comparative

Calculate Composite

Calculate a composite chart from 2–10 subjects. The default method, davison (also accepted as davidson, the spelling this API originally shipped), computes a true Davison relationship chart: a real chart cast at the mean of the subjects' birth instants and the great-circle midpoint of their birth places, with real planets, angles, and house cusps. method=midpoint instead averages each body's longitude across the subjects; a midpoint composite has no Ascendant or Midheaven, so its angles and house cusps are empty. The response's method field reports which was actually computed.

🤖 AI-optimized output available — add format=llm to reduce payload ~65%.

post/comparative/composite

Request

  • Base URL: https://api.openephemeris.com
  • URL: https://api.openephemeris.com/comparative/composite
  • Auth: one of:
    • HTTP bearer
    • API key in header X-OpenEphemeris-API-Key
    • API key in header X-API-Key
    • API key in header X-Service-Key

Query parameters

output_modestring nullable

Deprecated: use preset+format. Accepts full|simple|llm.

formatstring

Request body

include_visualboolean

If true, a full visual SVG or PNG output will be rendered and returned alongside the chart data. Note: Visuals incur a +2 credit surcharge.

method'davidson' | 'davison' | 'midpoint'

Example request

{
  "method": "davidson",
  "subjects": [
    {
      "birth_datetime": {
        "iso": "1990-06-15T14:30:00"
      },
      "birth_location": {
        "latitude": {
          "decimal": 40.7128
        },
        "longitude": {
          "decimal": -74.006
        },
        "timezone": {
          "iana_name": "America/New_York"
        }
      },
      "name": "Alice"
    },
    {
      "birth_datetime": {
        "iso": "1992-02-10T09:15:00"
      },
      "birth_location": {
        "latitude": {
          "decimal": 34.0522
        },
        "longitude": {
          "decimal": -118.2437
        },
        "timezone": {
          "iana_name": "America/Los_Angeles"
        }
      },
      "name": "Bob"
    }
  ]
}

Response

Successful Response

chart_typestring

Chart type identifier

element_balanceobject

Elemental balance

elongationsobject

Sun-relative elongations (per-body separation and signed east/west delta) (opt-in).

harmonicsobject

Harmonic chart positions keyed by harmonic number

hemisphere_emphasisobject

Hemisphere weights

human_design_gatesobject

Human Design / I Ching gate + line mappings from ecliptic longitude (math-only; includes mapping version) (opt-in).

lunar_phaseobject

Lunar phase context (phase name, illumination, phase angle, waxing/waning, days-to-new/full) (opt-in).

midpointsobject[]

Calculated midpoints between planet pairs

patterns_by_typeobject

Patterns organized by type for easier filtering

planetsobject required

Planetary positions keyed by name

solar_relationshipsobject

Solar relationship / visibility classifications (e.g., cazimi/combust/under-beams) and Mercury/Venus morning/evening star context.

successboolean

Response success status

void_of_courseobject

Void-of-Course Moon context (status, start/end window, last major aspect, sign context) (opt-in).

Example response

{
  "calculation_metadata": {
    "technique_id": "natal",
    "technique_label": "Composite (Davison)",
    "technique_method": "davidson",
    "technique_version": "v1"
  }
}

Changes

No recorded changes to this operation across all 1 revision of this API.