FA-55684 / Astronomical coordinate conventions / Member archive

Exposure time coordinate: Exposure reference fraction is ignored in favor of midpoint convention · case 04

The adapter reports an incorrect reference time while other fields remain valid.

Member previewVariant 4 · 3 implementations · 6 checks per implementation

Case contract

A detector exposure starts at t with integration duration e. Row y has rolling delay y*r; shutter traversal adds y*s. A barycentric timestamp offset b is supplied in the same model ticks. FITS-like fractional exposure reference f selects start f=0, midpoint f=0.5, or end f=1. Output fields are defined by: reference_time = d['t']+d['f']*d['e']; row_start = d['t']+d['y']*d['r']; row_midpoint = d['t']+d['y']*d['r']+d['e']/2; shutter_corrected = d['t']+d['f']*d['e']+d['y']*d['s']; barycentric_midpoint = d['t']+d['e']/2+d['b']; end_time = d['t']+d['y']*d['r']+d['e']

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 1	`{"barycentric_midpoint": 112.0, "end_time": 119, "reference_time": 108.0, "row_midpoint": 114.0, "row_start": 109, "shutter_corrected": 106}`	`{"barycentric_midpoint": 112.0, "end_time": 119, "reference_time": 103, "row_midpoint": 114.0, "row_start": 109, "shutter_corrected": 106}`	Failed

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