#astronomy

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

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

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 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

Telescope optics maths as an API, computed locally and deterministically — the magnification, exit-pupil and resolving-power numbers an amateur astronomer or stargazing-app developer picks gear and eyepieces with. The magnification endpoint gives magnification = the telescope's focal length ÷ the eyepiece focal length (a 1000 mm scope with a 10 mm eyepiece is 100×), the focal ratio, and — from the aperture — the useful range from about the aperture in mm ÷ 7 (lowest useful, a 7 mm exit pupil) up to roughly 2× the aperture in mm, beyond which the image only dims and blurs; pass an eyepiece apparent field and it returns the true field of view. The exit-pupil endpoint gives aperture ÷ magnification, the width of the light beam leaving the eyepiece — a big 4–7 mm exit pupil for bright wide views of nebulae, a small 0.5–2 mm for the Moon and planets at high power. The resolution endpoint gives the Dawes limit ≈ 116 ÷ aperture(mm) and the slightly stricter Rayleigh limit ≈ 138 ÷ aperture in arcseconds, plus the limiting magnitude ≈ 2.7 + 5·log₁₀(aperture mm) — bigger glass splits finer doubles and reaches fainter stars, though seeing usually caps real resolution near 1 arcsecond. Everything is computed locally and deterministically, so it is instant and private. Ideal for astronomy and stargazing apps, telescope-shop and eyepiece-calculator tools, and observing-planner utilities. Pure local computation — no key, no third-party service, instant. 3 compute endpoints. For camera/thin-lens imaging use a lens API; for stellar magnitudes a star-magnitude API.

api.oanor.com/telescope-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 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 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

Sidereal-time astronomy as an API, computed locally and deterministically. The gmst endpoint computes the Greenwich Mean Sidereal Time for a UT date and time, GMST = 18.697374558 + 24.06570982441908·(JD − 2451545.0) hours modulo 24, returning it in hours, degrees and hours-minutes-seconds together with the Julian Day — sidereal time tracks the stars rather than the sun and gains about three minutes and fifty-six seconds each day. The lst endpoint adds the observer's longitude to give the Local Sidereal Time, LST = GMST + longitude/15 (east positive), which equals the right ascension of any star currently crossing the local meridian. The hour-angle endpoint computes the hour angle of a celestial object, HA = LST − RA, from its right ascension and the local sidereal time (or a date, time and longitude): an hour angle of zero means the object is on the meridian at its highest point, a positive hour angle means it is west of the meridian and setting, and a negative one means it is east and rising. Dates are YYYY-MM-DD and times HH:MM:SS in UT, longitude in degrees and right ascension in hours. Everything is computed locally and deterministically, so it is instant and private. Ideal for astronomy, telescope-control, planetarium, observatory and astrophotography app developers, star-pointing and transit tools, and astronomy education. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is sidereal time; for the sun's position use a solar-position API and for sunrise and sunset times a sunrise API.

api.oanor.com/sidereal-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.oanor.com/solarposition-api

Stellar magnitude and distance maths as an API, computed locally and deterministically. The magnitude endpoint works the distance modulus, m − M = 5·log₁₀(d/pc) − 5 — give any two of the apparent magnitude m, the absolute magnitude M and the distance and it returns the third, with the distance in parsecs, light-years and astronomical units (the absolute magnitude is the apparent magnitude a star would have at 10 parsecs). The flux endpoint applies Pogson's relation to turn a magnitude difference into a brightness ratio, F₁/F₂ = 10^(0.4·(m₂ − m₁)), where five magnitudes is exactly a hundredfold change in brightness — from two magnitudes, a magnitude difference or a ratio. The parallax endpoint converts a parallax angle into a distance, d(pc) = 1 ÷ p(arcseconds), and back, the geometric method behind the parsec itself. Everything is computed locally and deterministically, so it is instant and private. Ideal for astronomy-education, planetarium, stargazing and science app developers, observing and astrophysics tools, and STEM teaching. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is stellar magnitude and distance; for orbital mechanics use an orbital API and for great-circle distances on Earth a geo-distance API.

api.oanor.com/starmagnitude-api

Newtonian gravitation as an API, computed locally and deterministically. The force endpoint applies Newton's law of universal gravitation, F = G·m1·m2/r² — the attractive force between two masses a distance apart, with G = 6.6743×10⁻¹¹ — and solves for whichever of the two masses, the separation or the force you leave out (the Earth and Moon pull on each other with about 2×10²⁰ newtons). The field endpoint gives the gravitational field strength g = G·M/r² at a distance from a mass, or the surface gravity of a built-in body (the Sun, the planets, the Moon and major moons), as a multiple of Earth gravity, and the weight of a test mass placed there. The weight endpoint tells you what something weighs on another world, W = m·g_body — your weight on the Moon, Mars or Jupiter — from a mass or your Earth weight, with the ratio to Earth. Everything is computed locally and deterministically, so it is instant and private. Ideal for physics and astronomy-education tools, space and planetary apps, science museums and games, and engineering. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is gravitational force, field and weight; for orbital speed, period and escape velocity use an orbital-mechanics API.

