code: function getShubun(year) {
    if (year < 1948 || 2099 < year) {
      return null;
    }
    var day;
    switch(year % 4) {
    case 0:
      day = year <= 2008 ? 23 : 22;
      break;
    case 1:
      day = year <= 1917 ? 24 : year <= 2041 ? 23 : 22;
      break;
    case 2:
      day = year <= 1946 ? 24 : year <= 2074 ? 23 : 22;
      break;
    case 3:
      day = year <= 1979 ? 24 : 23;
    }
    return [9, day, '秋分の日'];
  }
docs: 秋分の日 (wikiの簡易計算より)
  @method getShubun
  @param  {Number}  year
  @return {Array}   shubun