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chronOSephemeris · engine 4.0.0
chronOSephemeris

precision ephemeris api / release 4.0

Ephemeris precision, proven.

ChronOS is a high-precision astrology API and calculation engine for natal charts, transits, planetary events and auditable celestial data — built for apps, websites and backend systems.

start building freesee the validation
01

exact celestial positions

One UTC instant. One verifiable sky.

Every body includes its position, motion, reference frame, quality and declared precision in a consistent response.

02

validation

Precision is a measurement.

2,050 adversarial epochs against DE440 through an independent ERFA path and against INPOP21a.

03

one calculation core

The same result structure, online or on-device.

Use the hosted astrology API or bring the native engine into an iOS product without changing the calculation model.

04

complete astrology platform

ChronOS 4.0.0

Date-aware sidereal models, fixed-star events, chart calculations and self-service API access in one platform.

create a workspace

Engine identity

engineChronOS 4.0.0
coverage1600–2200
validation2,050 epochs
chart systems14 houses
catalog96 fixed stars
hosted api live native ios available offline-capable core
compressed radius scale · concentric orbits
01

validated against independent astronomical references

Precision you can inspect, test and trust.

ChronOS publishes conservative error budgets and validates its results against independent astronomical references — including difficult segment boundaries, stations and house cusps.

moon · max against INPOP21a0.54″

Maximum observed lunar difference against the independent INPOP21a reference. This is an internal validation run against an independent reference, not an external certification. The separate DE440/ERFA comparison measured 0.45″.

body / referencemeasuredbudget
Sun · DE440 max0.20″5″
Moon · DE4400.45″2″
Moon · INPOP21a0.54″2″
Mercury–Saturn · max≤ 2.45″10″

Bars show the consumed share of the conservative error budget.

2,050adversarial epochs
< 0.5″ramc / asc with dut1
< 1 µasgast against pyerfa
≤ 2″fixed stars vs. Swiss

reproducible astronomy

Position, time, and orientation models are reproducibly tested.

VSOP87, the Chebyshev Moon, IAU 2006/2000A, ERA-based GAST, and embedded EOP data form one continuous computational chain.

traceable scientific sources

Every model names the data and standards behind it.

VSOP87/IMCCE, JPL, IERS, ERFA and Hipparcos remain explicitly attributed so teams can understand exactly how each result was produced.

02

deployment options for astrology software

Precision travels with your product.

Use ChronOS through the hosted API or a compatible native runtime. Quality states remain explicit so applications can respond clearly when calculation paths change.

1precision

native ios

On-device

Run the verified Rust engine offline inside compatible iOS products.

2precision

https api

ChronOS API

Call the same calculation core from web products, services and mobile backends.

3analytic

declared fallback

Graceful continuity

If a product uses an analytic fallback, the quality change remains visible instead of being hidden.

version-safe native calculations

Matched engine, data and contract — or a safe API route.

Native integrations verify engine version, dataset identity and response contract before accepting a precision result.

engine === dataset === sha === contract

developer api

An interface that carries its provenance.

Every exact response includes epoch, frame, engine, dataset SHA, algorithm, coverage, and quality state.

01/ephemeris/instant

Exact UTC instant with the complete engine metadata envelope

02/ephemeris/instant/extended

Uranus through Vesta in the shared v3 contract

03/stations

Station times found through root-finding with sub-minute resolution

04/fixed-stars

96 fixed stars, including 15 Behenian stars; positions and typed event search

05/v2/charts/calculate

Typed chart families, 14 house systems, and historical time zones

06/v2/lunar-sectors/calculate

Nakshatras, padas, named date-aware ayanamshas, and explicit conventions

07/sun · moon · horizon

Established surfaces for light, phase, and the local horizon

03

from position to meaning

Exact coordinates become a language of time.

The ephemeris establishes the measurable state. Tradition-specific layers then transform that state into planetary hours, decans, lunar mansions, and transparent combination texts.

AOM concentric planetary clockTwenty-four planetary hours surrounded by decans, zodiac signs, lunar mansions, and dedicated Sun and Moon orbit lanes.12345678910111213141516171819202122232425262728
AOM planetary clockMonday · Moon24 hours · 36 decans · 28 mansions
01 exact instant02 tradition model03 combination rules04 attributed language
04

astrology software infrastructure

One precise engine for the complete astrological workflow.

Build natal charts, transit timelines, electional tools, lunar calendars and live sky experiences on one consistent source of celestial data. Every model stays explicit, versioned and ready for product use.

