TIME OF MOONRISE IN THE DARK FORTNIGHT In the night, the time is measured since sunset. 195 Details of the method of successive approximations contemplated in the above rule: 29-31. Determine the time in asus (due to the oblique ascension of the part of the ecliptic) intervening between the rising point of the ecliptic and the (visible) Moon computed for sunset. (This is the first approximation to the required time). Now calculate the positions of the rising point of the ecliptic and the (visible) Moon for that time; and then deter- mine the asus intervening between those positions again. In case the longitude of the (visible) Moon is greater than that of the rising point of the ecliptic, add these asus to the time obtained above; in the contrary case, subtract them. (This is the second approximation to the required time). Repeat this process successively until the successive approximations to the time, the longitude of the rising point of the ecliptic, and the longitude of the (visible) Moon are. (severally) equal (up to vighatis or minutes). At the time ascertained by this proce- dure for the Moon, the Moon is seen (to rise) in the night filling (the space in) all the directions with her rays. The above rule is based on the fact that at moonrise the longitudes of the visible Moon and the rising point of the ecliptic are the same. An alternative rule for finding the time of moonrise in the dark half of the month (III quarter): 32-33. Find out the asus due to the oblique ascension of the part of the ecliptic lying from the setting Sun up to the (visible) Moon; and therefrom subtract the length of the day. (This approximately gives the time of moonrise as measured since sunset). Since the Moon is seen (to rise) at night when so much time, corrected by method of successive approximations, is elapsed, therefore the asus obtained above should be operat- ed upon by the method of successive approximations.
