम् Introductory In the first portion of this chapter the Sun, Moon and Rāhu according to the Saura Siddhānta are given, and in the latter portion, the computation of the solar eclipse according to the same. In agreement with the author’s statement in his Introduction to the PS, that the tithi got by the Saura is very accurate, we see that not only the tithi but most other constants as well are wonderfully accu- rate, and approximate closely to the modern values. Among the five Siddhāntas this is the only one that uses epicycles to compute the Equation of the centre of the Sun and the Moon, and later in chapter XVII, the Equation of the centre and equation of conjunction of the ‘star-planets’, followed later by astronomers like Āryabhaṭa. The Ārdharātrika-pakṣa of Āryabhaṭa, expounded by Brahmagupta in his Khaṇḍakhādyaka, follows this Saura-Siddhānta in its constants. Though the computation of Days from Epoch (‘days’) has not been specially given for the Saura, (the rule given in I.13 not being clear whether it is related to the Saura or not), yet from the Yuga-elements of the Saura in I.14, it is possible to formulate rules for ‘Days from Epoch’, following the Saura, as has been shown by us in our Notes under I.14. We have also explained how the ‘days from Epoch’ obtained from the Romaka or Pauliśa rules can be used for the Saura also, provided we bear in mind the variation in time of commencement of the Epoch, as for instance, that the epoch for the mean Sun and Moon, their apogees, and the Moon’s node is for mid-day at Ujjain, and for the star-planets it is mid-night. Now, the author, intending to deal with eclipses, gives first the Sun, Moon and Rāhu on which eclipses depend, beginning with the mean Sun. [रविमध्यम्] द्युगुणोऽर्कोऽष्टशतघ्ने विपक्ष‘वेदार्णवे’ऽर्कसिद्धान्ते । ‘स्वरखाऽश्विद्विनवयमो’द्धृते क्रमाद्दिनदलेऽवन्त्याम् ॥ १ ॥ Mean Sun

1. According to the Saura-Siddhānta, to get the mean Sun in revolutions etc., multiply the days from Epoch by 800, deduct 442, and divide by 2,92,207. This is for Ujjain mean noon.
2. Paraphrased by Utpala or BS 2, p.65. 1a. A.B1. णेर्केष्ट. A2. शतघ्नो c. A.B1.2. ॰खाद्विधिनव०; C. ॰खाद्विद्विनव० d. A. हृते; B1.2. धृते. A2. दिनं. A1. ॰वत्यां; B. ॰वत्या