If no MJD is entered in this field, the default finals2000A.data file will be used to supply the polar motion, UT1-UTC, and celestial pole offsets (the EOP quantities). These quantities can not be computed mathematically with models to the accuracy that are typically required. Therefore, nearly daily observational updates are required, along with good model estimates. The finals2000A.data is updated weekly and contains a combined solution of observational data, dating back to January, 1, 1992, and predictions approximately 1 year into the future. Since this file is updated weekly, recent past combination data for dates going back for about 100 days may change slightly, and, of course, estimates in the future will change.

If a Modified Julian Date (MJD) is entered in this field, the EO Matrix Calculator software will use the finals2000A.daily file which was produced on that date instead of the finals2000A.data file. Note however, no finals2000A.daily files are available for use by the calculator 100 days prior to the date of the request. At the chosen MJD, the finals2000A.daily file contained the best estimate of the EOP quantities at that time. The finals2000A.data file should have improved estimates over the finals2000A.daily file for past dates.