How a Ṣaṣṭyāṃśa D60 Chart Is Calculated

Two explicit sign conventions

Bṛhat Parāśara Horā Śāstra 6.33 tells the reader to omit whole signs, double the within-sign longitude, divide by twelve, and add one to the remainder. A literal zodiacal reading starts the D60 sign count at Aries. P. V. R. Narasimha Rao’s Vedic Astrology: An Integrated Approach, §6.2.20 instead says to count the sixty signs from the occupied D1 rāśi itself. Our calculator offers both with distinct labels and defaults to Rao’s documented worked convention.

Take the zero-based D1 sign index and the degree within it. The zero-based portion is floor(within-sign degree ÷ 0.5°). For Rao, D60 sign index = (D1 sign index + portion) modulo twelve. For the Aries reading, D60 sign index = portion modulo twelve. At an exact 0°30′ boundary, begin the new portion. At exactly 30° in a rāśi, start portion one of the next D1 rāśi.

Rao’s example is Jupiter at 222°58′, or 12°58′ Scorpio: portion 26. It becomes Sagittarius under Rao’s occupied-rāśi rule and Taurus under the Aries-start reading. This visible difference is why the form does not quietly blend the two methods.

Sixty traditional names

Parāśara 6.34–39 supplies the name sequence for odd D1 signs; 6.40 reverses it for even D1 signs. The table gives both name directions and the Aries-start D60 sign. For Rao’s sign, start from the D1 rāśi instead. Repeated names such as Deva, Ghora, Kala, Amrita, Komala, and Saumya are intentional; transliteration and a few compounds vary by edition. These are traditional labels, not additional astronomical bodies or measured predictions.

Time, nodes, and scope

A half-degree Lagna portion can change within minutes. Its rate varies with latitude, date, and rising sign; there is no universal two-minute promise. The form recomputes the actual D1 Lagna at ±1 and ±5 minutes, and its position table shows distance to the nearest edge. A rounded birth time, wrong historical UTC offset, changed ayanamsha, or different ephemeris can shift an assignment.

This site uses Astronomy Engine 2.1.19 and an approximate Lahiri ayanamsha for D1; it is not Swiss Ephemeris. Its lunar nodes are mean nodes, with Ketu opposite Rahu in D1. Under Rao’s rāśi-start rule, their D60 signs are also opposite; under the Aries-start reading, opposite D1 points with the same within-sign degree map to the same D60 sign. The manual longitude lookup works when a planet’s sidereal longitude is known, but a time-unknown D60 Lagna is withheld. Parāśara 7.6 gives D60 a broad remit. Claims that D60 alone reveals a past life are a later interpretive emphasis, not the wording of that verse. Treat chart interpretation as a cultural practice rather than a verified outcome.