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

VIII.18 VIII. ROMAKA-SIDDHĀNTA — SOLAR ECLIPSE 193 अर्धेनाऽऽलिख्य रविं दत्वाऽवनतिं यथादिशं मध्यात् । अवनत्यन्ताच्चन्द्रं विलिखेद् ग्रासार्थमर्धेन ॥ १८ ॥ Eclipse diagram 17. Subtract the parallax-corrected latitude for the time of parallax-corrected new moon, from the sum of semi-diameters. The remainder in minutes are the digits of obscuration of the Sun by the Moon. 18. To represent the amount of obscuration graphically, draw a circle of radius equal to the semi-diameter of the Sun, measure the parallax-corrected latitude north or south according as where the Moon is situated, and with the point marking its end as centre draw a circle of radius equal to the Moon's semi-diameter, to represent the Moon. (The part common to both the circles is the part obscured, and its measure in digits is its width in minutes of arc.) Obscuration in digits = Sum of the semi-diameters, in minutes − parallax-corrected latitude, in minutes. (This for the time of parallax-corrected new moon). The Fig. to illustrate this is given at the end of Example 5, as part thereof. It can be seen from there that the amount of obscuration, AB = SB − SA = SB − (SM − MA) = SB + MA − SM = radius of the Sun + radius of the Moon − corrected latitude = sum of the semidiameters − corrected latitude. The author has taken it that one minute of arc appears to the eye as one digit, though actually the apparent size varies, ('apparent' because this is an illusion), the heavenly bodies appearing to be bigger the nearer they are to the horizon. Example 5. After 59 days has passed from epoch, on the 60th day, there is a solar eclipse. Compute this for Pudukkottai (in S. India) (lat. 10° 23'; longitude 48° east of Yavanapura, represented by 8 nāḍīs of time). The first things to be found are: The Sun and Moon at new moon, the daily motion etc. In Example 1, we have found that the true Sun for 59 days from epoch is rā. 1-28-24. In Example 2, the true Moon is found to be rā. 1-19-36. In Example 3, the Sun's true daily motion for the 60th day is found to be 57', and the Moon's, 835'. In Example 4, the Head of Rāhu is found to be rā. 7-22-41. (All the three longitudes are for mean sunset at Yavanapura, that being the time of day of epoch.) Sun − Moon = rā. 1-28-24 − rā. 1-19-36 = 8° 48'. The Sun being greater, the new moon is to come. The relative daily motion = the difference of the true motions = 835' − 57' = 778'. 18a. B. अद्धनालिख्य रवि 17a. B1.2. ॰दवनिति. A. भवन्ति b. B.1.2. दंत्रा. A.B1.2. नवति c. A.C.D. U. विंद्यात् c. A. यांतश्चंद्रं; B. यातश्चन्द्रं d. A. भानो छन्नानि. A1. चंद्रममसा; A2. चंद्रमदमस्म d. B. विलिखेत्तु ग्रासार्द्धे