Cycles ArcCycles ArcAstronomy API
The complete sky, one endpoint

Planets, the Moon, eclipses, stars, and meteor showers — computed for your own place and moment.

Send a date, a place, and what you want to know. Get back positions, phases, rise and set times, eclipse circumstances, and what's visible tonight — planet and Moon positions computed on JPL DE441, the same ephemeris professional observatories use, not a low-order approximation.

JPL DE441
planet & Moon positions, observatory-grade ephemeris
8,870 + 88
catalogued stars, deep-sky objects, and every constellation
One call
single GET, JSON back — no desktop app, no data files
Positions are computed from JPL DE441 Chebyshev ephemerides where covered, with an analytic fallback outside the range — and the response tells you which was used. Stars come from the Hipparcos catalog, deep-sky objects from OpenNGC, constellations from the IAU boundaries.
Proof

Real basis, not adjectives

Every claim here traces to a named ephemeris or catalog, not a marketing estimate.

JPL DE441
planet & Moon positions, with analytic fallback labeled in the response
8,870
stars (Hipparcos), plus OpenNGC deep-sky objects
88
constellations with IAU boundaries
One API
positions, phases, eclipses, catalogs, and showers together
CapabilityCycles Arc Astronomy APITypical astronomy API
Planet & Moon positionsJPL DE441 ephemeris, honestly labeledLow-order analytic approximation
EclipsesSolar & lunar, with local circumstances and ground pathOften not offered, or dates only
CatalogsStars, deep-sky objects, and constellations built inFrequently a separate paid product
Meteor showersActive showers, radiant altitude, and Moon interferenceRarely available
Access modelSingle GET call, JSON responseVaries
Every endpoint here is live over HTTP — planet/Moon positions on DE441, eclipses from Besselian elements, the star/DSO/constellation catalogs, sunrise/sunset and twilight, and the meteor-shower module.
Endpoints

Everything this API does

Every endpoint below is live on the API today — same date-and-place in, flat JSON out.

Use cases

Who this is for

Stargazing & weather apps

Tell users what's up tonight, when the Moon rises, and when the next eclipse or meteor shower is visible from where they are.

Planetarium & sky-map apps

Drop-in planet positions and star/DSO/constellation data without shipping your own ephemeris or catalog.

Education & museums

Answer "where is Mars", "what phase is the Moon", "when's the next eclipse" for any place and date, on demand.

Astrophotography planners

Combine visibility, Moon interference, and meteor-shower timing to plan a session around real sky conditions.

Access

Set up one to one

Access is arranged directly, scoped to what you are building. Tell us the volume you expect, the endpoints you need, and the shape of your product — we size the capacity and the terms around it rather than sell you a shelf plan.

What you get

  • Positions, phases, eclipses, catalogs and showers — the whole surface
  • The full DE441 engine: coordinates and time resolved internally
  • Long spans and large catalogs, run in bulk
  • Committed throughput, agreed in the contract rather than metered against you

The forms it takes

  • Evaluation — a key and a window to test against your own reference data
  • Production — committed capacity, SLA, and direct engineering contact
  • Dedicated instance — your own isolated deployment, your region and data residency
  • Research — bulk runs across long spans and large catalogs

How to start

  • Write to enterprise@kairoico.com — every arrangement starts there
  • Send an ephemeris you already trust — we will run it and send back the comparison

Ready to check us against data you trust?

Send one moment and one place. We will run it and send the numbers back beside your reference.

Talk to us
FAQ

Common questions

How accurate are the planet positions?+
Planet and Moon positions come from JPL DE441 Chebyshev ephemerides — the same source professional observatories use — wherever the date falls inside its coverage. Outside that range the API falls back to an analytic model, and every response includes an ephemeris field telling you which was used, so you're never guessing about the basis of a number.
Do you cover eclipses and meteor showers?+
Eclipses, yes — solar and lunar for any year, plus the central-line ground path for a solar eclipse, computed from Besselian elements. Meteor showers too: /v1/meteor/showers lists active showers for a date with peak ZHR, and /v1/meteor/shower adds radiant altitude and Moon interference for your own place and time.
Are the star and deep-sky catalogs included?+
Yes — 8,870 stars from the Hipparcos catalog, deep-sky objects from OpenNGC, and all 88 constellations with IAU boundaries, all searchable by name or by sky position. No separate catalog product to buy.
Is this the same as your astrology API?+
No. This is a straight astronomy API — positions, phases, eclipses, catalogs, and showers, as physics. The astrology API is a separate product with its own site and its own terms.