FA-55274 / Astronomical coordinate conventions / Member archive

Catalog propagated covariance: Acceleration variance is propagated with the position acceleration coefficient unsquared · case 04

The adapter reports an incorrect acceleration position variance while other fields remain valid.

Member previewVariant 4 · 3 implementations · 6 checks per implementation

Case contract

A catalog supplies position variance p, proper-motion variance m, covariance pm, elapsed interval t, acceleration variance a, and angular scale s. Under the stipulated independent acceleration model position covariance is p+2*t*pm+t*t*m+t**4*a/4. Motion output excludes acceleration unless explicitly requested. Output fields are defined by: position_variance = d['p']+2*d['t']*d['pm']+d['t']**2*d['m']+d['t']**4*d['a']/4; position_motion_covariance = d['pm']+d['t']*d['m']; acceleration_position_variance = d['t']**4*d['a']/4; motion_variance = d['m']+d['t']**2*d['a']; scaled_motion_covariance = (d['pm']+d['t']*d['m'])*d['s']**2; backward_cross_covariance = d['pm']-d['t']*d['m']

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	`{"acceleration_position_variance": 18, "backward_cross_covariance": -5, "motion_variance": 20, "position_motion_covariance": 7, "position_variance": 71.5, "scaled_motion_covariance": 28}`	`{"acceleration_position_variance": 40.5, "backward_cross_covariance": -5, "motion_variance": 20, "position_motion_covariance": 7, "position_variance": 71.5, "scaled_motion_covariance": 28}`	Failed

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This record includes three runnable implementations, regression fixtures, execution results, and source hashes.

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