The aforementioned is true and scientific, when the points are on the ecliptic and with the same amount of right ascension inbetween at the rising or setting of the planet or star and the Sun, as there are degrees (4 min = 1 deg). We shall be obliged to increase or decrease the distances for risings and settings proportionally to the increase or decrease of right ascension.
When the planets or stars are away from the ecliptic by latitude, we shall project them according to the parallels and the so-called paranatellonta, rather than with ecliptic longitude, and then measure the right ascension between the Sun and the computed point, for this indicates the true rising and setting of the stars. If one is willing to take an additional trouble, he might as well take the exact current magnitude of the star and modify the mean arcus visionis accordingly. For though most powers come from the ecliptic and its division into twelve places, the rays of the planets increase or decrease in power with respect to the rays of the Sun, which naturally move in absolutely all directions unlike the four aspects. Truthfully, the King said ''the whole circle has been entrusted to the Sun's care''.
Sources:
Fatoohi, L. J., Stephenson, F. R., & Al-Dargazelli, S. (1998). The Danjon limit of first visibility of the lunar crescent. The Observatory, 118, 65-72.
Schoch, C. (1924). The “arcus visionis” of the planets in the Babylonian observations. Monthly Notices of the Royal Astronomical Society, 84(9), 731-735.
