Day (JD), the numeric is right; the marker number of days passed from the origin specified in the calendar .

The Origin time is exactly noon on the first Monday of January of the year 4713 BC. That day marked the day of Zero is placed, and with the elapse of each day, a number to this counter will be added. To show more accurate time can be of the numbers a fraction is also used. Day for negative number (for the days before the origin) is applicable.

this calendar first, by astronomers in order to put a quantity number for register events, offer Patrol, and then another group, also using it ... of it, such as in sailing, and protocols of telecommunications. It should be noted that the day no communication with the calendar .