---
title: "Western Synastry"
method: POST
path: "/v1/western/synastry"
tags: ["Western Astrology"]
---

# Western Synastry

`POST /v1/western/synastry`

## Request

- Base URL: `https://api.asterwise.com`
- URL: `https://api.asterwise.com/v1/western/synastry`
- Auth: HTTP bearer

Aspect grid between two natal charts using the tropical zodiac. Returns all inter-chart aspects using standard modern Western orbs. Useful for relationship compatibility analysis.

## Request body

- TwoPersonRequest
  - `person1` WesternBirthInput, required: Birth input for Western endpoints: the tropical zodiac is always used.
    - `location` string, nullable: City name to resolve to lat/lon/tz automatically. Example: 'Mumbai' or 'New Delhi, India'. If provided, latitude, longitude and timezone are not required.
    - `name` string: Person name associated with the birth record
    - `date` string, required: Birth date in YYYY-MM-DD format
    - `time` string, nullable: Birth time in HH:MM 24-hour format. If omitted, the chart is cast for 06:00 local time (not a sunrise chart) and birth_time_provided is false: houses, the Ascendant, the sect and the Moon's exact degree are then approximate.
    - `latitude` number, nullable: Latitude. Required if location not provided.
    - `longitude` number, nullable: Longitude. Required if location not provided.
    - `timezone` string, nullable: IANA timezone. Required if location not provided (unless utc_offset is given). For dates before the zone adopted a standard time, the birthplace's local mean time (longitude / 15 hours) is used.
    - `utc_offset` string, nullable: Optional explicit UTC offset of the birth time, as ±HH:MM or ±HH:MM:SS (e.g. '+04:51:31' for Bombay mean time). Overrides the offset `timezone` would give. Use it when the birth record states the offset, or for historical local times the IANA database cannot represent.
    - `ayanamsa` 'lahiri' | 'raman' | 'kp' | 'tropical': Ignored on Western endpoints: positions are always tropical (no ayanamsa). Accepted so one birth object can be sent to Vedic and Western endpoints alike.
  - `person2` WesternBirthInput, required: Birth input for Western endpoints: the tropical zodiac is always used.
    - `location` string, nullable: City name to resolve to lat/lon/tz automatically. Example: 'Mumbai' or 'New Delhi, India'. If provided, latitude, longitude and timezone are not required.
    - `name` string: Person name associated with the birth record
    - `date` string, required: Birth date in YYYY-MM-DD format
    - `time` string, nullable: Birth time in HH:MM 24-hour format. If omitted, the chart is cast for 06:00 local time (not a sunrise chart) and birth_time_provided is false: houses, the Ascendant, the sect and the Moon's exact degree are then approximate.
    - `latitude` number, nullable: Latitude. Required if location not provided.
    - `longitude` number, nullable: Longitude. Required if location not provided.
    - `timezone` string, nullable: IANA timezone. Required if location not provided (unless utc_offset is given). For dates before the zone adopted a standard time, the birthplace's local mean time (longitude / 15 hours) is used.
    - `utc_offset` string, nullable: Optional explicit UTC offset of the birth time, as ±HH:MM or ±HH:MM:SS (e.g. '+04:51:31' for Bombay mean time). Overrides the offset `timezone` would give. Use it when the birth record states the offset, or for historical local times the IANA database cannot represent.
    - `ayanamsa` 'lahiri' | 'raman' | 'kp' | 'tropical': Ignored on Western endpoints: positions are always tropical (no ayanamsa). Accepted so one birth object can be sent to Vedic and Western endpoints alike.

## Response `200`

Successful Response

- ApiResponseSynastryResponse
  - `success` boolean: True if the request succeeded
  - `message` string: Human-readable status message
  - `data` SynastryResponse, required
    - `birth_time_provided` boolean: True only when both people supplied a birth time. See person1_birth_time_provided and person2_birth_time_provided.
    - `person1_birth_time_provided` boolean: True when person 1 supplied a birth time.
    - `person2_birth_time_provided` boolean: True when person 2 supplied a birth time.
    - `aspects` SynastryAspectSchema[], required
      - `person1_planet` string, required
      - `person2_planet` string, required
      - `type` string, required
      - `exact_angle` number, required
      - `orb` number, required
    - `total_aspects` integer, required

## Other responses

- `401`: Authentication failed
- `403`: Authorization failed
- `404`: Resource not found
- `413`: Payload too large
- `422`: Validation error
- `429`: Rate limit exceeded
- `500`: Internal error
- `502`: Upstream provider error
- `503`: Service unavailable

---

[API](https://skmtc.dev/asterwise/apis/asterwise-api.md) · [All operations](https://skmtc.dev/asterwise/apis/asterwise-api/llms.txt) · [OpenAPI document](https://skmtc.dev/asterwise/apis/asterwise-api/revisions/3c4bbb1194e2?raw)