The machine registry currently enumerates 28 bodies and points, 14 house systems, 4 named ayanamshas, and 26 event query types. Inspect chronos-capabilities-2026.07.16.

calculation becomes interface

Chart-ready data, not just coordinates.

ChronOS returns structured bodies, houses, aspects, motion and timing events that can move directly into natal charts, transit views, calendars and custom product experiences.

SaturnJupiterMarsSunVenusMercuryMoon
Illustrative natal chart generated with ChronOSA compact chart wheel with houses, planetary positions, and example aspects.
Illustrative radixhouses · bodies · aspects
available integration ready available with disclosed limits
A

Charts & time navigation

6 capabilities

Natal and current charts

available

Exact radix and chart-for-now snapshots with 14 house systems, configurable aspects, motion and traditional state.

/v2/charts/calculate · /v2/render

Transits and timelines

available

Double-wheel data, personal transits, orb entry, exact contact, exit, retrograde contact sequences and chronological normalization.

/v2/timeline · aspect_contacts

Synastry and composite

available

Cross-chart aspects, midpoint composite and Davison charts are first-class typed calculations rather than UI approximations.

synastry · composite · davison

Progressions and directions

available

Secondary progressions plus true solar arc and Naibod axes in longitude or right ascension; solar arc and primary directions remain separate techniques.

4 axis methods · deterministic basis

Returns and revolutions

available

Solar, lunar and planetary returns use resolved roots. Annual revolutions expose the exact returned instant and chart.

≤ 0.5 s numerical bracket

Profiles and saved configurations

integration ready

Versioned calculation profiles keep house systems, aspect rules and coordinate options consistent across every project and environment.

versioned profiles · repeatable results
B

Event explorer & daily sky

6 capabilities

Event search

available

Ingresses, stations, aspects, phases, eclipses, seasons, elongations, occultations, horizon events and custom time windows in one query.

/v2/events/search

Global and personal timelines

available

Astronomical, astrological, planetary-hour, natal-transit and custom-trigger records share one sortable contract.

/v2/timeline

Retrogrades and stations

available

Stationary windows, exact direction changes, speed extrema and renderable retrograde calendars are available directly.

station · speed_extremum · calendar

Moon, VoC and eclipses

available

Eight phases, exact principal phase events, void-of-course intervals and physical eclipse geometry extend beyond a basic lunar calendar.

moon_phase · void_of_course · eclipse

Planetary hours and days

available

Location-aware unequal hours, twilight, day rulers and dedicated wheel rendering with webhook-ready transitions.

DST + polar behavior tested

Digests, widgets and alerts

integration ready

Stable event IDs, webhooks and live streams supply the data layer for daily digests, notifications, widgets and in-app sky updates.

webhook · SSE · WebSocket
C

Lunar, stellar & minor-body layers

6 capabilities

Nakshatras and padas

available

The 27-fold sidereal division, four padas and boundary events support date-aware Fagan/Bradley, Lahiri, Raman and Krishnamurti references — plus explicit fixed offsets.

/v2/lunar-sectors/calculate · named ayanamshas

Arabic lunar mansions

available

A clearly named equal-28 tropical convention is available. ChronOS does not mislabel it as a universal reconstruction of historical stellar boundaries.

arabic_mansions_28_equal

Fixed stars

available

A curated proper-motion catalog and 15 Behenian stars feed apparent positions, exact/custom aspects, orb contacts, rise, set and both culminations.

96 stars · ≤2″ validation · typed events

Nodes and sensitive points

available

Mean and osculating true nodes, south nodes, Lilith variants, Earth shadow, antisolar and seasonal points are canonical body keys.

28 standard body/point keys

Asteroids and custom objects

available with limits

Chiron, Ceres, Pallas, Juno and Vesta are available as named bodies. Additional objects can be calculated through bounded custom orbits with an explicit error budget.

limited named catalogue · custom orbits

Transparent tradition models

available with limits

Every tradition-specific calculation names its convention and reference. ChronOS never presents an equal division as a historical stellar boundary.

explicit model and limitation disclosure
D

Views, automation & sovereignty

6 capabilities

Heliocentric solar system

available

Heliocentric positions and a deterministic solar-system scene are available beside geocentric and topocentric frames.

heliocentric · solar_system_view

Visual studio

available

Wheels, aspect and declination graphs, calendars, local-space radar, astrocartography and timeline scenes render to SVG, PNG, PDF or JSON.

17 visual families

Electional search

available

Rule-based electional windows combine events, dignities, houses, planetary hours, VoC and exclusions with inspectable scoring evidence.

