FA-54879 / Astronomical coordinate conventions / Member archive

Binned detector centers: Anisotropic binning applies the other detector axis geometry · case 04

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

Member previewVariant 4 · 3 implementations · 6 checks per implementation

Case contract

Pixel centers are one-based. A bin of bx by by starts at zero-based crop sx,sy. Its first center is start+(bin+1)/2. The supplied dispersion and plate scales are per unbinned pixel; bin integral weights count physical contributing pixels. Output fields are defined by: reference_x = (d['rx']-d['sx']-(d['bx']+1)/2)/d['bx']+1; reference_y = (d['ry']-d['sy']-(d['by']+1)/2)/d['by']+1; plate_scale = d['scale']*d['bx']; spectral_step = d['disp']*d['by']; footprint_pixels = d['bx']*d['by']; last_center_x = d['sx']+(d['bx']+1)/2+(d['nx']-1)*d['bx']

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	`{"footprint_pixels": 8, "last_center_x": 25.5, "plate_scale": 6, "reference_x": 7.25, "reference_y": 5.125, "spectral_step": 20}`	`{"footprint_pixels": 8, "last_center_x": 25.5, "plate_scale": 6, "reference_x": 7.25, "reference_y": 4.875, "spectral_step": 20}`	Failed

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