FA-55320 / Astronomical coordinate conventions / Member archive
Astrometric parallax calibration: Restoring catalog parallax reapplies rather than reverses calibration · case 05
The adapter reports an incorrect uncalibrated roundtrip while other fields remain valid.
Case contract
Stipulated calibration: catalog parallax pi contains additive global zero point z and color slope k*(color-ref). Corrected parallax subtracts both; calibration variances vz and vk are independent. Unknown distances are outside this model. Negative corrected parallaxes remain measurements. Output fields are defined by: corrected_parallax = d['pi']-d['z']-d['k']*(d['color']-d['ref']); zero_point = d['z']+d['k']*(d['color']-d['ref']); calibrated_variance = d['var']+d['vz']+(d['color']-d['ref'])**2*d['vk']; color_sensitivity = -d['k']; zero_point_variance = d['vz']+(d['color']-d['ref'])**2*d['vk']; uncalibrated_roundtrip = d['pi']
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 | {"calibrated_variance": 11, "color_sensitivity": -3, "corrected_parallax": 4, "uncalibrated_roundtrip": -4, "zero_point": 8, "zero_point_variance": 6} | {"calibrated_variance": 11, "color_sensitivity": -3, "corrected_parallax": 4, "uncalibrated_roundtrip": 12, "zero_point": 8, "zero_point_variance": 6} | Failed |
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