FA-55939 / Astronomical coordinate conventions / Member archive

Multiorder sky cell encoding: Sky probability density is exported as cell probability without area conversion · case 04

The adapter reports an incorrect cell mass while other fields remain valid.

Member previewVariant 4 · 3 implementations · 6 checks per implementation

Case contract

A bounded multiorder sky cell uses uniq=4*4**order+pixel, where pixel is the global nested pixel index with 0<=pixel<12*4**order. Coarsening one level preserves face by integer division of pixel by four. Cell area is normalized to whole-sky area one. Output fields are defined by: uniq = 4*4**d['order']+d['pixel']; band_start = 4*4**d['order']; cell_area = 1/(12*4**d['order']); cell_mass = d['density']/(12*4**d['order']); child_uniq = 4*4**(d['order']+1)+4*d['pixel']+d['sub']; order_stop = 16*4**d['order']

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	`{"band_start": 64, "cell_area": 0.005208333333333333, "cell_mass": 8, "child_uniq": 338, "order_stop": 256, "uniq": 84}`	`{"band_start": 64, "cell_area": 0.005208333333333333, "cell_mass": 0.041666666666666664, "child_uniq": 338, "order_stop": 256, "uniq": 84}`	Failed

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