Precision without false certainty.
We separate calculation, source evidence, editorial meaning, location enrichment, weather, and official geographic boundaries.
What appears first
Every event presents the moment, why it matters, an on-site indoor experience, optional local meaning, outside detail, evidence, and outcome—in that order. An event cannot publish without its indoor layer.
Calculation
Clockwork timestamps use astronomy-engine@2.1.19, pinned under its MIT license and checked against USNO/NASA reference cases. UTC civil timestamps; Astronomy Engine approximates UT1 and UTC as equivalent and models TT internally. normal atmospheric refraction only where Astronomy Engine applies it; weather is outside the calculation.
Visibility labels
Easy to spot requires a usable window, at least 20° calculated altitude, civil-dark sky, appropriate brightness, and a non-boundary region. Otherwise naked-eye opportunities become Possible with a clear view. Binocular and telescope expectations always take precedence over optimistic altitude. A horizon crossing alone is never “easy.”
Eclipses and boundaries
regional boundaries are never inferred from a point calculation; the official map and boundary buffer control. The exact official map controls; rounded coordinates are not used to promise totality near a path edge. Solar safety text is versioned from NASA and cannot be freely generated.
Location and privacy
No location is required. City search uses an offline GeoNames cities15000 artifact under CC BY 4.0 and IANA timezone identifiers. Browser coordinates are optional and rounded to 0.1° before they can be saved. Analytics rejects city names, coordinates, email, and feed or management tokens. Remove-location, feed rotation, and full profile deletion are first-class controls.
Live and forecast state
Official live experiences move through live → ended/replay → on-site fallback. A broken player never removes the event’s useful explanation. Forecast lanes disappear when stale and never empty the clockwork week.
Corrections and rights
Source revisions are append-only. A corrected time raises the event/calendar sequence and supersedes reminders. Media appears only with asset-level source, exact credit, rights evidence, hash, representation label, transformation, alt text or transcript, and fallback.