Source: https://guthlabs.ai/docs/instruments/telescope-field-of-view/

instrument / verified-clean

# Telescope Field of View

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

Status: **VERIFIED_CLEAN**Lifecycle: **verified-clean**

## Inspectable records

[01**Overview**Purpose and lifecycle](<https://guthlabs.ai/docs/instruments/telescope-field-of-view/>)[02**Mechanism**Method and assumptions](<https://guthlabs.ai/docs/instruments/telescope-field-of-view/mechanism/>)[03**Implementation**Binding and validation](<https://guthlabs.ai/docs/instruments/telescope-field-of-view/implementation/>)[04**Qualification**Evidence and errata](<https://guthlabs.ai/docs/instruments/telescope-field-of-view/qualification/>)

## Ledger state

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

**Area**: Earth & Space (astronomy, orbital mechanics, meteorology, geology, geodesy, oceanography)

**Tranche**: tranche-3

**Evidence ID**: t3-017

**Ledger rows**: 1

No ledger note is attached.

## Review findings

The stated honest label appropriately identifies this as an approximation, but the user-facing name or output should say approximate true field of view unless field-stop and distortion corrections are implemented.

### Formula and scope findings

- AFOV/M is the standard nominal approximation, not an exact true-field formula; actual field of view depends on the eyepiece field stop and optical distortion.

- The phrase "magnification (or focal lengths)" is ambiguous because it does not explicitly identify telescope and eyepiece focal lengths or state that M = telescope focal length / eyepiece focal length.

### Unit assumptions

- AFOV is expressed in degrees.

- Magnification M is dimensionless and must be positive.

- If focal lengths are supplied, telescope and eyepiece focal lengths must use the same units; M = F_telescope / F_eyepiece.

- Convert degrees to arcminutes with 1 degree = 60 arcminutes.

## Boundary hardening

### Recorded hazards

- Division by zero occurs when magnification is zero.

- Zero or negative magnification is physically invalid and should be rejected; focal lengths must be positive.

- The approximation can be inaccurate for eyepieces with significant angular distortion or when the field stop limits the view.

- Very large AFOV-to-magnification results may exceed the physically usable field of the telescope or eyepiece.

## 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": {
    "eyepiece_AFOV_deg": 50,
    "magnification": 100
  },
  "expected_outputs": {
    "true_FOV_deg": 0.5,
    "true_FOV_arcmin": 30
  },
  "working": "TFOV = AFOV / M = 50 / 100 = 0.5 degrees. Arcminutes = 0.5 × 60 = 30 arcminutes."
}
````

## Related workflows

[Telescope Night KitAFOV,M → true FOV](<https://guthlabs.ai/docs/instrument-workflows/telescope-night/>)

## 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-tranche3/tranche3-results.json`