Focusing the Astrolabe...
▶▼ The ColophonHow the instrument is built, and what it is made of.Enter ChamberLeave Chamber
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The Colophon
━━━━━━━The Observatory projects the real sky above the Sanctuary, computed from the ephemeris for the moment you open it. That is why it stands empty of stars at noon, and why the Moon it shows is the Moon that is actually up.
A zodiac candle is a claim about the heavens, and a house that makes such claims should be willing to show its work. Every vessel in the Zodiac Collection, and everything the Curator writes in the Codex, is written under this sky and can be checked against it.
What it is made of
- The observer
- 3.9°S, 39.6°E, at sea level on the Kenyan coast, keeping East Africa Time. Four degrees south of the equator, where both hemispheres’ skies pass overhead across a year.
- The window
- Due south, across 140° of horizon — the coast’s finest aspect, where Scorpius, Sagittarius, Centaurus, the Southern Cross and the galactic core make their passage.
- The catalogue
- 5,070 stars to magnitude 6 — the naked-eye sky — from HYG v4.1. Of those, 381 carry a full record: proper name, Bayer letter, constellation, spectral class and distance. 89 constellation figures are traced in the Western convention.
- The arithmetic
- Positions, rise and set times, Moon phase and illumination come from astronomy-engine. Each star is then dimmed for its true altitude above the horizon and for how much moonlight is in the air.
The rooms
- The Southern Window — where the projection is drawn. Every named star will give its name.
- The Curator’s Table — the Curator’s answer to what the Window is showing. Observation, then recommendation; the two are never separated.
- The Moon — rendered at its true phase and illumination, and permitted to colour the whole page as it waxes and wanes.