A sextant measures the sky and tells you where you stand. Celestial Sextant does the same for your chart: natal charts, transits and synastry computed in your browser from a measured ephemeris — with the evidence behind every sentence.
Free · No account · Your birth data never leaves your device
The instrument
No server round-trips, no account wall, no watered-down "lite" calculator. The same engine runs the free chart and everything else.
Your birth chart with Placidus, Whole Sign or Koch houses, tropical or sidereal — every placement interpreted, with sources.
What's touching your chart today, or any date you choose — with a calendar view of what's coming and when it peaks.
Two charts, read together: cross-aspects, house overlays, and the composite chart of the relationship itself.
Solar returns for your year ahead, and secondary progressions for the slow-moving story underneath.
Classical rulerships, retrogrades, Chiron, the North Node, harmonics and midpoints — the depth the free sites skip.
Keep your charts, note what actually happened, and export a clean PDF report when you want it on paper.
Free vs. Sextant
Free sites earn trust by giving the math away. So do we. You pay for depth, memory and time — never for your own chart.
Free — no account
Sextant — subscription
Accuracy & caveats
"Truncation is chosen, and priced."
Most astrology apps won't tell you how their numbers are made. Ours are computed in your browser from a VSOP87D ephemeris, then checked against the Swiss Ephemeris — the reference standard — and the measured differences are published inside the app, down to the arcsecond.
The app shows its working on every chart: Julian day, sidereal time, timezone resolution, house-system fallbacks, even a state hash you can reproduce. Where a shortcut exists, it is named and its cost is stated.
Pricing
The calculator is free today and stays free. Subscriptions open at launch — join from the app when they do. All prices in USD.
Monthly
$11.11
per month
The full Observatory, month to month. Start with an 11-day trial; cancel in two clicks and keep access until the period ends.
Opens at launchAnnual — save 33%
$88.88
per year
The same Observatory, billed once a year. The right choice if transits and returns are part of your routine.
Opens at launchFounder Lifetime
$111.11
one time · capped
Pay once, keep the Observatory forever. Offered only in the launch window and capped — when it's gone, it's gone.
Launch window onlyWritten reports
$14.95
natal · $19.95 synastry
An authored-quality PDF of your chart — or of a pairing — including the accuracy appendix. No subscription needed.
Opens at launchQuestions
A sextant is the brass instrument sailors used to measure the angle between a star and the horizon — and from that measurement, know exactly where they were. It is honest technology: a number you can check. That is the kind of astrology this is.
Yes — structurally, not just by policy. Your chart is computed in your browser from an ephemeris built into the page. Your birth date, time and place never leave your device, and there is no account to breach.
The engine's positions are checked against the Swiss Ephemeris every release, and the measured residuals are published in the app's Accuracy & caveats panel. Open it and judge for yourself — that page is free forever.
Yes. The whole instrument is a single self-contained page. Once it has loaded, it needs nothing from the internet.
Partly the category — comparable depth costs $9–$15 a month — and partly a quiet wink: 11:11 is the number people make wishes on. The price is in USD because most of the audience is; your card or our checkout handles the conversion.