What this is
Cygnus is a computational astrology tool. It casts charts, computes house cusps and planetary positions, and runs electional searches — finding moments in time that match conditions you define.
The middle ground between entertainment apps (CoStar, The Pattern) and professional desktop software (Solar Fire, Morinus, Delphic Oracle) is mostly empty on the web. Cygnus builds in that gap — aiming for what you might call the Photoshop or Obsidian of astrology: serious tools, designed carefully, usable by anyone willing to learn.
How it works
Cygnus runs on a custom astronomy engine built on open-source astronomical work — a Rust implementation derived from the Skyfield and jplephem Python libraries, validated to 0.38" mean accuracy against Swiss Ephemeris across a 10-year benchmark of 36,490 positions.
The electional search engine uses continuous root-finding, not hourly sampling — it computes the moments where conditions transition rather than checking every hour and missing windows in between. The condition builder supports recursive AND/OR/NOT trees over 45 templates. Search a year of time in about 280 milliseconds.
Why I built this
A note from the founder.
I'm one person building Cygnus in evenings and weekends, alongside a day job. No external funding, no investors, no roadmap pressure beyond the user feedback that comes in. I'm building in public and releasing as I go.
Open-source acknowledgments
Cygnus's astronomy engine builds on open-source astronomical work:
- Skyfield (Brandon Rhodes, BSD) and jplephem (Brandon Rhodes, MIT) — Python astronomy libraries that informed the Rust implementation.
- JPL DE421 and DE440 ephemerides (NASA JPL, public domain) — the underlying planetary position data.
- IAU and IERS — published specs for precession (Vondrák 2011), nutation (IAU 2000B), and Earth orientation.
- Swiss Ephemeris (Astrodienst) — referenced for accuracy validation only; no code copied.
- Munkasey Astrological Formulary — house system formulas.
Web app credits
- React Router 7 — framework mode with SSR.
- Tailwind CSS 4 — OKLCH color system.
- shadcn/ui — component primitives.
- Umami — self-hosted, cookieless analytics.
- D3 — chart-wheel geometry helpers.
Community and feedback
Cygnus is in early access. The fastest way to shape what it becomes is to use it, then tell us what's broken or missing.
- Email: [TODO contact address]
- Social: [TODO handles]
License and openness
The Cygnus web application and its astronomy engine are works of Cygnus Project LLC (see Terms §10). Your data is yours — see the Privacy Policy for what's stored, who can see it, and how to export or delete it.