FA-55893 / Astronomical coordinate conventions / Member archive

Nested sky cell address: Nested sky face offset uses order rather than pixels per face · case 03

The adapter reports an incorrect global pixel while other fields remain valid.

Member previewVariant 3 · 3 implementations · 6 checks per implementation

Case contract

A stipulated hierarchical sky tessellation has 12 base faces and four nested children per cell. At order o a face has 4**o pixels. p is the local pixel index, f the face, k the child digit. Parent and descendant ranges are nested indexing operations; no geometric HEALPix projection is implemented. Output fields are defined by: global_pixel = d['f']*4**d['o']+d['p']; parent_local = d['p']//4; child_local = 4*d['p']+d['k']; descendant_first = d['p']*4**d['depth']; descendant_stop = (d['p']+1)*4**d['depth']; face_count = 12*4**d['o']

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	`{"child_local": 30, "descendant_first": 112, "descendant_stop": 128, "face_count": 192, "global_pixel": 13, "parent_local": 1}`	`{"child_local": 30, "descendant_first": 112, "descendant_stop": 128, "face_count": 192, "global_pixel": 55, "parent_local": 1}`	Failed

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