Physical Heliacal Visibility Phase 1 Closure

Date: 2026-07-30

Status: Phase 1 complete; Phase 2 is the next authorized phase

Runtime boundary: separately validated data pack exists, but no engine loader, public API, release, or deployment is part of this phase

Governing plan: PHYSICAL_HELIACAL_VISIBILITY_IMPLEMENTATION_PLAN.md

Radiance evidence: PHYSICAL_HELIACAL_VISIBILITY_PHASE1_RADIANCE_RESPONSE_CHECKPOINT_2026-07-30.md

Compact closure receipt: tests/artifacts/visibility_reference_lab/phase1_closure_checkpoint_2026-07-30.json

Closure-receipt SHA-256: 6daaa62566214747dd50bc449da577065a2484c707ec39b7c1d88dafb0778776

Outcome

Phase 1 now has a reproducible offline atmospheric reference laboratory and a separate immutable physical-visibility data pack. All admitted reference artifacts and the final pack passed independent validation on Linux and Windows. The pack is not installed into Moira and cannot be acquired automatically.

The phase closes with:

• checksum-bound libRadtran 2.0.6 and REPTRAN 2024 source identities;
• named-atmosphere, environmental-role, aerosol, ozone, pressure, albedo, and direct-versus-radiance contracts;
• admitted observer-altitude and pressure-ratio direct-extinction interpolation evidence;
• adaptive response-integrated directional-radiance tables;
• untouched response and direct-extinction holdouts;
• separate solver, interpolation, and storage-error bounds;
• a versioned metadata-only compatibility contract;
• an exact-inventory, caller-path-only independent pack validator; and
• durable admitted and rejected-design receipts.

Final Data Pack Identity

Field	Value
Pack ID	moira-physical-heliacal-visibility
Version	1.0.0
Compatibility ID	moira-physical-heliacal-visibility-data-pack-v1
Format	regular-grid-ieee754-binary32-le-v1
License	CC BY-SA 4.0
External directory	moira-physical-heliacal-visibility-1.0.0-v2
Files	12
Bytes	110,481
Payload files	11
Generation fingerprint	b0d09b91086c2b3064e6c56cfaeae97226e7a6b2779fd70c5b7807aeab748750
Manifest SHA-256	49ac2b68ea105a8e055b27e8d4d70f6cbfe9533f971ef5e6000f0bdd95d6771b
Source-artifact manifest SHA-256	6bb91212d1d54762af8276ea066b4c6d5f4df837d84a46057f57b35924bae12f
Linux validation	Passed
Windows validation	Passed

The pack contains four 64-cell response products—photopic luminance, scotopic luminance, and their per-cell relative standard errors—plus 22,800 direct-extinction values, axes, the admitted error envelope, provenance, checksums, README, and licensing notice.

It contains no CIE source table, libRadtran or REPTRAN source/data file, profile, executable, or engine code.

First-Pack Domain

The first pack is deliberately a fixed-environment baseline:

Input	Admitted value or interval
Molecular atmosphere	U.S. Standard
Aerosol profile	rural summer
Observer altitude	0 m
Surface pressure	1013.25 hPa
AOD550	0.1
Angstrom exponent	1.3
Ozone	300 DU
Gray ground albedo	0.2
Solar-center altitude	-9 to 0 degrees
Target true altitude	0.25 to 45 degrees
Relative solar azimuth	0 to 180 degrees

The earlier Phase 1 environmental and altitude/pressure studies establish source semantics and bounded evidence; they do not silently add those environmental dimensions to this first pack. Phase 2 must return typed not_evaluable outside the manifest's exact domain. A broader atmosphere, altitude, pressure, aerosol, ozone, or albedo domain requires a new versioned data pack and independent evidence.

This distinction prevents a flexible request contract from being mistaken for data that the first pack does not actually contain.

Interpolation and Error Contract

Response luminance uses trilinear interpolation in log10 luminance over solar altitude, target altitude, and relative solar azimuth. Direct extinction uses linear interpolation in extinction magnitude over log10(target_true_altitude_deg + 0.25) independently in each one-nanometre spectral bin. Neither path extrapolates.

Error owner	Admitted Phase 1 evidence
Photopic response interpolation	maximum 0.354270 mag; p95 0.287715 mag
Scotopic response interpolation	maximum 0.252966 mag; p95 0.244817 mag
Direct-extinction interpolation	maximum 0.0212954 mag; p95 0.00279149 mag
Binary32 storage	maximum 9.487461198887104e-7 mag
Solver uncertainty	retained per response cell
Limiting-magnitude propagation	Phase 2 owner
Event-time propagation	Phase 3 owner

The 531 nm monochromatic reconstruction remains a transparent diagnostic only. It is not shipped or used as a runtime interpolation surface.

Modeled twilight below -9 degrees solar-center altitude is typed not_evaluable with reason solar_twilight_below_data_pack_domain; a Monte Carlo zero is never treated as physical zero.

Validator and Failure Law

The independent validator accepts only an explicit caller-supplied directory. It enforces:

• supported pack and format versions;
• exact file inventory and regular-file status;
• no symlinks or unexpected directories;
• manifest, payload, and SHA256SUMS identities;
• finite positive table values and exact axis/value counts;
• compatibility, interpolation, error-envelope, license, and provenance contracts; and
• zero network access.

Missing, corrupt, unsupported, or out-of-domain data fails explicitly. No code path searches for or downloads a replacement.

The first compiled 1.0.0 candidate was rejected because two required notice phrases were split by Markdown wrapping. Its numerical tables, checksums, and provenance passed, but the artifact was not admitted. The rejected directory remains immutable and is bound by phase1_visibility_data_pack_v1_failed_notice_checkpoint_2026-07-30.json. The admitted v2 rebuild changes the notice packaging and tooling receipts, not the scientific source artifact.

Phase 1 Exit Gate

• Source, generator, configuration, and external-data identities are checksum bound.
• The documented external laboratory reproduced all admitted artifacts.
• Admitted artifacts and the final pack pass Linux and Windows validation.
• Untouched off-grid interpolation error is measured.
• Solver, interpolation, and storage errors are separated.
• Downstream error ownership is explicit without fabricated derivatives.
• The immutable pack has exact file checksums and a versioned manifest.
• Runtime use requires neither libRadtran nor network access.
• The first-pack domain and fail-closed boundaries are explicit.
• A source-controlled closure receipt binds all admitted checkpoints.

Explicitly Unchanged

• no engine calculation, native code, facade, serializer, REST model, route, or OpenAPI contract changed;
• no engine loader exists yet;
• no table or CIE dataset entered the MIT wheel;
• no package dependency, default policy, or legacy output changed;
• no tag, package release, website install, or deployment occurred; and
• Phase 2 implementation has not begun.

Next Authorized Work

Phase 2 may implement the Python spectral single-epoch truth layer against an explicit caller-supplied, independently validated pack. It must enforce the pack's exact domain and compatibility ID, preserve typed not_evaluable results, and leave event-time solving to Phase 3.