Create JulianDate from dayNumber/secondsOfDay

CesiumJS
1

Am I missing something from the following JulianDate example? I would expect that if I take the days and seconds from a JulianDate to construct a new JulianDate that I would get the same datetime. Instead it is always 37 seconds different and there are only 28 leap seconds so it isn’t leap seconds alone that accounts for the difference.

const viewer = new Cesium.Viewer("cesiumContainer", {
  clockViewModel: new Cesium.ClockViewModel(new Cesium.Clock({
      clockStep: Cesium.ClockStep.SYSTEM_CLOCK
  }))
});

var now = new Cesium.JulianDate.now();
var days = now.dayNumber;
var seconds = now.secondsOfDay;
console.log(Cesium.JulianDate.toIso8601(now));

var copy = new Cesium.JulianDate(days,seconds);
console.log(Cesium.JulianDate.toIso8601(copy));

console.log(Cesium.JulianDate.secondsDifference(copy, now))

Output

2025-07-02T12:30:56.9949999999998909Z
2025-07-02T12:31:33.9949999999998909Z
37
2

Found the solution :person_facepalming:
I needed to add the TimeStandard when constructing the new JulianDate

var copy = new Cesium.JulianDate(days,seconds,Cesium.TimeStandard.TAI);