Bortle Class Sky Magnitude Lookup

Independently verified site/observer/definition Bortle and limiting magnitude reference; ordinal class not an exact sky luminance. Exact independently verified context/edition key; not embedded or live reference data. Model only, not an ephemeris, measured stellar identity or observational guarantee.

Description

Bortle descriptions and measured sky brightness are related but different quantities.

Bortle descriptions and measured sky brightness are related but different quantities.^[1]

A supplied reference should preserve its observing conditions and measurement convention. Use Bortle Class Sky Magnitude Lookup to retrieve an exact caller-supplied reference entry.

When to use Bortle Class Sky Magnitude Lookup

Use Bortle Class Sky Magnitude Lookup to retrieve an exact caller-supplied reference entry. Choose an independently reviewed reference for the exact historical, cultural or technical context, then supply its keys and texts.

How to use Bortle Class Sky Magnitude Lookup and understand its results

Choose an independently reviewed reference for the exact historical, cultural or technical context, then supply its keys and texts.
Enter Caller verified bortle sky keys, Caller verified bortle sky notices, Query bortle sky key using the field table and validation rules below, then run the tool.
Read Matched caller notice; interpret the units, signs, ordering and unknown-value placeholders described below.
Correct reported input errors and rerun. Apply successful results according to their specific meanings and check the assumptions before using them in a decision.

Input field	Meaning	Value type	Requirement
callerVerifiedBortleSkyKeys	Caller verified bortle sky keys	array of string	Required; constraints below
callerVerifiedBortleSkyNotices	Caller verified bortle sky notices	array of string	Required; constraints below
queryBortleSkyKey	Query bortle sky key	string	Required; constraints below

Provide aligned, nonempty arrays of reference keys and independently verified notices, then enter the exact query key. Keys must be unique, nonblank and at most 128 UTF-16 code units long; notices must be nonblank. Matching is case sensitive and does not trim the query or returned text. The matching notice is returned unchanged; an unknown key is an input error. The reference contents and their applicability are supplied by the caller; the tool does not retrieve external records or verify source authority.

matched reference = suppliedTexts[indexOfExactQueryKey(suppliedKeys)]

Use the field order, units and branch conditions described above.

Output field	Meaning	Value type
matchedCallerNotice	Exact caller-supplied notice, unchanged and unverified.	string

json

{
  "input": {
    "callerVerifiedBortleSkyKeys": [
      "context-a/edition-a",
      "context-a/edition-b"
    ],
    "callerVerifiedBortleSkyNotices": [
      "independently verified reference a",
      "independently verified reference b"
    ],
    "queryBortleSkyKey": "context-a/edition-b"
  },
  "output": {
    "matchedCallerNotice": "independently verified reference b"
  }
}

Limitations and assumptions

A supplied reference should preserve its observing conditions and measurement convention. Apply the exact scope and assumptions explained above.

All listed fields require explicit values. Unexpected fields, incorrect types, nonfinite numbers and sparse arrays fail validation. Domain-specific bounds, alignments and supported tokens are explained above; extremely large inputs or outputs can also be rejected. Input errors differ from successful false results, empty match lists and unknown-evidence placeholders.

Alternative or Complementary methods

Use Limiting Magnitude From Aperture for a related task: Limiting magnitude depends on observing conditions as well as aperture.

Use Star Count Limiting Magnitude Band for a related task: Visible-star counts depend on a defined sky sample and limiting-magnitude observations.

References

Bortle Class Sky Magnitude Lookup — tool.io

Similar or alternative tools

Limiting Magnitude From Aperture
Limiting magnitude depends on observing conditions as well as aperture.
Star Count Limiting Magnitude Band
Visible-star counts depend on a defined sky sample and limiting-magnitude observations.