Passage: A Julian year should not be confused with the Julian day (also Julian day number or JDN), which is also used in astronomy.  Despite the similarity of names, there is little connection between the two. It is a way of expressing a date as the integer number of days that have elapsed since a reference date or initial epoch. The Julian day uniquely specifies a date without reference to its day, month, or year in any particular calendar. A specific time within a day is specified via a decimal fraction.

Question: What is another name for the Julian day?
JDN