FA-55229 / Astronomical coordinate conventions / Member archive
Sidereal hour angle adapter: Meridian target conversion back to catalog RA applies the apparent correction twice · case 04
The adapter reports an incorrect meridian ra while other fields remain valid.
Case contract
All angular values are exact model degrees. East longitude is positive. Local mean sidereal angle is gmst+lon, apparent sidereal includes eqeq, apparent RA is ra+dra. Hour angle is sidereal minus RA, normalized into [0,360). No Earth rotation is calculated. Output fields are defined by: local_mean = (d['gmst']+d['lon'])%360; local_apparent = (d['gmst']+d['lon']+d['eqeq'])%360; apparent_ra = (d['ra']+d['dra'])%360; mean_hour_angle = (d['gmst']+d['lon']-d['ra'])%360; apparent_hour_angle = (d['gmst']+d['lon']+d['eqeq']-d['ra']-d['dra'])%360; meridian_ra = (d['gmst']+d['lon']+d['eqeq']-d['dra'])%360
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 | {"apparent_hour_angle": 82, "apparent_ra": 53, "local_apparent": 135, "local_mean": 133, "mean_hour_angle": 83, "meridian_ra": 138} | {"apparent_hour_angle": 82, "apparent_ra": 53, "local_apparent": 135, "local_mean": 133, "mean_hour_angle": 83, "meridian_ra": 132} | Failed |
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