Mitsuru SOMA
National Astronomical Observatory
Mitaka, Tokyo 181, Japan

Internet: PSOMAXX@C1.mtk.nao.ac.jp
Tel: +81-422-34-3788
Fax: +81-422-32-1924



Issues of the Physical Ephemerides

Abstract.  In the Astronomical Almanac  the  planetographic coordinates  of
the sub-Earth points are tabulated.  These coordinates are calculated  from
the geocentric positions of the planets affected by the stellar aberration.
Discussion is made  about the errors produced from this calculation method.
Attention should also be drawn to the inconsistency of the dates of passage
of the  Earth  through  Saturn's ring-plane  given  in the Almanac  and the
ephemeris of rings of Saturn.  Discussion is also made  about the confusion
present  in the physical ephemeris of the Sun  and some procedure is recom-
mended about changing the formulae for the prime meridian when adopted pole
positions are changed.