Methodology & Calculation Limits

Calculation first, interpretation second

The tools separate astronomical positions, mathematical or traditional rules, and editorial interpretation. Astronomy can locate celestial bodies; it does not establish the truth of personal predictions. Interpretive text is offered for cultural interest and reflection.

Ephemeris, zodiac and houses

A local copy of Don Cross’s MIT-licensed Astronomy Engine calculates apparent geocentric ecliptic positions. No birth details are sent to an external ephemeris API. Chart longitudes are converted to a sidereal zodiac with an approximate mean Lahiri ayanamsa: a J2000 anchor of 23.85305556° plus a documented general-precession polynomial. This is not Swiss Ephemeris and is not a claim to reproduce its true Lahiri implementation exactly.

Lagna uses local apparent sidereal time, latitude and obliquity. Whole-sign houses start with the rising sign. Rahu and Ketu use a mean lunar-node formula and are kept 180° apart. True-node implementations can differ. We do not calculate divisional charts, Shadbala or every classical Yoga in this version.

Time, location and supported range

Birth forms support 1900–2100 and latitudes within ±66°. Indian cities come from a bundled coordinate list; other locations can be entered manually. IANA time zones use the browser’s historical time-zone data, while the fixed UTC+05:30 option deliberately uses a constant offset. A repeated daylight-saving clock hour can be ambiguous: verify the offset for that birth. Invalid skipped clock times are rejected.

Unknown birth time uses a clearly labelled noon estimate. Lagna and houses are omitted. The Moon-sign tool also compares the start and end of the local day. A boundary-crossing unknown-time input must not be presented as an exact matching score. Near sign, Nakshatra or Pada boundaries, improve the input and compare an independent ephemeris.

Accuracy and the corrected reference case

The project’s validation targets are about 0.02° for the Sun and 1° for the Moon and planets. These are acceptance targets, not a universal guarantee over every supported date. Ayanamsa approximation and birth-time uncertainty are separate sources of error. We show degrees and minutes without suggesting that every displayed digit has independent validation.

For the supplied reference input, 17 September 1950, 11:00 IST, Vadnagar, the calculation gives Scorpio Lagna, a sidereal Moon near 218.8°, and Anuradha Pada 2. The initial brief’s Vishakha-4 label for the Moon was inconsistent; Vishakha-4 describes the early-Scorpio ascendant in a commonly published chart, not that Moon. Public birth data for this person are themselves disputed, so this is a fixed numerical test input, not a claim that the birth time is proven.

Ashtakoot matching and exception rules

Eight factors total 36 points: Varna 1, Vashya 2, Tara 3, Yoni 4, Graha Maitri 5, Gana 6, Bhakoot 7 and Nadi 8. Directional tables treat chart A as the traditional groom position and B as the bride position. Varna is historical terminology inside this table, not a judgment of caste, worth or eligibility. Regional matching systems differ.

Before displaying a result, this implementation checks two selected Nadi exceptions: the same Moon sign with different Nakshatras, or the same Nakshatra across different signs. It also checks a Bhakoot exception when the sign lords are the same or mutual natural friends. Supported exceptions restore the relevant points, while the raw total stays visible. Other schools may not make the same adjustment.

A separate Manglik screen checks Mars in houses 1, 2, 4, 7, 8 and 12 from Lagna when birth times are known. Both charts meeting that screen is reported as a possible balancing consideration; it does not change the eight-koota total. This is not an exhaustive Dosha analysis. No score measures relationship safety, consent, health or fertility.

Vimshottari and Panchang

Vimshottari follows Ketu 7, Venus 20, Sun 6, Moon 10, Mars 7, Rahu 18, Jupiter 16, Saturn 19 and Mercury 17 years. The birth Nakshatra chooses the first lord and the unelapsed fraction gives the balance. Antardashas are proportional. We use 365.2425 days per year; a 360-day convention produces different calendar dates.

Panchang factors are evaluated at local sunrise: Tithi from 12° Moon–Sun intervals, Nakshatra from 27 sidereal Moon sectors, Yoga from the sidereal Sun-plus-Moon sum, Karana from half-Tithis, and Vara from the sunrise-based weekday. Sunrise and sunset use Astronomy Engine’s horizon search. A whole daily label does not remain valid at every later clock time.

Editorial readings and other traditions

Rashifal combines a chosen Moon sign with calculated Panchang factors at noon in India using a fixed editorial rule set. It is general sign-level reflection. Tarot uses 22 Major Arcana with a deterministic name-and-India-date shuffle. Numerology labels date reduction, Chaldean name arithmetic and Lo Shu separately. The number Yantra is a mathematical date square, not a consecrated Sri Yantra.

Sources and corrections

Want to check where the method comes from? These references let you inspect the calculation software, compare a test example and read about the tradition. Each link opens an external website in a new tab.

The journal records its publication metadata and the date of the current revision. A correction can be sent through Instagram with the affected page and a reproducible example. Do not post private birth details publicly.