FA-55353 / Astronomical coordinate conventions / Member archive

Ephemeris hermite state: Ephemeris midpoint interpolation drops time-scaled endpoint velocity information · case 03

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

Member previewVariant 3 · 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": 0.25, "left_tangent": 8, "midpoint_position": 13.0, "midpoint_velocity": 3.25, "right_acceleration": 1.75, "right_tangent": 24}`	`{"left_acceleration": 0.25, "left_tangent": 8, "midpoint_position": 11.0, "midpoint_velocity": 3.25, "right_acceleration": 1.75, "right_tangent": 24}`	Failed

MEMBER ARCHIVE

The complete case is available to members.

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

Member access is invitation-based. Sign in with your invited account to inspect the sources.