Chart geometry · ChronOS guide
Astrological house systems as explicit calculation models
An astrological house calculation divides the local celestial sphere according to a named convention. The result depends on the exact time, geographic location, Earth orientation and selected house system. Different systems are alternative models, not interchangeable formatting choices.
01 / Method
Inputs and model boundaries
House cusps require a known time and observer location. Some quadrant systems become singular or unstable at particular latitudes. A production engine should report the requested and actually used system instead of silently substituting another result.
ChronOS carries the house-system choice in chart requests and response metadata. The capability registry identifies the systems enabled by the current release.
- Exact UTC instant
- WGS84 latitude and longitude
- Named house system
- Documented polar and fallback behavior
02 / API example
Calculate a chart with houses
House calculations are part of the high-level chart operation. The location belongs to the chart moment rather than an implicit account default.
curl --request POST \
--url https://api.chronos-ephemeris.com/v2/charts/calculate \
--header "Authorization: Bearer $CHRONOS_API_KEY" \
--header "Content-Type: application/json" \
--data '{
"chart_type": "natal",
"house_system": "placidus",
"primary": {
"datetime_utc": "1990-01-01T12:00:00Z",
"location": { "latitude": 52.52, "longitude": 13.405 }
}
}'Keep API keys in server-side secret storage. The example uses an environment variable and contains no production credential.
03 / Evidence
Testing house cusps
House validation should include ordinary and high-latitude locations, cusp normalization, angular ordering and reference fixtures for every advertised system. Small convention differences can be legitimate and must be documented.
ChronOS includes house-system fixtures in its release validation and exposes requested-versus-used system fields where a calculation contract permits fallback behavior.
04 / Applications
House-system use cases
Houses are an astrology-specific layer placed above the astronomical instant and observer geometry.
- Natal and transit charts
- Synastry and composite charts
- House-ingress event searches
- Rendered chart wheels
05 / FAQ
Frequently asked questions
Which house system is most accurate?+
House systems encode different astrological conventions, so there is no single astronomical accuracy ranking that selects one for every practice.
Why do house cusps require a location?+
Houses are based on the local orientation of the celestial sphere, which changes with latitude, longitude and time.
What happens near polar latitudes?+
Some house systems have mathematical limitations at high latitudes. Applications should inspect warnings and the returned requested-versus-used system instead of assuming every model is always defined.