# Historical drilling geographic alignment


## Version0009 — approximate geographic historical drilling

The combined top view now covers ULG and Paleo East, roughly 11km apart, with Both targets / ULG / Historical drilling presets. June collar symbols and interval cards use the printed 505000E / 7550000N grid and 1km scale, assuming WGS84 / UTM33S. No empirical shift was applied. An optional draped June-map overlay retains its original crop geometry.

Independent Sentinel comparison: 14 of17 spatially withheld feature matches agree with a diagnostic similarity fit within3 source pixels; three false matches remain recorded. The full withheld grid-placement median residual is58m; the consistent subset maximum is73m. The diagnostic correction was not applied. These are image-matching results, not surveyed accuracy. Source digitisation ±3px is about42m; datum and original-map systematic errors are unquantified. VB05/VB06 remain a pair; RC27/RC28 remain unlocated; no underground trajectory is inferred.

Controls, all residuals and rejected descriptor matches: [registration.json](../derived/geographic-v9/registration.json). Grid equations: E=505000+(x−417)×1000/72; N=7550000+(309−y)×1000/72. Original image dimensions594×449.

Competing interpretations: a 1.1% scale and small translation correction fits imagery more closely, plausibly reflecting low-resolution scale reading. It is recorded but not applied because its geodetic meaning is unverified. Assuming a different datum remains an unresolved alternative.

## Before / after and verification

Before: historical drilling appeared only in a separate source-local panel. After: three recovered symbols occupy their approximate geographic positions in the same terrain scene as ULG, with original source coordinates retained. RC08 lies11.135km from the ULG focus point. Both targets, close-focus presets, interval selection, layer controls and saved overlay state were checked in the browser. Desktop and390px mobile screenshots were reviewed. Source records, original scenes, reported intervals and market calculations remain unchanged.