Overview

Julian epoch


'Julian epoch' can also refer to...

 

More Like This

Show all results sharing this subject:

  • Astronomy and Astrophysics

GO

Show Summary Details

Quick Reference

A method of specifying the date as a year with a decimal part, as for example in 1995.5. The unit is the Julian year of 365.25 days and the time-scale used is Barycentric Dynamical Time (TDB). It is often convenient to use the standard epoch, J2000.0, for example, in star catalogues. The prefix ‘J’ is added to distinguish this epoch from the more complicated Besselian epoch used prior to 1984. The standard epoch is defined as

J2000.0 = 2000 January 1.5 = 2000 January 1 12 h TDB

The date for other epochs can be calculated from this. For example, J1999.0 is exactly 365.25 days earlier, that is, 1999 January 1.25.

Subjects: Astronomy and Astrophysics.


Reference entries

Users without a subscription are not able to see the full content. Please, subscribe or login to access all content.