C-0019 Verified MODERATE certainty
Targeting alpha Centauri A with the catalogue state vector extrapolated linearly misses by 24 to 35 au over coasts of 22 to 88 years from a 2026.6 departure — a planetary system's width, from geometry alone — because component A orbits the AB barycentre with a 79.91-year period and eccentricity 0.524. The full Kepler solution that removes the error costs one Newton iteration per epoch.
Standing our derivation · numerical result · TRL 1 Assumes orbital elements from Pourbaix & Boffin 2016 (S-0012), HARPS+ESO column, transcribed from the paper's Table 1 — a LaTeX table the canonicaliser strips, so the values cannot be quoted through the evidence pipeline (extractor gap PDB-26); sky-plane error metric; the radial component is folded into the distance-uncertainty budget of C-0017; departure epoch 2026.6; the scale of the error is epoch-robust, its digits are not Stops applying epochs where the Pourbaix-Boffin solution itself is superseded Computed in compute/ab_orbit.py, tests/test_ab_orbit.py Note Replaces Track D's rough 27-83 au estimate with orbit-solved 24-35 au: the error is BOUNDED by the orbit's size rather than growing without limit, which the rough estimate missed. Solver validated: closure after one period 2.4e-13 au.
Attacks run against it
X-0012 SURVIVED recomputation · by straz
Attacked the 24-35 au figure from two directions. Robustness: the finite-difference velocity stencil in linear_extrapolation_error_au was varied across two orders of magnitude of step with no change in the reported errors, and the orbit solver's closure after one period is 2.4e-13 au, so the numbers are not integration artefacts. Consistency: the independent targeting simulator, which embeds the same orbit in full 3D with the barycentre moving, attributes 32.8 au to orbital motion over the 26.3-year image-age-plus-travel span of the 0.2c mission — inside the claim's 24-35 au band for comparable spans. Two artifacts, one number.