USNO Astronomical Applications API
by aa.usno.navy.mil
Weather forecasts
Added on November 1st, 2026
Visit aa.usno.navy.mil →
What it does
The Astronomical Applications API of the US Naval Observatory gives sun and moon data for any place and date: rise, set and transit times, twilight, moon phase and illumination. Other endpoints list the moon phases of a year, equinoxes and solstices, solar eclipses, daylight saving time dates, sidereal time and Julian dates. Requests are plain GET calls that return JSON or GeoJSON. Free, no key needed.
At a glance
- API key
- Not needed · More APIs with no key
- Pricing
- Free, no key needed.
- From the browser
- Yes (CORS)
- Formats
- JSON
- Interface
- REST, HTTP-GET
- Provider
- aa.usno.navy.mil
More information: https://aa.usno.navy.mil/data/api
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Example request
curl
curl 'https://aa.usno.navy.mil/api/rstt/oneday?date=2026-11-01&coords=51.5,-0.12'JavaScript
const response = await fetch("https://aa.usno.navy.mil/api/rstt/oneday?date=2026-11-01&coords=51.5,-0.12");
const data = await response.json();
console.log(data);Python
import requests
response = requests.get(
"https://aa.usno.navy.mil/api/rstt/oneday?date=2026-11-01&coords=51.5,-0.12",
timeout=30,
)
print(response.json())The JavaScript works in a web page as well as in Node.js 18 or newer.