---
title: "Compute where any asteroid or comet is in the sky and..."
method: GET
path: "/api/space/observe"
tags: ["space"]
---

# Compute where any asteroid or comet is in the sky and...

`GET /api/space/observe`

## Request

- Base URL: `https://2s.io`
- URL: `https://2s.io/api/space/observe`
- Auth: API key in header `PAYMENT-SIGNATURE`

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.

## Query parameters

- `body` string, required
- `lat` number
- `lon` number
- `altKm` number
- `at` string, date-time
- `trial` 1

## Other responses

- `200` (unresolved $ref)
- `400`: Invalid request — not charged. error.code: BAD_REQUEST or INVALID_PARAM (parameter validation; error.details.issues lists each problem), MALFORMED_JSON, or a request-specific code. Other client errors: 405 METHOD_NOT_ALLOWED (wrong verb; see the Allow header), 413 PAYLOAD_TOO_LARGE.
- `402`: Payment required. Body is the x402 PaymentRequirements envelope with a multi-network accepts array; the per-call price is in accepts[].amount (and on the operation as x-2s-price). Sign for whichever rail you hold USDC on (EIP-3009 for Base, partial SPL transfer for Solana) and retry with the PAYMENT-SIGNATURE header (X-PAYMENT also accepted for v1 clients). Also PAYMENT_SETTLE_FAILED (error envelope) when a verified payment failed to settle: error.details.chargeStatus is "not_charged" (retry with a fresh payment) or "unknown" (the authorization may still settle before its deadline — check it before retrying).
- `404`: Not found — NOT_FOUND (or NO_SOURCES / NO_OPINIONS): the requested entity does not exist. Not charged.
- `429`: Too many requests — RATE_LIMITED: our per-IP / per-payer limiter. Not charged; retry after Retry-After.
- `5XX`: Server-side failure. 500 INTERNAL: unexpected error; quote error.errorId (also the X-2s-Error-Id header). 502 UPSTREAM_UNAVAILABLE (or another UPSTREAM_* code): the data provider failed — composite endpoints refuse unbilled when every source fails. 503 SERVICE_PAUSED: endpoint paused by the operator kill switch, retry after Retry-After; 503 SPEND_CAP: daily upstream budget exhausted. 504 UPSTREAM_TIMEOUT. Not charged.

---

[API](https://skmtc.dev/2s-io/apis/2s-the-most-everything-api.md) · [All operations](https://skmtc.dev/2s-io/apis/2s-the-most-everything-api/llms.txt) · [OpenAPI document](https://skmtc.dev/2s-io/apis/2s-the-most-everything-api/revisions/da4c5caf686e?raw)