FA-55089 / Astronomical coordinate conventions / Member archive

Stokes linear basis: Feed-ordered Stokes Q loses its signed handedness · case 04

The adapter reports an incorrect linear q while other fields remain valid.

Member previewVariant 4 · 3 implementations · 6 checks per implementation

Case contract

Two real linear-feed correlations XX,YY and real/imaginary XY define stipulated Stokes I=XX+YY,Q=XX-YY,U=2re,V=-2im. Reversing feed labels negates Q and V, leaves I and U unchanged. Output rotated fields model only that feed swap. Output fields are defined by: intensity = d['xx']+d['yy']; linear_q = d['xx']-d['yy']; linear_u = 2*d['re']; circular_v = -2*d['im']; swapped_q = d['yy']-d['xx']; swapped_v = 2*d['im']

Why this case matters

Catalog, detector, sky-coordinate, and spectroscopy adapters must preserve the association between numeric coordinates and their declared reference conventions.

One recorded failure

Sample boundary fixture

This sample comes from the broken implementation of a controlled reproducer.

Boundary fixture	Actual	Expected	Outcome
astronomical fixture 0	`{"circular_v": -8, "intensity": 14, "linear_q": -8, "linear_u": 4, "swapped_q": -8, "swapped_v": 8}`	`{"circular_v": -8, "intensity": 14, "linear_q": 8, "linear_u": 4, "swapped_q": -8, "swapped_v": 8}`	Failed

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This record includes three runnable implementations, regression fixtures, execution results, and source hashes.

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