Computation of an estimate of Delta_T, for astronomical computations with calendars.
Delta_T is defined in this way: UTC = TT - Delta_T, where UTC (formerly GMT) is the master time of all our clocks.
TT is Terrestrial Time, a uniform time scale defined independently from any Earth movements.
Delta_T is erratic and difficult to compute, however, the general trend of Delta_T is due to the braking of the Earth's daily revolution.
This estimate of Deltta_T in seconds from the year expressed in Common Era is a quadratic function of the year.
The computation of the long-term Delta_T is after Morrison and Stephenson 2021.
In this version, the estimated Delta_T is smoothed over time. The result is rounded to the nearest second.
Methods
(static) getDeltaT(theDate) → {number}
Compute an estimate of Delta T, defined as: UTC = TT - Delta T. The estimate is only the quadratic part of Delta T.
Parameters:
| Name | Type | Description |
|---|---|---|
theDate |
Date | date where Delta T is estimated (estimation is per exact date, not per year). |
Returns:
Delta T, unit is milliseconds, result reflects an integer signed number of seconds.
- Type
- number