api.oanor.com/gravitation-api

Optical resolution by the Rayleigh criterion as an API, computed locally and deterministically. The angular endpoint gives the smallest angle two points can be apart and still be told apart through a circular aperture, θ = 1.22·λ/D — the diffraction limit set by the wavelength and the aperture diameter — in radians, degrees, arcminutes and arcseconds (a 100 mm telescope resolves about 1.4 arcseconds in green light), and solves the aperture needed for a target resolution. The distance endpoint turns that angle into a real separation at a distance, s = θ·L = 1.22·λ·L/D — how far apart two objects must be to be resolved at a given range. The microscope endpoint computes resolving power from the numerical aperture: the Rayleigh limit d = 0.61·λ/NA and the Abbe limit d = λ/(2·NA), with NA = n·sin(θ) from a refractive index and half-angle, and the maximum useful magnification. Wavelength defaults to 550 nm (visible) and can be set in metres, nanometres or micrometres. Everything is computed locally and deterministically, so it is instant and private. Ideal for astronomy, telescope and binocular tools, microscopy and imaging-system design, camera and optics apps, and physics education. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is the diffraction-limited resolving power; for thin-lens imaging use a lens API and for slit and grating diffraction use a diffraction API.

api.oanor.com/resolution-api

Orbital-mechanics maths as an API, computed locally and deterministically. The circular endpoint computes a circular orbit around a body — the orbital speed v = √(GM/r), the orbital period T = 2π·√(r³/GM), the escape speed and the specific orbital energy — from a built-in body (Sun, Mercury through Neptune, the Moon) and an altitude above its surface, or from an explicit orbital radius, central mass or standard gravitational parameter. The escape endpoint gives the escape velocity √(2·GM/r) at any radius or altitude, which is √2 times the circular-orbit speed there. The period endpoint applies Kepler's third law in both directions: from a semi-major axis it returns the orbital period, and from a period it returns the semi-major axis — so a sidereal day around Earth gives the geostationary radius of about 42,164 km. Speeds come out in metres and kilometres per second and km/h, distances in metres and kilometres, and periods in seconds, minutes, hours and days. Everything is computed in SI and is instant and private. Ideal for aerospace and satellite tools, space-mission and education apps, astronomy and KSP-style games, and physics calculators. Pure local computation — no key, no third-party service, instant. Live, nothing stored. 3 endpoints. This is orbital mechanics; for live satellite catalogues use a satellites API and for sky positions use an astronomy API.

api.oanor.com/orbital-api

Live near-Earth object close approaches as an API, straight from NASA/JPL's Close-Approach Data (CAD) system. List the asteroids and comets passing nearest Earth over the next N days (or look back), with the approach date, miss distance (in astronomical units, lunar distances and kilometres), relative velocity and an estimated diameter from the object's absolute magnitude; or pull the full close-approach history for a specific object (e.g. 99942 Apophis, 101955 Bennu). Ideal for planetary-defense dashboards, astronomy & space apps, education and "asteroid of the week" content.

api.oanor.com/closeapproach-api

The OpenNGC (NGC/IC) catalogue of deep-sky objects as an API — 13,000+ galaxies, nebulae and star clusters. Look up any object by its catalogue name (NGC224, IC434), Messier number (M31 → Andromeda Galaxy, M42 → Orion Nebula, M1 → Crab Nebula) or common name; browse the full 110-object Messier catalogue; or search by type (galaxy, planetary nebula, globular cluster…) and constellation. Each record carries the object type, J2000 coordinates (sexagesimal + decimal), V/B magnitude, angular size, surface brightness, Hubble morphological type, constellation and cross-catalogue identifiers. Ideal for astronomy apps, telescope planners, planetarium software and education.

api.oanor.com/deepsky-api

The NASA/JPL Small-Body Database (SBDB) as an API — 30,000+ named asteroids and comets with their physical and orbital properties. Look up any minor body by number (e.g. 1 → Ceres), name (Vesta) or SPK-ID; search by name with filters for orbit class, near-Earth (NEO) and potentially-hazardous (PHA) status; or list every near-Earth object. Each record carries the diameter, albedo, absolute magnitude, rotation period and the osculating orbit (semi-major axis, eccentricity, inclination, period) plus the orbit class (main-belt, Apollo, Trojan, …). Ideal for astronomy apps, planetarium software, education and space dashboards.

