What's your definition of Julian Date?
Assuming it's yyyy-ddd, where ddd is a value between 1 and 365 (366 in leap
years), so that today is 2004-173, you can add the value of ddd to Dec.
31st of the previous year:
DateAdd("d", 173, #12/31/2003#)
If you mean a true Julian Date (a continuous count of days and fractions
since noon Universal Time on January 1, 4713 BCE (on the Julian calendar)),
it's a bit more difficult.