Description
Return Julian-day fractions since noon and midnight.
Astronomical day origins and leap-second notation depend on an explicit time scale and context. A numerical day fraction or second token does not itself verify UTC leap-second occurrence or convert between time standards.
Return Julian-day fractions since noon and midnight.
When to use this tool
Use Date: Astronomical Noon Day Fraction when checking the stated astronomical-day or leap-second display convention.
How to use the tool and how it works
- Enter julianDay. Use the units and conventions below.
- Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
- Read result. Expand result to inspect the returned fields.
Return Julian-day fractions since noon and midnight. Require julianDay in [0,1000000000]; fractionSinceNoon is modulo one and fractionSinceMidnight is (day+0.5) modulo one.1
| Input field | Meaning and units | Accepted input |
|---|---|---|
| julianDay | Julian day number with noon origin; the numeric input alone does not identify its time scale. | Required. Finite number. |
| Output field | Interpretation | Returned shape |
|---|---|---|
| result | Returned object; expand its named members below. | Required. Object. |
| result.fractionSinceNoon | Fraction Since Noon | Calculated result member: number. |
| result.fractionSinceMidnight | Nonnegative fractional part of julianDay+0.5; differs from the noon-origin fraction. | Calculated result member: number. |
{
"input": {
"julianDay": 2451545
},
"output": {
"result": {
"fractionSinceNoon": 0,
"fractionSinceMidnight": 0.5
}
}
}Limitations and assumptions
- No astronomical time scale, civil date, UTC leap-second handling or observation timestamp is inferred.
- Outputs are nested inside result. Inputs must satisfy both the field types and the cross-field conditions above. Invalid input causes an error; a successful false flag or documented placeholder is a different result.
- Numeric calculations use binary floating point unless exact decimal-integer arithmetic is explicitly stated. No hidden measurement tolerance or decimal rounding is added; nonfinite or out-of-contract results are rejected. Numeric signed-zero results are exported as zero.
Alternative or Complementary methods
Use appropriate time-scale conversion and authoritative leap-second data for actual scientific timestamps.
References
Similar or alternative tools
- Era Boundary Day Gap
Return elapsed days from a supplied era boundary.
- Day Fraction Midnight Wrap
Add day fractions and separate a signed whole-day carry.