The mathematical procedure for computing Karakamsha Lagna uses precise planetary longitudes. Here is the step-by-step method:
Step 1: Identify the Atmakaraka (AK)
Convert the longitudes of the seven classical planets (Sun, Moon, Mars, Mercury, Jupiter, Venus, Saturn) to degrees within their respective signs ($0^\circ \text{ to } 30^\circ$). The planet holding the highest degree is designated as the Atmakaraka (the soul significator).
Step 2: Determine the Navamsha division (Pada)
Each zodiac sign spans $30^\circ$ and is divided into 9 equal Navamshas of $3^\circ 20'$ each. By dividing the Atmakaraka's sign degree by $3^\circ 20'$, the calculator identifies which Navamsha division ($1\text{st to } 9\text{th}$) the planet occupies.
Step 3: Map the Navamsha sign according to elemental sign groups
The starting sign for counting Navamshas depends on the element of the birth sign:
- Movable signs (Aries, Cancer, Libra, Capricorn): Counting begins from the sign itself.
- Fixed signs (Taurus, Leo, Scorpio, Aquarius): Counting begins from the 9th sign from the birth sign.
- Dual signs (Gemini, Virgo, Sagittarius, Pisces): Counting begins from the 5th sign from the birth sign.
Counting forward by the Pada index establishes the Atmakaraka's Navamsha sign, which is your Karakamsha Lagna.
Step 4: Compute Lagnamsha (D9 Ascendant)
Applying the exact same 9-fold division rule to your birth Ascendant degree yields the Lagnamsha, which serves as the rising sign of the D9 Navamsha chart.