Neelakantha's Persian Astrology

The remaining three houses and their junctions (sandhis) The 'sandhi' is the transition point or cusp between two astrological houses are to be calculated as follows: by subtracting the previously determined sixth-part value and adding it to the fourth house, the junction between the fourth and fifth houses is found. Adding it again gives the fifth house itself. Adding it once more gives the junction between the fifth and sixth houses. Adding it again gives the sixth house. Finally, adding it again gives the junction between the sixth and seventh houses. Thus, the six houses with their junctions are produced. By adding six signs (180 degrees) to these, the remaining six houses and their junctions are determined. Now, the purpose of establishing these house junctions is explained: "The Planet..." When a planet is situated in a house and its position in signs, degrees, and minutes exactly matches the center of that house, it gives its full result—whether good or bad—rated at twenty units original: "vimsati-vimbam," a traditional scale of 20 points for planetary strength. If the planet is exactly at the junction (sandhi), its result is zero.

The next three houses are likewise calculated; by adding six signs, the other six are found.
When a planet equals the house center, its fruit is full; at the junction, it is nil. || 26 ||

From the desired time of birth, one should calculate the difference between the rising times of the signs. If the sun is subtracted or added, that becomes the ascendant (lagna) The sign rising on the eastern horizon at the time of birth. For a birth at night, the ascendant is calculated by adding six signs to the sun's position. || 27 ||

Now, if the elapsed portion (bhukta) or the remaining portion (bhogya) of the Sun—calculated according to the rules—cannot be subtracted from the hours and minutes of the desired time, then by what means should the ascendant be calculated? To this, he says: "The elapsed..." If the elapsed or remaining portion cannot be subtracted from the desired time's hours and minutes, then those hours and minutes should be multiplied by thirty and divided by the rising time of the tropical Sun Sayana-surya: the sun's position adjusted for the precession of the equinoxes. The resulting degrees and minutes should be subtracted from or added to the Sun. Specifically, if the "elapsed" portion was used, the result is subtracted from the Sun; if the "remaining" portion was used, the result is added to the Sun. That becomes the ascendant. For calculating the ascendant at night, the calculation is performed using the Sun's position plus six signs. Even for calculating the tenth house (midheaven) at night, it is derived from the Sun plus six signs.