/v2/electional/search

Offline-ready runtime

integration ready

The Rust core and native iOS interface can calculate without a network while preserving the same result structure used by the hosted API.

local native · shared contract

API and SDK surface

available

REST, batch, realtime, webhooks, CLI, MCP and generated SDK targets expose the same normalized engine facts to products and agents.

OpenAPI · result hashes · provenance

Strict-facts AI context

available

Schema-bounded facts keep calculation separate from authored interpretation, with source and uncertainty visible to downstream models.

/v2/ai/context
05

astrology api for developers

From one exact instant to product-ready celestial data.

These compact patterns show the shape of a ChronOS integration without exposing production credentials or pretending that one snippet fits every plan. Your dashboard provides runnable examples, live keys and the complete response schema available to your subscription.

01 · request patternillustrative
chronos.calculate({  instant: "UTC timestamp",  profile: "your profile",  bodies: ["sun", "moon", "…"]})
02 · verified resultabridged
result: {  positions: [ longitude, latitude ],  motion: "direct | retrograde",  precision: "declared",  provenance: "included"}
03 · product outputplan-dependent
chart: {  houses: [ "…" ],  aspects: [ "…" ],  timeline: [ "…" ],  render: "SVG | PNG | PDF"}

Pattern preview only. Copy-ready cURL, TypeScript and response examples appear inside your workspace and match the capabilities of your active plan.

06

transparent api pricing

Start free. Scale when your astrology product grows.

Choose a monthly plan in euros and move up whenever you need more requests, projects, chart families or realtime features. Applicable taxes are shown during checkout.

free
€0forever

Evaluate the contract and ship a small prototype.

  • 2,500 requests / month
  • One project · two keys
  • Natal charts
  • Default radix SVG
developerbest for first product
€24per month

Build a focused astrology feature or integration.

  • 25,000 requests / month
  • Two projects · five keys
  • Natal, transit + synastry
  • Three webhooks
studio
€79per month

Run a complete astrology product and visual workflow.

  • 150,000 requests / month
  • All chart families
  • All render formats
  • Batch, electional + AI facts
scale
€199per month

Operate high-volume products with live celestial state.

  • 3M requests / month
  • 25 projects · 100 keys
  • Realtime SSE / WebSocket
  • Extended analytics

Every plan begins with a private dashboard, usage visibility and secure key management. Paid self-service remains in controlled launch until the published operational and legal gates are complete.

08

reliable astrology api infrastructure

Accuracy continues beyond the algorithm.

Versioned datasets, reproducible builds, runtime parity and continuous health checks turn precise calculations into a dependable product service.

01

Versioned calculations

Engine, datasets and contracts carry explicit versions so results remain reproducible over time.

02

Verified source data

Scientific inputs are archived with checksums and provenance before they enter the calculation pipeline.

03

Native and API parity

Shared fixtures verify that compatible runtimes produce the same normalized celestial state.

04

Protected access

Project keys, scopes and usage limits keep customer integrations isolated and manageable.

05

Continuous data health

Coverage and freshness checks protect time-sensitive Earth-orientation and reference datasets.

09

knowledge base

Understand the calculation, not just the response.

Technical guides explain the time systems, coordinate choices and model boundaries behind the API. Each page pairs the method with a runnable request and evidence requirements.

Astronomical computationEphemeris calculations for auditable celestial software

Learn how an astronomical ephemeris converts an exact instant into planetary positions, motion and versioned calculation metadata.

Developer APIEphemeris API for planetary positions and celestial events

Integrate planetary positions, charts and celestial event calculations through the versioned ChronOS Ephemeris API.

Methods and modelsAstronomical calculations: from civil time to celestial coordinates

A practical overview of time scales, reference frames and numerical models used to calculate celestial positions and events.

Planetary dataPlanetary positions API with motion and provenance

Calculate planetary longitude, latitude, distance and motion for an exact UTC instant through the ChronOS API.

Time systemsJulian Day conversion for astronomical calculations

Convert UTC, calendar dates and Julian Day values across astronomical time scales with explicit calendar conventions.

Lunar calculationsMoon phase API for lunar state and event timelines

Calculate the Moon’s phase state and search lunar phase events with explicit astronomical definitions.

Chart geometryAstrological house systems as explicit calculation models

Understand how astrological house cusps are calculated and why the selected house system, location and fallback behavior must be explicit.

Reference systemsSidereal astrology API with named ayanamsha models

Calculate sidereal positions and lunar sectors with an explicit, date-aware ayanamsha or documented reference offset.