FA-55357 / Astronomical coordinate conventions / Member archive

Ephemeris hermite state: Ephemeris derivative is left in normalized interval units · case 02

The adapter reports an incorrect midpoint velocity while other fields remain valid.

Member previewVariant 2 · 3 implementations · 6 checks per implementation

Case contract

A bounded one-axis ephemeris interval provides endpoint positions p0,p1 and velocities v0,v1 across duration h. At midpoint, cubic Hermite value and derivative use time-scaled tangents. Also expose normalized endpoint tangents and acceleration endpoints as diagnostics. h is positive. Output fields are defined by: midpoint_position = (d['p0']+d['p1'])/2+d['h']*(d['v0']-d['v1'])/8; midpoint_velocity = 1.5*(d['p1']-d['p0'])/d['h']-(d['v0']+d['v1'])/4; left_tangent = d['h']*d['v0']; right_tangent = d['h']*d['v1']; left_acceleration = 6*(d['p1']-d['p0'])/d['h']**2-(4*d['v0']+2*d['v1'])/d['h']; right_acceleration = -6*(d['p1']-d['p0'])/d['h']**2+(2*d['v0']+4*d['v1'])/d['h']

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	`{"left_acceleration": 0.625, "left_tangent": 8, "midpoint_position": 10.5, "midpoint_velocity": 20.5, "right_acceleration": 1.375, "right_tangent": 24}`	`{"left_acceleration": 0.625, "left_tangent": 8, "midpoint_position": 10.5, "midpoint_velocity": 3.625, "right_acceleration": 1.375, "right_tangent": 24}`	Failed

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

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