Question about caldate_mjd()

Bart Grantham <[email protected]> Sun, 14 Sep 2003 22:25:45 -0400
Newsgroups gmane.comp.lib.libtai
Message-ID <[email protected]>
What date is this calibrated against?  Something, 1859?  I guess I could 
easily figure out the exact date, but the reason I ask is: what is the 
significance of that date?  Is that when some major time reference was 
established?  Leap year rules, perhaps?  Thanks for the help.