API · /astronomy-api

Astronomy API

healthy 3,300 Subscribers

A fast, fully-local astronomy and ephemeris engine: compute the equatorial (right-ascension/declination) and horizontal (azimuth/altitude) positions of the Sun, Moon and all planets for any observer and moment, get precise rise, set and transit (culmination) times for any body, read detailed lunar state (phase angle, named phase, illuminated fraction, apparent magnitude, geocentric distance, age since the last new moon and the dates of the next new/first-quarter/full/last-quarter moons), and list the exact equinoxes and solstices of any year. Every endpoint accepts input via the query string or the request body. Pure server-side computation (no third-party upstream), so responses are instant and always available. Ideal for weather and tide apps, astrophotography planners, calendars, solar/energy tools, Islamic and lunar calendars, and education.

#astronomy #ephemeris #moon-phase #sunrise-sunset #planets #space #science #dev-tools

api.oanor.com/astronomy-api

Get an API key Try in playground → Contact provider

Machine-readable spec so AI agents can integrate this API.

/api/astronomy-api/openapi.json

/api/astronomy-api/llms.txt

Discovery: GET /api/index.json lists every API.

Astronomy API — live data on the oanor API marketplace

API health

healthy

Uptime: 100.00%; Server probes · 24h
Avg latency: 76 ms; Server probes · 24h
Subscribers: 3,300; active
Total calls: 80; last 7 days

Full status page → · 16 probes/24h

Pricing

Pick a tier — billed monthly, cancel anytime.

Free

10,000 calls / month
2 requests / second
Hard cap (429 above quota, no overage)
10,000 calls/month, 2 req/s
Sun/Moon/planet positions, rise-set, moon phase & seasons
No credit card

Basic

€9.00 /month

150,000 calls / month
10 requests / second
Hard cap (429 above quota, no overage)
150,000 requests/month, 10 req/s
All endpoints, full planet set & detailed lunar data
Commercial use included
Email support

Pro

€29.00 /month

1,000,000 calls / month
25 requests / second
Hard cap (429 above quota, no overage)
1,000,000 requests/month, 25 req/s
High throughput for apps & batch ephemeris
Priority email support
Commercial use allowed

Mega

€79.00 /month

5,000,000 calls / month
100 requests / second
Hard cap (429 above quota, no overage)
5,000,000 requests/month, 100 req/s
Highest throughput for planners & data pipelines
Priority support
Commercial use allowed

Built by

PremiumApi

Related APIs

Other APIs with overlapping tags.

Meteorites API

NASA's catalogue of 45,000+ meteorites recovered on Earth as an API. For each meteorite: its name, NASA id, classification (recclass, e.g. L5, Iron), mass in grams, whether it was seen to fall or simply found, the year, and the latitude/longitude where it was recovered. Look one up by name or id, find the meteorites NEAR any coordinate (great-circle distance), rank by mass or year, list a classification or year, or search. Great for space, education, mapping and museum apps. Distinct from asteroids and close-approach data — these are rocks already on the ground.

api.oanor.com/meteorites-api

Constellations API

The 88 modern IAU constellations as an API — the reference an astronomy app, planetarium or education tool needs. For each constellation: its official IAU abbreviation, English name, the Latin genitive used when naming stars (e.g. "Alpha Andromedae"), a size rank, the approximate centre in equatorial coordinates (right ascension / declination) and the constellation name in roughly 25 languages. Look one up by abbreviation or name, search across every language, find which constellation a sky position falls nearest to, or list them all. Distinct from stars-api (individual stars) — this is the reference for the constellations themselves. Served from memory — always fast.

api.oanor.com/constellations-api

Observatory Codes API

The IAU Minor Planet Center list of observatory codes as an API — every site the MPC uses to identify a telescope when it publishes astrometric observations of asteroids and comets. For each of 2,700+ codes: the 3-character code, the observatory name, its east longitude and the parallax constants (rho·cos φ', rho·sin φ'). From those constants the API derives each site's geocentric latitude and a -180..180 longitude, so you can find the observatories nearest any point on Earth with a great-circle (haversine) search. Look one up by code, search by name, list them all, or find the closest sites to a latitude/longitude. Distinct from telescope-api (optics maths) — this is the registry of real observing sites and where they are. Served from memory — always fast.

