Nilakantha's Annual Horoscopy

...should be performed. The junction Sandhi: the boundary point between two astrological houses between the Ascendant and the second house is where the influence of the Ascendant ends and the second house Dhana-bhava: the 'House of Wealth' or second house begins; this should be understood by all. By adding the previously calculated sixth part original: "shashtamsha"; the distance between house centers is divided by six to determine boundaries, the first junction is reached. By adding that same sixth part again, the second house center is found. Adding it once more gives the junction between the second and third houses. Adding it again gives the third house center. Adding it again gives the junction between the third and fourth houses.

In this manner, the first three houses and their junctions are established. Following this, the next three houses and their junctions must be calculated. Specifically: subtract the value of the sixth part from the center. By applying this to the fourth house Sukha-bhava: the 'House of Happiness' or fourth house, the junction between the fourth and fifth houses is found. Adding it again gives the fifth house center. Adding it again gives the junction between the fifth and sixth houses. This results in the sixth house center. Adding it again gives the junction between the sixth and seventh houses. Thus, the first six houses and their junctions are produced. By adding six signs 180 degrees to these, the remaining six houses and their junctions are determined. Next, the author explains the purpose of calculating these house junctions:

By adding the sixth part to the Ascendant, the junction is found; by further additions of the sixth part,
the three subsequent houses with their junctions are determined. By adding or subtracting the sixth part from the Fourth House, the rest are found. ॥ 26 ॥
If the traversed or remaining portion of the Sun's sign cannot be cleared from the desired time, multiply the time by thirty (30)
and divide by the local rising time to find the degrees and minutes. Add or subtract this from the Sun to find the Ascendant; at night, add six signs to the Sun's calculation. ॥ 27 ॥

Whichever house a planet resides in, if its position in signs, degrees, and minutes is exactly equal to the center of that house, then that planet gives its full result—whether auspicious or inauspicious—at a strength of twenty units Vimshati-vishvatmaka: a traditional scale where 20/20 represents 100% effectiveness. However, if a planet is positioned exactly at the junction Sandhi between two houses, its result becomes zero. ॥ 20-26 ॥

Now, if the traversed portion bhukta or remaining portion bhogya of the Sun (calculated by the previously mentioned method) cannot be "cleared" subtracted from the desired time Ishta-kala: the time elapsed since sunrise in ghatikas and palas, how should the Ascendant be calculated? To answer this, the text says: If the traversed or remaining portion...

If the rising time of the Sun's portion cannot be subtracted from the desired time, then the units of desired time (ghatikas and palas) should be multiplied by thirty and divided by the local rising time svodaya of the sign the Sun is currently in. The resulting degrees and minutes should be noted. These are then added or subtracted from the Sun’s position. Specifically, if you are working with the "traversed" portion, subtract the result from the Sun. If you are working with the "remaining" portion, add the result to the Sun. The resulting position is the Ascendant Lagna.