Western Astrology: Methods, Evidence and Editorial Standards

What each tool supports

The free advanced calculator supports the operations below. The report and Orb columns describe the separate saved natal reading, not the contents of a temporary calculator session.

Calculator results are temporary and never update a saved report. Natal reports include annual profections, daily sampled Jupiter-through-Pluto transits and optional relocation. Sampled peaks are not exact event times. Advanced return, progression, solar-arc, composite and exact-transit results are not added to reports or Orb.

The Wiki also explains methods outside product support, including astrocartography and Davison charts. An educational article is not a working calculator. Availability and errors are shown in the tool; this page is not a live service-status monitor.

Open professional calculator →

Settings that change a comparison

Match these choices before comparing websites. The linked calculation guide gives the full natal conventions and aspect limits.

• Use the same UTC instant and birthplace coordinates. Local-time entry needs a named time zone and an explicit choice when daylight saving repeats an hour; nonexistent clock times must be corrected.
• OpenFate uses the tropical zodiac. Natal defaults are Placidus houses, mean nodes and standard aspect orbs. Seven house systems, true nodes and alternative orb ranges are selectable.
• Advanced settings support 1800–2399. Placidus and Koch are limited to ±65° latitude; other supported houses accept up to ±89°, subject to valid geometry. A different method is never silently substituted.
• Unknown birth time does not establish houses or angles. Planetary progressions and midpoint composites do not supply progressed or composite houses. A solver tolerance is not a measured event-time error.

Inspect the calculation evidence

Choose any input in the fixed synthetic cohort. Each row shows the recorded longitude, an Astronomy Engine reference and their angular difference. The date is the original observation date, not a new run. No customer birth data is used.

September 15, 2026 · A dated check compares 240 planetary longitudes across 24 synthetic inputs with Astronomy Engine, separately from 8 input-rejection checks.

Positions within tolerance

240 / 240

Largest observed difference

0.0045735655°

Predeclared comparison tolerance

0.01°

Expected UTC instants matched

24 / 24

Inputs rejected as expected

8 / 8

Service-reported version: Swiss Ephemeris (@swisseph/node) · 1.2.2. This is the version field returned by the calculation service, not a verified Swiss Ephemeris C-library version. The independent calculation uses Astronomy Engine 2.1.19.

Download the full observation (JSON)

This is a first-party, dated software observation. UTC and input checks are not independent timezone certification. Houses, angles, nodes, retrograde flags, AI interpretations and predictions were not independently validated by this comparison. Repeated birth instants with different input precision are separate inputs, not unique people. It does not establish a competitor winner.

Open the aggregate JSON receipt · Full conventions and calculation checks

Reproduce a difference

1. Choose a case in the evidence viewer and copy its local time, time zone, UTC instant and coordinates. Keep tropical zodiac, Placidus houses and mean nodes for this cohort.
2. Compare unrounded Sun-through-Pluto longitudes against the same reference instant. The comparison tolerance is the protocol tolerance shown with the evidence, not the calculation service’s separate runtime threshold.
3. For houses, nodes, asteroids and timing methods, inspect the separate extended receipt. Its swetest reference shares the Swiss Ephemeris family; this is calculation-chain conformance, not independent implementation certification.
4. If positions agree but an aspect or reading differs, compare orb limits and interpretive choices. Neither geometric agreement nor a synthetic report establishes predictive accuracy or superiority over another product.

Sources and editorial responsibility

OpenFate is responsible for this first-party documentation. AI assists drafting and code review. The records below identify software observations and documentation changes; they do not claim a named astrologer’s review, independent certification or endorsement by a source author.

• Swiss Ephemeris — Swiss Ephemeris documents coordinate, node and house-system conventions. OpenFate’s narrower support settings are stated above.
• IANA Time Zone Database — IANA documents civil-time and daylight-saving history. It is a time-data source, not an endorsement of OpenFate.
• Astronomy Engine — Astronomy Engine supplies the independent longitude reference and the report’s sampled slow-planet transit calculations.

Dated evidence and documentation record

1. September 15, 2026 · OpenFate

   Synthetic longitude observation: fixed inputs compared with Astronomy Engine; download the linked record for the original values, protocol and rejection cases.

2. September 16, 2026 · OpenFate

   Extended conformance observation: house cusps, nodes, optional bodies, civil-time boundaries and selected timing methods checked with the coverage limits in the receipt.

3. September 16, 2026 · OpenFate

   Documentation revision: a dedicated Western methodology hub, explicit calculator/report/Orb boundaries, a full-cohort evidence viewer, source policy and direct correction route. This entry describes documentation work, not a fresh engine benchmark.

Report a correction

Email the page URL or report ID privately, the field in question, both sets of settings, and only the information needed to reproduce the issue. Include the reference and its date. Do not publish another person’s birth data. A verified correction should identify the affected scope and evidence; existing saved reports retain their original records.

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Explore the tools and sources

• Free natal chart
• Open professional calculator
• Complete synthetic report examples
• Astrology Wiki