FA-55263 / Astronomical coordinate conventions / Member archive
Catalog propagated covariance: Catalog propagation omits the two symmetric position-motion covariance terms · case 03
The adapter reports an incorrect position variance while other fields remain valid.
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 fixtureThis sample comes from the broken implementation of a controlled reproducer.
| Boundary fixture | Actual | Expected | Outcome |
|---|---|---|---|
| astronomical fixture 0 | {"acceleration_position_variance": 40.5, "backward_cross_covariance": -5, "motion_variance": 20, "position_motion_covariance": 7, "position_variance": 64.5, "scaled_motion_covariance": 28} | {"acceleration_position_variance": 40.5, "backward_cross_covariance": -5, "motion_variance": 20, "position_motion_covariance": 7, "position_variance": 70.5, "scaled_motion_covariance": 28} | Failed |
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