Julian dates assign a unique number to each calendar
day. The Julian day number counts the number of days since noon on
January 1, -4712 (astronomical calendar) or January 1, 4713 BC (civil
calendar). This system, widely used by astronomers, was proposed by
Julius J. Scaliger in 1583. Hours and minutes are counted as fractions
of a day since the last noon (Universal Time).
The Julian dates provided by the PACIFIC Exchange
Rate Service are only provided as integer numbers for the particular
day at noon Universal Time (i.e., Greenwich Mean Time, London, UK).
However, the noon spot rates are all Eastern Standard Time (EST) or
Eastern Daylight Savings Time (EDT). As noon Eastern Time occurs
five hours after noon Greenwich Time, it is necessary to add 0.208333 to
obtain the correct Julian day.
For more information, please visit the
Julian Date Converter web page
of the U.S. Naval Observatory Astronomy Applications Department.
converter can be used to convert calendar dates into