Displays a Julian Day Calculator to compute the (geocentric) Julian Date corresponding to a particular Calendar Date and vice versa.



To convert a Calendar date to a Julian date


Enter the Calendar Date in the frame Calendar Date. Two options exist : 

    • Check the Use day fraction format box, then enter the day with decimals in the Day field, and leave Hour, Min and Sec empty. Click the down-arrow button. The corresponding Geocentric Julian Date will appear in the lower section.

    • Uncheck the Use day fraction format box and enter the Year, Month, Day, Hour, Minutes and Seconds values.  Then click the down-arrow button, as described above.


To convert a Julian date to a Calendar date 

    • Enter the Geocentric Julian Date in the bottom section and click the up-arrow button. The corresponding Calendar date appears in the upper section. 

    • If the Use day fraction format box is checked, the Day will be displayed in fractional format (day with decimals). If not, the Hour, Minutes and Seconds fields will be completed. 

Clicking the Time Now (UT) button will update all fields to show the current Calendar date and Geocentric Julian date.