# Astro Agents Western Synastry API

> Astro Agents Western Synastry API is a paid API for AI agents from astro-agents-api.vercel.app, paid per call via x402, $0.12/call, status unknown (last checked 2026-10-12).

Computes deterministic Western astrological synastry (compatibility) between two people using the NASA/JPL DE440 ephemeris, returning cross-aspects, orbs, and aspect counts.

## Facts

- Endpoint: POST https://astro-agents-api.vercel.app/v1/western/synastry?utm_source=zero.xyz
- Price: $0.12/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-12
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/astro-agents-western-synastry-api-5a2f98a4
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_O2NdLJ3RLuloSXGqme329

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability astro-agents-western-synastry-api-5a2f98a4 -d '<json body>'
```

Example prompt: Can you run a Western synastry comparison between person A born on June 15, 1990 at 8:30am in New York City (40.71°N, 74.01°W) and person B born on March 22, 1988 at 11:45pm in London (51.51°N, 0.13°W), using Placidus houses and tropical zodiac, and tell me how many harmonious vs challenging aspects they share?

## When to prefer this

Choose this endpoint when you need deterministic, reproducible astrological synastry calculations between two individuals using the NASA/JPL DE440 ephemeris with no LLM involvement — ideal for applications requiring auditable, hash-verifiable results. Prefer this over LLM-based astrology responses when precision, reproducibility, and Western tropical or sidereal methodology matter. Use when you need structured aspect data (orbs, exactness percentages, aspect types) rather than narrative interpretations.

## Known failure modes

- Missing required latitude/longitude for either person returns validation error
- Invalid or out-of-range date/time values cause parsing failure
- Unsupported house system or ayanamsa enum value returns schema validation error
- Orb values exceeding maximum of 15 degrees are rejected
- Ambiguous local time without timezone or time_basis may yield incorrect planetary positions
- Dates outside ephemeris range (1800–2200) will fail

## How this service works

Deterministic Western + Vedic astrology API for AI agents: JPL DE440 ephemeris, no LLM, reproducible SHA-256 hashes.

## Output

Returns a JSON object containing cross-aspects between the two charts (each with aspect type, angle, orb, orb allowed, and exactness percentage), summary counts of harmonious, challenging, and conjunction aspects, plus metadata including ephemeris source, engine version, determinism flag, and a SHA-256 hash of the result for reproducibility verification.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method",
    "bodyType",
    "body"
   ],
   "properties": {
    "body": {
     "type": "object",
     "required": [
      "person_a",
      "person_b"
     ],
     "properties": {
      "options": {
       "type": "object",
       "properties": {
        "orbs": {
         "type": "object",
         "additionalProperties": {
          "type": "number",
          "maximum": 15,
          "minimum": 0
         }
        },
        "points": {
         "oneOf": [
          {
           "enum": [
            "all"
           ],
           "type": "string"
          },
          {
           "type": "array",
           "items": {
            "enum": [
             "sun",
             "moon",
             "mercury",
             "venus",
             "mars",
             "jupiter",
             "saturn",
             "uranus",
             "neptune",
             "pluto",
             "mean_node",
             "true_node",
             "mean_lilith"
            ],
            "type": "string"
           }
          }
         ]
        },
        "zodiac": {
         "enum": [
          "tropical",
          "sidereal"
         ],
         "type": "string",
         "default": "tropical"
        },
        "aspects": {
         "oneOf": [
          {
           "enum": [
            "all"
           ],
           "type": "string"
          },
          {
           "type": "array",
           "items": {
            "enum": [
             "conjunction",
             "opposition",
             "trine",
             "square",
             "sextile",
             "quincunx",
             "semisextile",
             "semisquare",
             "sesquiquadrate",
             "quintile",
             "biquintile"
            ],
            "type": "string"
           }
          }
         ]
        },
        "ayanamsa": {
         "enum": [
          "fagan_bradley",
          "krishnamurti",
          "lahiri",
          "raman",
          "true_chitrapaksha",
          "yukteshwar"
         ],
         "type": "string",
         "default": "lahiri"
        },
        "house_system": {
         "enum": [
          "alcabitius",
          "campanus",
          "equal",
          "koch",
          "meridian",
          "morinus",
          "placidus",
          "porphyry",
   
… (truncated)
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "meta": {
   "engine": "astro-agents/1.0.0",
   "llm_used": false,
   "ephemeris": "NASA/JPL DE440 (1800-01-01..2200-01-01)",
   "deterministic": true,
   "result_sha256": "d73954df219854b1f2ad98476b58986d82ee19cfffc91b8adaea011df6eb4f01"
  },
  "endpoint": "western/synastry",
  "result_excerpt": {
   "aspect_counts": {
    "harmonious": 27,
    "challenging": 28,
    "conjunctions": 11
   },
   "cross_aspects": [
    {
     "orb": 0.192882,
     "angle": 180,
     "aspect": "opposition",
     "point_a": "a:true_node",
     "point_b": "b:mercury",
     "orb_allowed": 8,
     "exactness_pct": 97.6
    }
   ]
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/astro-agents-western-synastry-api-5a2f98a4/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from astro-agents-api.vercel.app](https://www.zero.xyz/host/astro-agents-api.vercel.app/llms.txt)