public Range GetCurrentRangeAtTime( 
   TimeSpan time
)

public Task<List<ArcGIS.Desktop.Mapping.Range>> GetInterpolatedMapRanges()
{
  //Return the collection representing the map time for each frame in animation.
  return QueuedTask.Run(() =>
  {
    var mapView = MapView.Active;
    if (mapView != null || mapView.Animation == null)
      return null;

    var animation = mapView.Map.Animation;

    var ranges = new List<ArcGIS.Desktop.Mapping.Range>();
    //We will use ticks here rather than milliseconds to get the highest precision possible.
    var ticksPerFrame = Convert.ToInt64(animation.Duration.Ticks / (animation.NumberOfFrames - 1));
    for (int i = 0; i < animation.NumberOfFrames; i++)
    {
      var time = TimeSpan.FromTicks(i * ticksPerFrame);
      //Because of rounding for ticks the last calculated time may be greeting than the duration.
      if (time > animation.Duration)
        time = animation.Duration;
      ranges.Add(mapView.Animation.GetCurrentRangeAtTime(time));
    }
    return ranges;
  });
}