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Calculation Methodology

Our commitment to astronomical precision, open standards, and total user privacy.

Astronomical Standards

FindMyRisingSign.com computes the Ascendant using the Swiss Ephemeris (Moshier algorithm compiled to WebAssembly via @swisseph/browser). The Swiss Ephemeris is the gold standard astronomical library created by Astrodienst AG, used worldwide by professional software for calculating planetary positions and house cusps.

Core Pipeline

  1. Geographic Coordinates: City search resolves exact latitude and longitude decimal degrees via Open-Meteo Geocoding API.
  2. Timezone & DST Resolution: Convert local birth time to UTC using the IANA Time Zone Database via the browser's native Intl.DateTimeFormat engine. This guarantees historical Daylight Saving Time accuracy.
  3. Julian Day Conversion: The UTC timestamp is converted into a standard Julian Day number.
  4. House System: We compute house cusps using the Placidus house system ('P'), which is the standard house division system in Western astrology.
  5. Zodiac Mapping: The resulting ecliptic longitude (0°–360°) is mapped to the 12 tropical zodiac signs (0° Aries = Vernal Equinox).

Browser-Side Execution & Privacy

Unlike legacy calculators that send sensitive birth date and time inputs to a remote server, our calculator executes 100% locally within your browser using WebAssembly. Your birth date, birth time, and birth location data never leave your device.

Want More Technical Details?

Read our step-by-step technical guide explaining every phase of the calculation algorithm.

Read How Our Calculator Works →

Open Source & Licensing Attribution

The Swiss Ephemeris is developed by Astrodienst AG (Zurich, Switzerland) and licensed under the GNU Affero General Public License (AGPL-3.0). Geocoding data is powered by Open-Meteo and GeoNames under open licenses.