Twelve parts of a sidereal sign
Dwadashamsha (D12) divides each 30° rāśi into twelve equal parts of 2°30′. The first part maps to the natal sign itself; each next part moves one sign forward. This pattern is the same for odd and even signs. At exactly 2°30′, 5°, 7°30′, and each later boundary, a new part begins.
For example, 11° Gemini falls in part five and maps to Libra. A point at 19° Scorpio falls in part eight and maps to Gemini. These examples follow P. V. R. Narasimha Rao's worked D12 method. The displayed D12 degree stretches a 2°30′ interval across 30°; it is a derived coordinate, not a second planetary observation.
The tool computes sidereal D1 positions with Astronomy Engine 2.1.19 and an approximate Lahiri ayanamsha before applying the D12 rule. It includes seven classical grahas and mean Rahu and Ketu. Its D12 Lagna comes from the transformed D1 ascendant and needs a recorded time, place, and historical UTC offset.
Read D1 beside D12
The result keeps every D1 sign and degree beside its derived D12 position, its numbered 2°30′ part, and the division name recorded in the source verse. The South Indian diagram fixes signs in place and marks the transformed Lagna. The labels Ganesha, Ashvini Kumaras, Yama, and Sarpa repeat three times in every natal sign; the page does not turn them into predictions.
For a hand calculation and source notes, read the Dwadashamsha method guide. Start with the D1 rāśi chart to check the underlying sidereal positions.