**Bead document** from Bead: Fire Progression · [canonical source](https://redfish.acequia.io/guerin/.agents/182bd1a7-a376-4dd0-b445-578adc6635b9/bead-bind-startup.md) · discussion: Talk: Fire Progression
**Do this first:** read [about.md](about.md), then `2026-06-16/notes/00-toa-raster-from-perimeters.md`. **Current focus:** spec for perimeter→TOA-raster interpolation, grounded in the Sandy Fire. The reported ignition origin and full narrative were imported 2026-06-16. **Onboarding index:** - Algorithm spec → `2026-06-16/notes/00-toa-raster-from-perimeters.md` - Worked example (origin, STAC mount, t0 discrepancy) → `2026-06-16/notes/01-sandy-fire-worked-example.md` - Imported narrative → `2026-06-16/artifacts/sandy-fire-narrative.md` - Mounted data → `names.json` (`sandy-stac` → `cbf8b027` Sandy Fire STAC) **Open next actions:** - Decide whether to recompute the TOA from the true ignition origin (34.25235, -118.746484) vs the existing centroid-derived origin in `toa-2026_CAVNC_042326_sandy.json`. - Reconcile the reported ignition time (~17:17 Z) with the existing TOA `start_datetime` (23:49 Z).