Orientation of the JPL Ephemerides, DE 200/LE 200, to the dynamical equinox of J 2000

The lunar and planetary ephemerides, DE 200/LE 200 have been recently produced at JPL. They will form the basis of the ephemerides in the 'Astronomical Almanac' starting in the year 1984. The origin has been referenced to the J 2000 dynamical equinox of the ephemerides themselves. The procedure for this orientation is described here in detail. Analyses of the ephemerides also provide comparisons with the equinox of the FK 4 and with presently adopted values for the earth's obliquity.