# Astro Agents Western Synastry API

> Astro Agents Western Synastry API is a paid API for AI agents from astro-agent.dev, paid per call via x402, $0.12/call, status unknown (last checked 2026-10-11).

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

## Facts

- Endpoint: POST https://astro-agent.dev/v1/western/synastry?utm_source=zero.xyz
- Price: $0.12/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-11
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/astro-agents-western-synastry-api-d762b7be
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_HDN9xSqBsaJLeT81EWMbf

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-d762b7be -d '<json body>'
```

Example prompt: Can you calculate the Western synastry between Alice, born on March 15 1990 at 2:30pm in New York (40.71° N, 74.01° W), and Bob, born on July 22 1988 at 11:00am in London (51.51° N, 0.13° W), using Placidus houses and tropical zodiac, and show me all their cross-aspects?

## When to prefer this

Choose this endpoint when you need reproducible, deterministic synastry computations grounded in real ephemeris data (NASA/JPL DE440) rather than LLM-generated or approximate astrological interpretations. Ideal when verifiability matters (SHA-256 hashes allow result auditing), when both Western and Vedic zodiac systems need to be supported, or when you want fine-grained control over house systems, aspect filters, orb sizes, and specific planetary points. Prefer over generic astrology APIs when precision, reproducibility, and agent-friendly structured output are required.

## Known failure modes

- Missing required latitude or longitude for either person returns a validation error
- Invalid date or time format causes parsing failure
- Requesting an unsupported house system or ayanamsa enum value returns a 400 error
- Dates outside the JPL DE440 ephemeris range (1800–2200) may return an out-of-range error
- Invalid orb values exceeding the maximum of 15 degrees return a validation error
- Payment not included or insufficient USDC causes a 402 payment required error

## How this service works

Synastry: Relationship comparison: cross-aspects, house overlays both ways, composite midpoints.

## Output

Returns a JSON object containing: a meta block with engine version, ephemeris details, determinism flag, and a reproducible SHA-256 hash of the result; an endpoint label; and a result excerpt with aspect_counts (harmonious, challenging, conjunctions) and an array of cross_aspects, each detailing the aspect type, angle, orb, orb_allowed, points involved, and exactness percentage.

## 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/1.0.3",
   "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-d762b7be/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from astro-agent.dev](https://www.zero.xyz/host/astro-agent.dev/llms.txt)