561 Group Market

DE440 Celestial Positions

JPL DE440 apparent celestial positions at an exact UTC instant, with distance, light time, declination, lunar nodes and cross-engine measurement evidence.

Price
$0.32 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/precision-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.

{
  "querySchema": {
    "type": "object",
    "properties": {
      "latitude": {
        "type": "number",
        "minimum": -90,
        "maximum": 90,
        "description": "Geodetic degrees north."
      },
      "longitude": {
        "type": "number",
        "minimum": -180,
        "maximum": 180,
        "description": "Geodetic degrees east."
      }
    },
    "required": [
      "latitude",
      "longitude"
    ]
  },
  "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/precision-positions/2026-07-21T00:00:00Z?latitude=41.8781&longitude=-87.6298",
  "headers": {
    "accept": "application/json"
  }
}

Output

{
  "schema": {
    "type": "object",
    "required": [
      "tier",
      "time",
      "location",
      "metrology",
      "bodies",
      "nodes"
    ],
    "properties": {
      "tier": {
        "const": "astronomy-precision-positions"
      },
      "time": {
        "type": "string"
      },
      "location": {
        "type": "object"
      },
      "metrology": {
        "type": "object"
      },
      "bodies": {
        "type": "array"
      },
      "nodes": {
        "type": "object"
      },
      "essentialsCrossCheck": {
        "type": "object"
      }
    }
  },
  "example": {
    "tier": "astronomy-precision-positions",
    "time": "2026-07-21T00:00:00.000Z",
    "location": {
      "latitudeDegreesNorth": 41.8781,
      "longitudeDegreesEast": -87.6298
    },
    "metrology": {
      "ephemeris": "JPL DE440",
      "supplier": "OxiEphemeris 0.1.1"
    },
    "bodies": [
      {
        "body": "Sun",
        "lon_deg": 118.28082814466296,
        "lat_deg": -0.0000954,
        "distance_au": 1.0160791606164674
      }
    ],
    "nodes": {
      "mean_node_deg": 331.52801390791086,
      "true_node_deg": 330.2782328236698
    }
  }
}

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/precision-positions/2026-07-21T00:00:00Z?latitude=41.8781&longitude=-87.6298'

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

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