Four quarters, four angular signs
Chaturthamsha, also written Caturthāṁśa or Turyamsha, is the fourfold divisional chart D4. A sidereal rāśi spans 30°. Divide it into four equal 7°30′ intervals. The first quarter maps to the original sign, the second to its fourth sign, the third to its seventh, and the fourth to its tenth. Count signs forward, including the original as number one. The sequence therefore follows the four kendras from each D1 sign.
Bṛhat Parāśara Horā Śāstra, chapter 6, verse 9 names the lords of the original sign and its angles as the lords of the four parts. The Parāśara Jyotiṣa Course D4 table spells out each quarter and works a 13°21′ Taurus example, which lands in Leo. We use that published example as an arithmetic check, not as a prediction.
The calculator derives D4 from this site's sidereal D1 positions. It uses Astronomy Engine 2.1.19, an approximate Lahiri ayanamsha, seven classical grahas, and mean Rahu and Ketu. D4 Lagna additionally needs a recorded time, location, and historical UTC offset; the site does not infer time-zone history from a place name.
What the result includes
The result retains each graha's original sidereal D1 position beside its numbered quarter and D4 sign. A South Indian fixed-sign diagram places the derived grahas and Lagna. The displayed degree within a D4 sign is a mathematical expansion of its 7°30′ interval, not a second observed longitude.
In Jyotish literature D4 is associated with bhāgya, or fortune; modern practitioners often examine home, land, and property. The result does not establish a future purchase, inheritance, or financial outcome. Review the D4 calculation guide and the underlying D1 rāśi chart together.