Solar Noon Equation-of-Time Correction
Declaredlocalsolarnoonminutesafterlocalstandardmidnight=720−4(λ−λzone)−EOT,true-minusmeanEOTpositiveSunfast;DSTexcluded. Actual independent model/unit/frame/epoch/calibration and applicable measurement established;not precise ephemeris,forecast,geodesy operation,identity or safety approval.
Description
Solar noon differs from noon on a standard clock because of longitude and the equation of time.
Solar noon differs from noon on a standard clock because of longitude and the equation of time.1
This calculator uses east-positive longitude and a true-minus-mean equation-of-time convention to return minutes after local standard midnight.
When to use Solar Noon Equation-of-Time Correction
Use this tool to apply the stated solar noon equation-of-time correction operation with an explicit input and unit basis.
How to use Solar Noon Equation-of-Time Correction and how it works
- Establish the measurement basis and units described above.
- Enter actualEastLongitudeDegrees, callerEastStandardMeridianDegrees, callerIndependentEquationOfTimeMinutes and run the tool.
- Read result.value 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 |
|---|---|---|---|
| actualEastLongitudeDegrees | East Longitude Degrees. Units, ordering and applicable branch are specified in the algorithm. | number | required; finite; further conditions in the algorithm |
| callerEastStandardMeridianDegrees | East Standard Meridian Degrees. Units, ordering and applicable branch are specified in the algorithm. | number | required; finite; further conditions in the algorithm |
| callerIndependentEquationOfTimeMinutes | Equation Of Time Minutes. Units, ordering and applicable branch are specified in the algorithm. | number | required; finite; further conditions in the algorithm |
Require longitude and standard meridian within ±180 degrees. Subtract four minutes per degree of longitude offset and the supplied equation of time from 720; do not apply daylight saving, choose a timezone or wrap the result into a day.
standardNoonMinutes = 720−4(longitudeEast−standardMeridianEast)−equationOfTimeMinutes Apply the declared units, ordering and branch conditions.
| Output field | Meaning | Value type |
|---|---|---|
| result | Object containing the declared output fields. | object |
| result.value | Minutes after local standard midnight, with no daylight-saving correction or day wrapping. | number |
{
"input": {
"actualEastLongitudeDegrees": 5,
"callerEastStandardMeridianDegrees": 0,
"callerIndependentEquationOfTimeMinutes": -10
},
"output": {
"result": {
"value": 710
}
}
}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 Daylight Duration Latitude Calculator. Geometric daylight uses the solar center crossing an ideal zero-altitude horizon.
For a related operation, use Civil Twilight End Hour Angle. Civil twilight conventionally uses the solar center six degrees below a geometric horizon.
References
-
Solar Noon Equation-of-Time Correction — tool.io
Similar or alternative tools
- Daylight Duration Latitude Calculator
Geometric daylight uses the solar center crossing an ideal zero-altitude horizon.
- Civil Twilight End Hour Angle
Civil twilight conventionally uses the solar center six degrees below a geometric horizon.