AYANA-DRKKARMA That is ayana-dṛkkarma Rversin (M-90°) x Rsin € x Moon's latitude RX R where M denotes the Moon's (sayana) longitude and the Sun's greatest declination. arc MA This formula is also approximate. Referring to the previous figure, we have Rsin LMM'A x Rsin (arc MM') R Rsin LKMP x Rsin (arc MM') R ayana-valana x Moon's latitude R approx. 185 approx. approx. Rversin (M-90°) × Rsin Ex Moon's latitude RX R on substituting the value of the ayana-valana.¹ The formula stated in the text, therefore, is an approximate value of the arc MA, or ML, which is the ayana-drkkarma. When the ayana and latitude of the Moon are of like directions, the longitude of the point L is smaller than the longitude of the point M; and when the ayana and latitude of the Moon are of unlike directions, the longitude of the point L is greater than the longitude of the point M; hence the rule of addition and subtraction stated in the text. ¹ Vide supra, chapter V, stanza 45, p. 171, 2 Vide supra, p. 171 (footnote). The visibility-corrections should be applied as follows. The true longitude of the Moon (which corresponds to the longitude of the point M of the ecliptic) should be first corrected for the 'ayana-dṛkkarma: the resulting longitude corresponds to that of the point L of the ecliptic. This is technically called the polar longitude of the Moon. This polar longitude should then be corrected for the aksa-drkkarma : the longitude thus obtained corresponds to that of the point T of the ecliptic, which rises (or sets) with the Moon's disc. This is technically called the longi- tude of the visible Moon (dṛśya-candra). In the text the order of the corrections is reversed. The difference is negligible.
