FA-54935 / Astronomical coordinate conventions / Member archive

Cube axis slice: Dropping the spectral axis discards celestial cross-coupling · case 05

The adapter reports an incorrect longitude reference while other fields remain valid.

Member previewVariant 5 · 3 implementations · 6 checks per implementation

Case contract

A linear cube has two retained celestial axes and a sliced spectral pixel k with reference rk. Cross-axis CD coefficients ax,ay shift celestial reference values. Spectral world coordinate is rv+dv*(k-rk). Slice thickness is specified in spectral pixels. Output fields are defined by: longitude_reference = d['x']+d['ax']*(d['k']-d['rk']); latitude_reference = d['y']+d['ay']*(d['k']-d['rk']); spectral_coordinate = d['rv']+d['dv']*(d['k']-d['rk']); spectral_width = abs(d['dv'])*d['thick']; lower_edge = d['rv']+d['dv']*(d['k']-d['rk'])-abs(d['dv'])*d['thick']/2; upper_edge = d['rv']+d['dv']*(d['k']-d['rk'])+abs(d['dv'])*d['thick']/2

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	`{"latitude_reference": -4, "longitude_reference": 10, "lower_edge": 128.0, "spectral_coordinate": 132, "spectral_width": 8, "upper_edge": 136.0}`	`{"latitude_reference": -4, "longitude_reference": 26, "lower_edge": 128.0, "spectral_coordinate": 132, "spectral_width": 8, "upper_edge": 136.0}`	Failed

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