Circumpolar Declination Threshold By Latitude
Geometriccircumpolarthresholdsamehemispheredec|δ|≥90−|φ|,boundaryhorizontangent,refractionexcluded. Actual independent model/unit/frame/epoch/calibration and applicable measurement established;not precise ephemeris,forecast,geodesy operation,identity or safety approval.
Description
Circumpolar geometry describes declinations that remain on the visible side of an ideal horizon during rotation.
Circumpolar geometry describes declinations that remain on the visible side of an ideal horizon during rotation.1
This tool returns the absolute declination boundary and applicable hemisphere from latitude, rather than checking a particular star.
When to use Circumpolar Declination Threshold By Latitude
Use this tool to apply the stated circumpolar declination threshold by latitude operation with an explicit input and unit basis.
How to use Circumpolar Declination Threshold By Latitude and how it works
- Establish the measurement basis and units described above.
- Enter actualLatitudeDegrees and run the tool.
- Read result.minimumCircumpolarAbsoluteDeclinationDegrees, result.circumpolarHemisphere using the output meanings below.
- If input is rejected, correct the stated type, range, ordering or alignment issue and rerun; review successful results under the declared convention.
| Input field | Meaning | Value type | Requirement |
|---|---|---|---|
| actualLatitudeDegrees | Latitude Degrees. Units, ordering and applicable branch are specified in the algorithm. | number | required; finite; further conditions in the algorithm |
Require latitude strictly between −90 and 90 degrees and exclude zero. Return 90−abs(latitude) and north or south according to its sign; equality is a horizon-tangent boundary and real visibility also depends on horizon and refraction.
circumpolar boundary abs(declination) = 90−abs(latitude), in the observer’s hemisphere Apply the declared units, ordering and branch conditions.
| Output field | Meaning | Value type |
|---|---|---|
| result | Object containing the declared output fields. | object |
| result.minimumCircumpolarAbsoluteDeclinationDegrees | Absolute declination threshold in degrees, including the tangent boundary. | number |
| result.circumpolarHemisphere | north or south according to the observer latitude. | string |
{
"input": {
"actualLatitudeDegrees": 30
},
"output": {
"result": {
"minimumCircumpolarAbsoluteDeclinationDegrees": 60,
"circumpolarHemisphere": "north"
}
}
}Limitations and assumptions
The output applies the declared operation to the values you supply. Establish the measurement basis, units, coefficients and any caller-selected rules before interpreting it. The tool does not independently collect or verify observations or decide whether a model or reference applies.
Supply explicit required fields with the documented types and dense aligned arrays. Unknown fields, wrong types and nonfinite numbers are rejected. Branch-specific constraints are explained above. A returned boolean, signed difference or tied result follows the stated convention; an input error instead means the required input contract was not satisfied. Very large inputs or outputs may be rejected by shared resource limits.
Alternative or Complementary methods
For a related operation, use Maximum Transit Altitude Calculator. A star’s upper meridian transit is its highest altitude during an ideal diurnal circle.
For a related operation, use Celestial Equator Altitude By Latitude. The celestial equator’s upper meridian intersection has an altitude determined by observer latitude.
References
Similar or alternative tools
- Maximum Transit Altitude Calculator
A star’s upper meridian transit is its highest altitude during an ideal diurnal circle.
- Celestial Equator Altitude By Latitude
The celestial equator’s upper meridian intersection has an altitude determined by observer latitude.