api.oanor.com/asteroids-api

The CelesTrak satellite catalogue (SATCAT) as an API — 33,000+ catalogued payloads and rocket bodies in (and decayed from) Earth orbit. Look up any object by its NORAD catalogue number (e.g. 25544 → ISS (ZARYA)) or international designator (e.g. 1998-067A); search by name with filters for owner/country, object type and in-orbit status; or list every operator with object counts. Each record carries the operational status, launch date and site, decay status, and orbit (period, inclination, apogee/perigee). Ideal for space dashboards, satellite trackers, OSINT and educational tools. (Catalogued averages, not live ephemeris/TLE.)

api.oanor.com/satellites-api

Explore 6,200+ confirmed planets orbiting other stars, from the NASA Exoplanet Archive. For each exoplanet get its host star, discovery method, year and facility, orbital period, radius and mass (relative to Earth), distance in light-years and equilibrium temperature. Look one up by name, search and filter by discovery method or year, or list every planet in a host system (e.g. TRAPPIST-1). Great for astronomy, education and space apps.

api.oanor.com/exoplanets-api

A catalogue of 9,000+ stars — every named star plus all naked-eye stars to magnitude 6.5 — from the HYG database. Look up a star by name, search and filter by constellation and brightness, list the brightest stars (overall or per constellation), and browse all 88 constellations. Each star includes its constellation, apparent and absolute magnitude, spectral class, distance in light-years and coordinates. Great for astronomy, education and stargazing apps.

api.oanor.com/stars-api

Physical and orbital data for the solar system and beyond: every planet, dwarf planet, major moon and the Sun with NASA fact-sheet values (mass, radius, surface gravity, density, escape velocity, mean temperature, orbital and rotation period, semi-major axis, moon count and rings), plus a searchable catalogue of more than 6,000 confirmed exoplanets from the NASA Exoplanet Archive (radius, mass, orbital period, equilibrium temperature, distance in light-years, host star, discovery year and method). Filter exoplanets by host star, discovery method, year, size or distance, compare solar-system bodies side by side, and look up any single body or exoplanet by name. Every endpoint accepts input via the query string or the request body and returns lean JSON. Pure server-side data (no third-party upstream), so responses are instant and always available. Ideal for education, EdTech, astronomy apps, data visualisation and science tools.

api.oanor.com/planets-api

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.

api.oanor.com/astronomy-api

Track rocket launches from around the world. List upcoming and past launches with launch windows and live status, search by rocket or mission, get full detail for any launch, browse the space agencies behind them, and follow upcoming spaceflight events. Every launch comes as a clean record with the rocket configuration and family, launch service provider, mission name, type, orbit and description, pad and location, weather probability, webcast-live flag and imagery — sourced from The Space Devs’ Launch Library 2. Delivered through a fast, reliable API, ideal for countdown widgets, space-news sites, education tools, calendars and hobbyist apps.

api.oanor.com/spacelaunch-api

Everything about the Moon from one fast, fully-local API. Get the current (or any date) lunar phase with illumination percentage, age in days, phase angle and waxing/waning state, plus the matching emoji; list the upcoming principal phases (new, first quarter, full, last quarter) with accurate UTC timestamps; render a full monthly lunar calendar; and look up the Moon’s zodiac sign and ecliptic longitude. Phase instants are computed with Jean Meeus’ astronomical algorithms and are accurate to about a minute. Every endpoint takes an optional ISO date and works by GET or JSON POST. Pure server-side compute with no third-party upstream, so responses are instant and always available. Ideal for calendar and weather apps, photography and astronomy tools, gardening, fishing and astrology features.

api.oanor.com/moon-api

Latest space news — articles and blog posts about rockets, launches, missions and astronomy, aggregated from dozens of sources (SpaceNews, NASA, ESA, Spaceflight Now and more). Search the archive by keyword or fetch a single article. Great for space dashboards, newsletters, aggregators and education apps.

api.oanor.com/spacenews-api

Search the NASA Image and Video Library — Apollo, Hubble, Mars rovers, the ISS and decades of mission imagery — and fetch the asset file URLs in every resolution for any item. Great for space, education, media, wallpaper and museum apps. All NASA media is public domain.

api.oanor.com/nasa-api

Sunrise, sunset, solar noon, day length and the civil, nautical and astronomical twilight phases for any latitude/longitude and date — plus a multi-day range. Useful for agriculture, solar energy, photography, outdoor scheduling, smart-home automation and astronomy apps.

api.oanor.com/sunrise-api