DateTime.utc(int year, [ int month = 1, int day = 1, int hour = 0, int minute = 0, int second = 0, int millisecond = 0, int microsecond = 0 ])

Constructs a DateTime instance specified in the UTC time zone.

DateTime dDay = new DateTime.utc(1944, DateTime.JUNE, 6);

Source 

DateTime.utc(int year,
    [int month = 1,
    int day = 1,
    int hour = 0,
    int minute = 0,
    int second = 0,
    int millisecond = 0,
    int microsecond = 0])
    : this._internal(year, month, day, hour, minute, second, millisecond,
          microsecond, true);