Stellar Parallax Distance

Inspectable records

Ledger state

The current ledger marks this instrument verified clean within the source-bound verification corpus.

Area

Earth & Space

Tranche

tranche-2

Evidence ID

t2-029

Ledger rows

1

No ledger note is attached.

Review findings

The core reciprocal formula is standard, but the specification is incomplete because it accepts either arcsec or mas without defining unit handling and advertises ly and AU without specifying conversion formulas. These ambiguities must be resolved before approval.

Formula and scope findings

• d(pc)=1/p(arcsec) is correct for positive parallax expressed in arcseconds, subject to the small-angle approximation.
• If the input is in milliarcseconds, the required formula d(pc)=1000/p(mas) is not stated explicitly.
• Formulas or conversion constants for the advertised outputs in light-years and AU are missing.
• The specification does not define behavior for zero or negative measured parallax, which can occur because of measurement noise.

Unit assumptions

• For parallax p in arcseconds, distance is d(pc)=1/p.
• For parallax p in milliarcseconds, distance is d(pc)=1000/p.
• Conversions used here are 1 pc=3.26156 ly and 1 pc=206264.806247 AU.
• Parallax must be a positive angle; zero is undefined and negative measured parallax is not a physical distance input.
• The parsec reciprocal formula uses the small-angle approximation; an exact geometric calculation would use d(AU)=1/tan(p in radians).

Boundary hardening

BREAK_CLAIMED · SELF_FLAGGED

The instrument breaks or becomes hazardous at zero parallax because division is undefined, at very large parallax because the small-angle formula diverges from the finite-angle geometric result, and for negative parallax because signed arithmetic produces an unphysical negative distance unless the input is rejected or specially interpreted.

Errata and corrections

No applied erratum is attached to this unique-name record.

Inspectable example

4 review vectors are recorded. One source-bound sample is shown below.

{
  "inputs": {
    "parallax": 0.1,
    "parallax_unit": "arcsec"
  },
  "expected_outputs": {
    "distance_pc": 10,
    "distance_ly": 32.6156,
    "distance_AU": 2062648.06247
  },
  "working": "1) d(pc)=1/0.1=10 pc. 2) d(ly)=10×3.26156=32.6156 ly. 3) d(AU)=10×206264.806247=2062648.06247 AU."
}

Related workflows

No source-defined multi-instrument workflow membership is recorded.

Sources and evidence

These pointers bind the page to evidence. They do not grant authority or collapse verification into deployment.

• VERIFIED_LEDGER.json · VERIFIED_CLEAN
• evidence-tranche2/tranche2-results.json
• BOUNDARY_HAZARD_CATALOG.json