FA-55678 / Astronomical coordinate conventions / Member archive

Spectral channel edges: Spectral window extent excludes the outer half-channel supports · case 03

The adapter reports an incorrect window extent while other fields remain valid.

Member previewVariant 3 · 3 implementations · 6 checks per implementation

Case contract

A spectral window has first center c0, signed center step d, integer channel i starting at zero, full width w>0, channel averaging factor b, and total n channels. Edges are always ascending world-coordinate values; averaging preserves the mean of contributing channel centers. Output fields are defined by: center = d['c0']+d['i']*d['d']; edges = [d['c0']+d['i']*d['d']-d['w']/2,d['c0']+d['i']*d['d']+d['w']/2]; averaged_center = d['c0']+(d['i']*d['b']+(d['b']-1)/2)*d['d']; averaged_step = d['b']*d['d']; window_center = d['c0']+(d['n']-1)*d['d']/2; window_extent = abs((d['n']-1)*d['d'])+d['w']

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	`{"averaged_center": 120.0, "averaged_step": 8, "center": 110, "edges": [108.5, 111.5], "window_center": 116.0, "window_extent": 32}`	`{"averaged_center": 120.0, "averaged_step": 8, "center": 110, "edges": [108.5, 111.5], "window_center": 116.0, "window_extent": 31}`	Failed

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