FA-55800 / Astronomical coordinate conventions / Member archive

Celestial stereographic projection: Stereographic scale metadata reports the inverse magnification · case 05

The adapter reports an incorrect radial scale while other fields remain valid.

Member previewVariant 5 · 3 implementations · 6 checks per implementation

Case contract

A supplied direction e,n,z is mapped by a stipulated stereographic sky chart with scale 2/(1+z), valid z>-1. Reference chart origin ox,oy is added only after projection. Exact antipode has no finite chart coordinate; inputs here have z>=-1. Output fields are defined by: plane_east = 2*d['e']/(1+d['z']) if d['z']>-1 else None; plane_north = 2*d['n']/(1+d['z']) if d['z']>-1 else None; valid = d['z']>-1; translated_east = d['ox']+2*d['e']/(1+d['z']) if d['z']>-1 else None; translated_north = d['oy']+2*d['n']/(1+d['z']) if d['z']>-1 else None; radial_scale = 2/(1+d['z']) if d['z']>-1 else None

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 1	`{"plane_east": 12.0, "plane_north": 6.0, "radial_scale": 0.5, "translated_east": 22.0, "translated_north": 26.0, "valid": true}`	`{"plane_east": 12.0, "plane_north": 6.0, "radial_scale": 2.0, "translated_east": 22.0, "translated_north": 26.0, "valid": true}`	Failed

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