Methods
The sky
Planet positions come from NASA's Jet Propulsion Laboratory ephemeris (DE440s), read through the Skyfield astronomy library: geocentric apparent positions for the exact moment of birth, converted from your local time and place using the historical time-zone and daylight-saving rules for that date. Positions agree with independent astronomy libraries to within arcminutes. The lunar node is the mean node.
Western astrology
Tropical zodiac. Placidus houses, computed to satisfy the Placidus definition exactly (not interpolated from tables). Aspects within standard orbs, with patterns (grand trines, T-squares, stellia, angular planets) detected from them.
Vedic astrology
Sidereal zodiac with the Lahiri ayanamsa (IAE). Whole-sign houses from the Lagna. Nakshatras and padas from the Moon's sidereal longitude. Vimshottari dashas with 365.25-day years, including sub-periods. Navamsa (D9). Pancha Mahapurusha yogas, Gajakesari, Budhaditya, Chandra-Mangala, neecha bhanga and Kemadruma with its cancellations, each tested from the actual placements. The Jaimini atmakaraka is the planet with the highest degree.
Progressions
Secondary progressions, one day for each year of life (tropical year), with the Midheaven moved by solar arc. The progressed Sun's sign marks a chapter of roughly thirty years; the progressed Moon's sign a season of about two and a half years. The progressed lunation phase is reported too.
Timing cycles
Annual profections counted from the Ascendant sign, one house per year of life, with the lord of the year. Returns and hard aspects of Jupiter, Saturn, Uranus, Neptune and Pluto to their own birth positions, with exact dates found by root-finding on the ephemeris, not estimated. Current transits to natal points within two degrees. The forecast scores every day across all six systems against your own two-year baseline, so "high" means unusual for you, and flags the dates when independent systems point at the same thing.
BaZi
Four Pillars from the solar terms, with the month pillar changing at the exact solar-term moment computed from the ephemeris. Local apparent solar time for the hour pillar; the day turns at 23:00. Luck pillars from the year stem's polarity and sex at birth, which is why we ask for it (optional). Day Master strength from the season and the supporting elements. The pillars match an independent Chinese-calendar library in verification runs.
Numerology
Pythagorean. Life Path from the full birth date; Expression, Soul Urge and Personality from the full birth name, reduced word by word, keeping the master numbers 11, 22 and 33. Personal year, month and day from the birth month and day with the current date.
Places and time zones
Birth places are looked up on our own server from the GeoNames gazetteer (about 237,000 places with population over 500, each with its time zone), so the place you type is never sent to anyone else. Historical time zones and daylight-saving rules come from the IANA time-zone database.
The writing
Readings are written from these calculations by a language model under a fixed standard: use only what was calculated, cite the calculation behind each sentence, name the system behind every sign, state agreements and disagreements between systems, never predict events, and give the member's own words priority over the chart. Every written reading shows its sources; every number is in the calculations appendix of your chart.