561 Group Market

Astronomy Positions

Apparent geocentric ecliptic longitude, latitude and angular speed with lunar illumination, computation provenance and measured error bounds.

Price
$0.04 USDC per request
Network
Base mainnet, eip155:8453, settled in USDC through the Coinbase CDP facilitator
Method and URL
GET https://market.561.group/v1/astronomy/positions/{date}
Response type
application/json
Seller
Causeway Services (561 Group)

Input contract

Input that fails this contract is refused with a 4xx status before any payment is requested.

{
  "pathParamsSchema": {
    "type": "object",
    "properties": {
      "date": {
        "type": "string",
        "description": "Exact ISO-8601 UTC date or instant, e.g. 2026-07-21T00:00:00Z."
      }
    },
    "required": [
      "date"
    ]
  }
}

Example request

{
  "method": "GET",
  "url": "https://market.561.group/v1/astronomy/positions/2026-07-21T00:00:00Z",
  "headers": {
    "accept": "application/json"
  }
}

Output

{
  "schema": {
    "type": "object",
    "required": [
      "tier",
      "time",
      "frame",
      "bodies",
      "lunarPhase",
      "provenance",
      "accuracy"
    ],
    "properties": {
      "tier": {
        "const": "astronomy-positions"
      },
      "time": {
        "type": "string"
      },
      "frame": {
        "type": "string"
      },
      "bodies": {
        "type": "object"
      },
      "lunarPhase": {
        "type": "object"
      },
      "provenance": {
        "type": "object"
      },
      "accuracy": {
        "type": "object"
      }
    }
  },
  "example": {
    "tier": "astronomy-positions",
    "time": "2026-07-21T00:00:00.000Z",
    "frame": "geocentric ecliptic-of-date, tropical, apparent",
    "bodies": {
      "sun": {
        "longitude": 118.3151,
        "latitude": 0,
        "speed": 0.95465
      }
    },
    "lunarPhase": {
      "elongation": 92.4413,
      "illuminatedFraction": 0.566,
      "trend": "waxing"
    },
    "provenance": {
      "algorithm": "meeus-truncated-series + jpl-approximate-elements (zero-dependency)"
    },
    "accuracy": {
      "validRange": "1800-2050",
      "method": "independently audited against astronomy-engine (VSOP87/ELP)"
    }
  }
}

How to buy with x402

  1. Send the request without payment. The server answers 402 Payment Required with a base64 JSON PAYMENT-REQUIRED header holding the amount, asset, network and payee.
  2. Have your wallet sign an EIP-3009 transferWithAuthorization for exactly those terms (an x402 client library does this for you).
  3. Repeat the identical request with the signed payload in the PAYMENT-SIGNATURE header.
  4. The server verifies, runs the operation, settles, and returns 200 with the result and a PAYMENT-RESPONSE header carrying the settlement receipt.

Read the price without paying

curl --include --request GET --header 'accept: application/json' --url 'https://market.561.group/v1/astronomy/positions/2026-07-21T00:00:00Z'

This request authorizes nothing; it returns the live payment terms. Read the full explanation of x402.

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