Caelus
Clean-room astrology computation monorepo. MIT, no Swiss Ephemeris code, no AGPL, no ephemeris files. Caelus computes ephemeris positions, charts, events, hellenistic timing techniques, Vedic methods, citable chart facts, sky-view image-prompt frames, and the MCP tools around them. Live at ephemengine.com.
Packages
| Path | npm | Description |
|---|---|---|
packages/caelus | caelus | TypeScript engine (~151 KB gzipped total, zero deps) |
packages/caelus-mcp | caelus-mcp | MCP server: charts, transits, synastry, events, eclipses |
packages/caelus-delineations-pd | — | Public-domain interpretation corpus + default validation set for interpret() |
packages/birth | caelus-birth | Birth time + place → UT (timezone and DST resolution) |
packages/wheel | caelus-wheel | React SVG chart wheel, zero runtime deps |
apps/web | — | Next.js site: playground, validation, edge /api/chart |
caelus-starter | — | Next.js starter app (separate repo) |
The Python reference engine and data-fitting pipeline live in python/;
they mint the coefficient data and golden fixtures and are not a runtime
dependency.
Docs
- ARCHITECTURE.md — layout, durability decisions, product strategy
- MCP_SPEC.md — MCP tool contract
- docs/gap-analysis.md — Swiss Ephemeris comparison (closed at 0.5.0)
- docs/agents.md — pitfalls for coding agents building on Caelus
- docs/releasing.md — release process
Quick start
npm install
npm run build
npm test
npm run dev -w web
http://localhost:3000 — live chart in the browser.
Edge API: GET /api/chart?date=…&lat=…&lon=….
Branches
main— stable releasesdev— active development