def JD2epochJulian(JD):
#---------------------------------------------------------------------
   """
Convert a Julian date to a Julian epoch

:param JD:
   Julian date
:type JD:
   Floating point number
   
:Returns:
   Julian epoch

:Reference:
   Standards Of Fundamental Astronomy,
   
   http://www.iau-sofa.rl.ac.uk/2003_0429/sofa/epj.html

:Notes:
   e.g. ``2445700.5 converts into 1983.99863107``
   Assuming years of exactly 365.25 days, we can
   calculate a Julian epoch from a Julian date.
   Expression corresponds to IAU SOFA routine 'epj'

   """
#----------------------------------------------------------------------
   return 2000.0 + (JD - 2451545.0)/365.25