code: function getSunLongitude (dayNumber, timeZone) {
    return Math.floor(SunLongitude(dayNumber - 0.5 - timeZone / 24.0) / Math.PI * 12)
  }
docs: /* Compute the sun segment at start (00:00) of the day with the given integral Julian day number.
  The time zone if the time difference between local time and UTC: 7.0 for UTC+7:00.
  The function returns a number between 0 and 23.
  From the day after March equinox and the 1st major term after March equinox, 0 is returned.
  After that, return 1, 2, 3 ...