space.observe

Compute where any asteroid or comet is in the sky and whether you can see it. Give a body (designation/number/name, e.g. "433 Eros", "Ceres", "2024 YR4") and optionally your lat/lon and a time (ISO, default now). Returns the body's identity (NEO/PHA flags, orbit class, absolute magnitude H), its geocentric right ascension + declination, the constellation it's in, geocentric + heliocentric distance (AU), solar phase angle, and its apparent visual magnitude (IAU H-G model — how bright it appears now). With lat/lon it adds altitude/azimuth, whether it's above your horizon, a visible-now flag (up AND sky dark), and the best viewing window in the next 24 hours (when it's highest during darkness). Orbital position is computed locally from JPL elements — VALIDATED against JPL Horizons to <0.1 arcminute. Stargazing, astrophotography planning, occultation/observation prep. For the body's static physical + orbital params see /api/space/body.

price
$0.0029 USDC per call
method
GET/api/space/observe
payment
x402 v2 · USDC on Base (EIP-3009) or Solana (SPL transfer)
auth
None. Sign the payment, retry with PAYMENT-SIGNATURE.

Overview

The observe API is a pay-per-call space endpoint built for AI agents and autonomous software. Compute where any asteroid or comet is in the sky and whether you can see it.

There is no signup and no API key. An agent (or any HTTP client) hits the endpoint, receives an x402 "402 Payment Required" challenge, signs a sub-cent USDC payment on Base or Solana, and retries — the data comes back on the paid request. That makes it a drop-in observe data source for an agent tool-use loop, an MCP host, or a backend that needs space data on demand without onboarding to yet another vendor portal.

Use cases

Parameters

NameTypeDescription
bodyrequiredstring
min 1 chars · max 60 chars
latnumber
min -90 · max 90
lonnumber
min -180 · max 180
altKmnumber
min -0.5 · max 9
atstring
date-time

Code samples

cURLbash
# 1. Probe with no auth → 402 envelope with PaymentRequirements
curl -sS 'https://2s.io/api/space/observe?body=example&lat=-90&lon=-180&altKm=-0.5&at=example'

# 2. Sign + retry with PAYMENT-SIGNATURE:
curl -sS 'https://2s.io/api/space/observe?body=example&lat=-90&lon=-180&altKm=-0.5&at=example' \
  -H 'PAYMENT-SIGNATURE: <base64-json-payload>'

# Or use the canonical runner (handles probe → sign → retry):
#   EVM_PRIVATE_KEY=0x... node --env-file=.env.local \
#     --experimental-strip-types scripts/x402-pay.ts \
#     'https://2s.io/api/space/observe?body=example&lat=-90&lon=-180&altKm=-0.5&at=example'
TypeScript / Node — @2sio/sdktypescript
import { TwoS } from '@2sio/sdk'

const client = new TwoS({
  privateKey: process.env.EVM_PRIVATE_KEY as `0x${string}`,
})

const result = await client.space.observe({
  "body": "example",
  "lat": -90,
  "lon": -180,
  "altKm": -0.5,
  "at": "example"
})

console.log('endpoint:', result.endpoint)
console.log('cost:', result.costUsd, 'USDC')
console.log('tx:', result.settlement?.txHash)
console.log('data:', result.data)
Python — 2siopython
import os
from twosio import TwoS

client = TwoS(private_key=os.environ["EVM_PRIVATE_KEY"])

result = client.space.observe(body="example", lat=-90, lon=-180, altKm=-0.5, at="example")

print("endpoint:", result.endpoint)
print("cost:", result.cost_usd, "USDC")
print("tx:", (result.settlement or {}).get("tx_hash"))
print("data:", result.data)
MCP — Claude Desktop / AgentKit / any MCP hostjson
// 1. Add @2sio/mcp to your MCP host config (Claude Desktop example below).
//    EVM_PRIVATE_KEY funds x402 payments per call.

// claude_desktop_config.json
{
  "mcpServers": {
    "2sio": {
      "command": "npx",
      "args": ["-y", "@2sio/mcp"],
      "env": { "EVM_PRIVATE_KEY": "0x..." }
    }
  }
}

// 2. Once the server is running, agents call this tool via standard MCP:

{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/call",
  "params": {
    "name": "space.observe",
    "arguments": {
      "body": "example",
      "lat": -90,
      "lon": -180,
      "altKm": -0.5,
      "at": "example"
    }
  }
}

Response

FieldTypeDescription
okboolean
one of: true
itemsarray
totalintegerTotal matching rows upstream; null when unknown.
sourceobject
Example response datajson
{
  "ok": true,
  "items": [
    {
      "body": {
        "fullName": "example",
        "neo": false,
        "pha": false,
        "orbitClass": "example",
        "absoluteMagnitudeH": 1
      },
      "at": "example",
      "position": {
        "rightAscensionHours": 1,
        "declinationDeg": 1,
        "constellation": "example",
        "geocentricDistanceAu": 1,
        "heliocentricDistanceAu": 1,
        "phaseAngleDeg": 1,
        "apparentMagnitude": 1
      },
      "observer": {
        "altitudeDeg": 1,
        "azimuthDeg": 1,
        "aboveHorizon": false,
        "visibleNow": false,
        "bestViewing": {
          "at": "example",
          "altitudeDeg": 1
        }
      }
    }
  ],
  "total": 1,
  "source": {
    "provider": "example",
    "url": "example",
    "license": "example"
  }
}

FAQ

Do I need an API key to use the observe API?
No. space.observe is x402-native — there is no signup and no API key. Your client makes the call, receives a 402 with payment requirements, signs a USDC payment, and retries. Funds come from a wallet you control.
How much does the observe API cost?
$0.00288 USDC per call, charged per request. There are no monthly fees, seats, or minimums — you pay only for the calls you make.
Can I try the observe API for free first?
Yes. Add ?trial=1 (or the header X-2s-Trial: 1) to get a free real call per endpoint per hour, so you can verify the response shape before wiring payment.
Which networks and tokens are supported?
USDC on Base (via EIP-3009 transferWithAuthorization) or Solana (SPL transfer), using the open x402 payment protocol.
How do I call space.observe from an AI agent or MCP host?
Use @2sio/sdk (TypeScript), 2sio (Python), or the @2sio/mcp server for any MCP host — each handles the probe → sign → retry loop for you. See the code samples on this page.

Discovery

Related: observe api · space observe api · observe api for ai agents · x402 space api · observe api no api key · pay per call observe api · space api