FA-55513 / Astronomical coordinate conventions / Member archive

Refraction coordinate status: Reference-pressure refraction scaling inverts the pressure ratio · case 03

The adapter reports an incorrect pressure displacement while other fields remain valid.

Member previewVariant 3 · 3 implementations · 6 checks per implementation

Case contract

A supplied refraction displacement r is positive toward zenith. True zenith distance z maps to observed z-r. Apparent altitude equals 90-z+r. Pressure p/p0 scales a reference displacement, and the refraction flag prevents a second application. This model does not compute atmosphere physics. Output fields are defined by: observed_zenith = d['z']-d['r']; observed_altitude = 90-d['z']+d['r']; pressure_displacement = d['r']*d['p']/d['p0']; apply_once = d['z'] if d['already'] else d['z']-d['r']; true_zenith_from_observed = d['z']+d['r']; vacuum_requested = d['z']+d['r'] if d['already'] else d['z']

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	`{"apply_once": 60, "observed_altitude": 30, "observed_zenith": 60, "pressure_displacement": 2.5, "true_zenith_from_observed": 64, "vacuum_requested": 62}`	`{"apply_once": 60, "observed_altitude": 30, "observed_zenith": 60, "pressure_displacement": 1.6, "true_zenith_from_observed": 64, "vacuum_requested": 62}`	Failed

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