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

148 PAÑCASIDDHĀNTIKĀ V. 10
कृत्वैवं क्षयवृद्धी व्य(र्काच्चन्द्राद् वि)शोध्य चक्रा(र्धम्) |
शेषोदयकालसमे शशिदिवसा(न्ते) शशी मध्ये || १० ||
10. In the manner given (in verse 8), correct the Moon for moonset, deduct
the Sun from this corrected Moon, and deduct 6 rāśis from the remainder.
Find the time by which the remaining segment will rise, after sunrise. This is
the time from sunrise when the Moon will set. At the time exactly midway bet-
ween moonrise and moonset, the Moon will reach the meridian, (i.e. will be at
upper culmination).
The following is the work to be done:
i. The correction (for latitude) = the Moon's latitude × the equinoctial shadow ÷ 12 (This is
known as Akṣadṛkkarma).
ii. This correction is to be applied to the true Moon. Corrected Moon = True Moon ± Correction.
(If the time of moonrise is to be found, then the correction is subtractive if the Moon's latitude is
north, and additive if it is south. If moonset is wanted, if the Moon's latitude is south, the correction
is subtractive, if north it is additive).
iii. The time of moonrise is found thus: The corrected Moon - True Sun = elongation. The time
of rise of the segment of elongation from sunrise is the time of moonrise. (In other words, the
corrected Moon's position on the ecliptic being known, the time when that point rises is the time
of moonrise). When the elongation is less than 6 rāśis, moonrise is in the day-time, otherwise at
night.
iv. The time of moonset is found thus: Corrected Moon - Sun = elongation. The time of rise
of (the segment of elongation - 6 rāśis) from sunrise, is the time of moonset. (In other words, the
time of rising of the point diametrically opposite to corrected Moon is the time of moonset). Here,
if the elongation is less than 6 rāśis, then the moonset is in the night, and if greater, it is in the day-
time.
v. Moonrise to moonset is the moon-day-time. It is obvious that at the middle of its day time it
is on the meridian.
It is obvious that the times of rising and setting will be correct if the longitudes and Moon's
latitude of those times are used. But as the computation as done here is only approximate, we can
guess the approximate times of moonrise and moonset for the day from the tithi of the day, and use
the elements of those times, to get tolerably accurate times.
Example 4. The equinoctial shadow for a certain place (in the northern hemisphere) is 4 aṅgulas. The ascen-
sional differences for the place are for Aries 236 vināḍīs, Taurus 265, Gemini 309, Cancer 337, Leo 333,
10a. A.क्रत्वैवं; B. तच्चैवं. A.B. वृद्धि
b. A.B.C.D. U. व्यर्कै; (B2. व्यर्क) चन्द्रं विशोध्य d. B3. पशि and C.D. निशि for शशि
चक्रार्धात् A.B.U. दिवसाद्धे;. D. दिवसेऽस्तं
c. A. शेखोदय; B. मेषोदय A.B. शशिमध्ये; C. शशी याति