Declination & equation of time
API · /solarposition-api
Solar Position API
Solar-position astronomy as an API, computed locally and deterministically with the NOAA solar-calculator algorithm. The position endpoint gives the sun's elevation (altitude above the horizon), azimuth (clockwise from true north), zenith angle and hour angle for any latitude, longitude, date and local time with a UTC offset — telling you exactly where the sun is in the sky and whether it is above the horizon. The declination endpoint gives the solar declination — the sun's angle north or south of the equator, about +23.44° at the June solstice and −23.44° in December — and the equation of time, the difference between apparent and mean solar time, for any date. The solar-noon endpoint gives the local clock time of solar noon, the peak (noon) elevation 90 − |latitude − declination| and the day length, handling polar day and polar night. Latitudes and longitudes are in degrees (north and east positive), dates are YYYY-MM-DD and times HH:MM:SS local. Everything is computed locally and deterministically, so it is instant and private. Ideal for solar-tracking, PV-panel-orientation, photography golden-hour, agriculture, shading-analysis and astronomy app developers, sun-path and daylight tools, and STEM teaching. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is the sun's position in the sky; for sunrise and sunset clock times use a sunrise API and for solar irradiance and PV resource a solar-resource API.
API health
healthy- Uptime
- 100.00%
- Server probes · 24h
- Avg latency
- 87 ms
- Server probes · 24h
- Subscribers
- 4,086
- active
- Total calls
- 24
- last 7 days
Pricing
Pick a tier — billed monthly, cancel anytime.
Free
Free
- 3,000 calls / month
- 2 requests / second
- Hard cap (429 above quota, no overage)
- 3,000 calls/month
- 2 req/sec
- Position + declination + solar noon
- No credit card
Starter
€7.00 /month
- 40,000 calls / month
- 6 requests / second
- Hard cap (429 above quota, no overage)
- 40,000 calls/month
- 6 req/sec
- Elevation, azimuth, equation of time
- Email support
Pro
€18.00 /month
- 250,000 calls / month
- 15 requests / second
- Hard cap (429 above quota, no overage)
- 250,000 calls/month
- 15 req/sec
- Solar-tracking & PV-orientation pipelines
- Priority support
Mega
€55.00 /month
- 1,450,000 calls / month
- 40 requests / second
- Hard cap (429 above quota, no overage)
- 1,450,000 calls/month
- 40 req/sec
- Platform scale
- Dedicated SLA
Built by
Related APIs
Other APIs with overlapping tags.
Elevation API
Terrain elevation in metres above sea level for any coordinate — a single point or a batch of up to 50 points for route and grid profiles. Ideal for hiking and outdoor apps, mapping, drone flight planning, solar siting, flood and line-of-sight analysis.
api.oanor.com/elevation-api
Stellar Parallax API
Stellar-parallax and astrometry maths as an API, computed locally and deterministically. The distance endpoint turns a measured trigonometric parallax angle into a distance using d(pc) = 1/p(arcsec), accepting the parallax in arcseconds or milliarcseconds and returning the distance in parsecs, light-years and astronomical units — a parallax of one arcsecond is one parsec (≈3.2616 light-years) by definition, and Proxima Centauri’s 0.7687-arcsecond parallax gives about 1.30 pc, or 4.24 light-years. The parallax endpoint inverts it, p(arcsec) = 1/d(pc), giving the tiny annual back-and-forth angle a star traces against the background as Earth orbits the Sun. The proper-motion endpoint computes a star’s tangential (transverse) velocity across the sky from its proper motion and distance, v_t = 4.74047·μ(arcsec/yr)·d(pc) km/s — Barnard’s Star, with a proper motion of about 10.39 arcsec/yr at 1.83 pc, races across the sky at roughly 90 km/s. Everything is computed locally and deterministically, so it is instant and private. Ideal for astronomy, astrophysics, planetarium, education and science-communication app developers, star-distance and stellar-kinematics tools, and Gaia-catalogue post-processing. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is geometric distance and kinematics; for a star’s apparent and absolute brightness use a star-magnitude API.
api.oanor.com/parallax-api
Light Travel Time API
Light-travel-time astronomy maths as an API, computed locally and deterministically. The travel-time endpoint computes how long light takes to cross a distance, t = d/c with c = 299,792,458 m/s exactly, accepting the distance in metres, kilometres, miles, astronomical units, light-years, parsecs or light-seconds/minutes and returning the time in seconds, minutes, hours, days and years — light from the Sun reaches Earth in about 8.3 minutes and the nearest star is about 4.2 light-years away. The distance endpoint inverts the relation, d = c·t, to give how far light travels in a time, returning the distance in metres, kilometres, astronomical units, light-years and parsecs — one light-year is about 9.461×10¹⁵ m. The round-trip endpoint computes the one-way and round-trip communication delay to a target, d/c and 2·d/c, the light-speed latency that makes distant spacecraft control so slow and Mars rovers largely autonomous. Distance units include light-second and light-minute and time units run from seconds to years. Everything is computed locally and deterministically, so it is instant and private. Ideal for astronomy, space-mission, education, science-communication and simulation app developers, communication-delay and cosmic-distance tools, and physics teaching. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is light travel time; for an object's angular size use an angular-size API and for sidereal time a sidereal API.
api.oanor.com/lighttime-api
Angular Size API
Angular-size astronomy and optics maths as an API, computed locally and deterministically. The angular-size endpoint computes the angular diameter an object subtends, δ = 2·arctan(d/(2D)), from its physical size and its distance, returning the angle in radians, degrees, arcminutes and arcseconds, along with the small-angle approximation δ ≈ d/D — the Sun and Moon are each about half a degree (31 arcminutes) across. The distance endpoint inverts the relation, D = d/(2·tan(δ/2)), to give an object's distance from its known true size and its measured angular size, the basis of the standard-ruler distance method. The object-size endpoint computes an object's physical diameter, d = 2·D·tan(δ/2), from its distance and angular size. Size and distance use any one consistent unit, and angles may be given in radians, degrees, arcminutes or arcseconds. Everything is computed locally and deterministically, so it is instant and private. Ideal for astronomy, telescope, astrophotography, surveying and optics app developers, field-of-view and rangefinding tools, and physics education. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is angular size; for stellar magnitude and parallax distance use a star-magnitude API and for sidereal time a sidereal API.
api.oanor.com/angularsize-api
Frequently asked questions
Quick answers about pricing, quotas, and integration.
How do I get an API key for Solar Position API?
What's the rate limit for Solar Position API?
How much does Solar Position API cost?
Can I cancel my subscription anytime?
Is Solar Position API GDPR-compliant?
Pick an endpoint from the list on the left to see its details and try it.
Code snippets
Sign up to get an API key, then call any path under your slug.
curl https://api.oanor.com/solarposition-api/SOME_PATH \
-H "x-oanor-key: oanor_test_..."
const res = await fetch("https://api.oanor.com/solarposition-api/SOME_PATH", {
headers: { "x-oanor-key": "oanor_test_..." }
});
const data = await res.json();
$ch = curl_init("https://api.oanor.com/solarposition-api/SOME_PATH");
curl_setopt($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/solarposition-api/SOME_PATH",
headers={"x-oanor-key": "oanor_test_..."},
)
print(r.json())
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