Although it is also recorded that the day was "first day of the month, " in other word, the day of new moon in Nihonshoki, the record was not taken into consideration in a calculation method of the Meiji Government, because first day of the moon depended on rekiho (method of making calendars) and was not able to be calculated by "kampo" (a simple method).
なお、『日本書紀』はこの日が「朔」、すなわち新月の日であったとも記載しているが、朔は暦法に依存しており「簡法」では計算できないので、明治政府による計算では考慮されなかったと考えられる。