code: private static int getCycleNumber(long epochDay) {
          Long[] days = ADJUSTED_CYCLES;
          int cycleNumber;
          try {
              for (int i = 0; i < days.length; i++) {
                  if (epochDay < days[i].longValue()) {
                      return i - 1;
                  }
              }
              cycleNumber = (int) epochDay / 10631;
          } catch (ArrayIndexOutOfBoundsException e) {
              cycleNumber = (int) epochDay / 10631;
          }
          return cycleNumber;
      }
docs: Returns the 30 year cycle number from the epoch day.
  
  @param epochDay  an epoch day
  @return a cycle number