Compute Natal Chart
astral_compute_natal_chartCompute a natal birth chart with planet positions, houses, aspects, and chart signature from birth data. Includes precision audit for accuracy.
Instructions
Compute a full natal (birth) chart from birth data: planet signs/degrees/houses, retrogrades, major aspects with orb and strength, the Ascendant/MC, and a derived signature (dominant element/modality, chart pattern, stelliums, angular planets). By default the chart is precision-audited by a second independent ephemeris. This is the primary tool. If you only have a city name, call astral_search_birthplace first to get latitude/longitude/timezone. Use privacy_mode to control payload size (a full chart is large): 'full' (default) returns everything; 'structured' drops redundant fields; 'summary' returns only the luminaries, Ascendant, chart signature and top aspects to save tokens.
Input Schema
| Name | Required | Description | Default |
|---|---|---|---|
| zodiac | No | Zodiac. 'tropical' (Western, season-anchored) or 'sidereal' (Vedic/constellation-anchored). | tropical |
| latitude | Yes | Birth latitude in decimal degrees, -90..90. Resolve from a city name with astral_search_birthplace if you don't have it. | |
| timezone | Yes | IANA timezone of the BIRTHPLACE at birth, e.g. America/Fortaleza. Not the caller's timezone. astral_search_birthplace returns this for each match. | |
| longitude | Yes | Birth longitude in decimal degrees, -180..180 (negative = West). Resolve with astral_search_birthplace if unknown. | |
| birth_date | Yes | Birth date as YYYY-MM-DD, e.g. 1989-02-23. Years before 1900 and after 2100 are supported but less precise. | |
| birth_time | No | Local birth time as 24h HH:MM, e.g. 14:30. Optional — if unknown, noon is assumed and house/ascendant accuracy drops (planets stay accurate). | |
| house_system | No | House system. 'placidus' is the modern default; 'whole-sign' is common in traditional/Hellenistic work; others: koch, campanus, regiomontanus, topocentric, equal-house. | placidus |
| privacy_mode | No | Payload verbosity — how much of the chart to return, independent of response_format (which only picks markdown vs json). 'full' (default) returns the complete payload: every planet, house and aspect plus the per-planet precision audit. 'structured' keeps the full structure but drops redundant/derivable fields (absolute longitudes, element/modality, the precision audit rows) for a leaner machine payload. 'summary' returns only the high-signal essentials (luminaries + Ascendant, dominant element/modality, chart pattern, top aspects, precision status) to save tokens. Request 'summary' for a quick read, 'full' when you need every placement. | full |
| response_format | No | Output shape. 'markdown' is a readable briefing for display; 'json' returns the full structured chart for further processing. | markdown |
| verify_precision | No | When true (default), independently re-derives every planet with a second ephemeris and attaches a precision audit. Set false to skip the cross-check. |
Output Schema
| Name | Required | Description | Default |
|---|---|---|---|
| meta | Yes | ||
| houses | Yes | ||
| aspects | Yes | ||
| context | Yes | ||
| planets | Yes | ||
| precision | No |