api.oanor.com/observatories-api

Sundial API

Sundial gnomonics maths as an API, computed locally and deterministically — the hour-line, gnomon and longitude-correction numbers a dial maker, horologist or astronomy hobbyist lays a sundial out with. The hour-line-angle endpoint gives the angle of each hour line on the dial plate, measured from the noon line: for a horizontal dial tan(angle) = sin(latitude) × tan(hour angle), and for a vertical south-facing dial cos(latitude) is used instead, where the hour angle is 15° per hour from solar noon. At 50° latitude the 1-o'clock line sits about 11.6° from noon rather than 15° — the lines bunch near noon and spread toward the ends, which is exactly why a sundial's hours are unevenly spaced. The gnomon endpoint gives the style angle: the gnomon's shadow-casting edge must point at the celestial pole, so it rises at the latitude angle on a horizontal dial (50° at 50° N) and at 90° − latitude on a vertical dial — get this wrong and the dial keeps correct time at only one season. The longitude-correction endpoint converts the dial's local apparent time to clock time: 4 minutes of time per degree of longitude, correction = 4 × (reference meridian − local longitude), so a dial at 7.5° E on Central European Time reads 30 minutes slow versus the clock. Everything is computed locally and deterministically, so it is instant and private. Ideal for sundial-design and gnomonics tools, astronomy-education and maker apps, and horology calculators. Pure local computation — no key, no third-party service, instant. Add the equation of time for full clock accuracy. 3 compute endpoints. For the sun's position use a solar-position API; for sunrise and sunset a sunrise API.

api.oanor.com/sundial-api

Frequently asked questions

Quick answers about pricing, quotas, and integration.

How do I get an API key for Astronomy API?

Sign up for free at oanor.com, generate an API key from the developer dashboard, and call Astronomy API with the x-oanor-key header. No credit card needed for the free tier.

What's the rate limit for Astronomy API?

Free tier allows 1 request per second. Paid plans scale up to 50 requests per second on the Mega tier. Hard limits return HTTP 429 above the quota — no surprise overage charges.

How much does Astronomy API cost?

Astronomy API has a free tier with 100 calls / month. Paid plans start at €9.00 / month with higher quotas and faster rate limits.

Can I cancel my subscription anytime?

Yes. Plans are billed monthly and you can cancel anytime from your billing dashboard. No long-term contracts and no cancellation fee.

Is Astronomy API GDPR-compliant?

All requests to Astronomy API go through our EU-based gateway. Your upstream API key never leaves our server and no personal data is shared with the upstream provider beyond the request you send.

Astronomy 4

Pick an endpoint from the list on the left to see its details and try it.

GET /v1/moon

Detailed lunar phase & next phases

Playground

Parameters

Custom headers

Language: Client:

GET /v1/positions

Body positions (equatorial + horizontal)

Playground

Parameters

Custom headers

Language: Client:

GET /v1/rise-set

Rise, set and transit for a body

Playground

Parameters

Custom headers

Language: Client:

GET /v1/seasons

Equinoxes & solstices of a year

Playground

Parameters

Custom headers

Language: Client:

Code snippets

curl https://api.oanor.com/astronomy-api/SOME_PATH \
  -H "x-oanor-key: oanor_test_..."

const res = await fetch("https://api.oanor.com/astronomy-api/SOME_PATH", {
  headers: { "x-oanor-key": "oanor_test_..." }
});
const data = await res.json();

$ch = curl_init("https://api.oanor.com/astronomy-api/SOME_PATH");
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_HTTPHEADER, ["x-oanor-key: oanor_test_..."]);
$response = curl_exec($ch);

import requests
r = requests.get(
    "https://api.oanor.com/astronomy-api/SOME_PATH",
    headers={"x-oanor-key": "oanor_test_..."},
)
print(r.json())

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Astronomy API

API health

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Related APIs

Meteorites API

Constellations API

Observatory Codes API

Sundial API

Frequently asked questions

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