The Calendar
What the atlas records for this date, across the traditions it covers.
Observed On This Date
Falls on the 256th day of the year: 13 September in a common year, 12 September in a leap year. The number 256 is 2 to the 8th power, the count of distinct values a byte can represent, a number well known to programmers.
Dates for the Hebrew and Islamic calendars are the tabular reckoning, which is what a printed calendar prints. Communities that begin a month on a sighted crescent may differ by a day, and differ from one another by place.