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\write 0 {2.  CONVENTIONAL DYNAMICAL REFERENCE FRAME
\noexpand\dotfill\the\pageno\noexpand\break}
\noindent{\large CHAPTER 2} {\bf CONVENTIONAL DYNAMICAL REFERENCE FRAME}
\bigskip

The planetary and lunar ephemerides recommended for the IERS
standards are the JPL Development Ephemeris DE403 and the Lunar
Ephemeris LE403 (Standish {\it et al.}, 1995).  The reference frame of
these new ephemerides is that of ICRF.  The ephemerides have been 
adjusted to all relevant observational data, including recent
observations taken with respect to the IERS frame.  It is expected that
DE403/LE403 will eventually replace DE200/LE200 (Standish, 1990) as the
basis for the international almanacs.

Table 2.1 shows the IAU 1976 values of the planetary masses and the 
values used in the creation of both DE200/LE200 and of DE403/LE403.
Also shown in the table are references for the DE403 set, the current
best estimates.

Also associated with the ephemerides is the set of astronomical
constants used in the ephemeris creation; these are listed in 
Table 2.2.  

The constants which are provided directly with the ephemerides 
should be considered to be an integral part of them; they will 
sometimes differ from a more standard set, but the differences
are necessary for the optimal fitting of the data.

\noindent{\bf Availability of DE403}

Sections of DE403 are now available from the anonymous ftp site:
``navigator.jpl.nasa.gov" [128.149.23.82]. For a ``navio" version
(in-house JPL format), the following ``navio" and ``nioftp" versions
are available, covering 1980-2010:

``navigator:/ephem/navio/de403s" and ``navigator:/ephem/navio/de403s.ftp"

\noindent For other time-spans, contact F A McCreary (faith@viviane.jpl)
or E M Standish (ems@smyles.jpl). An outside user is advised to first
get and read the file, ``navigator:/ephem/export/READ.ME"; it should
answer most questions about retrieving and using the JPL ephemerides.


\bigskip
\noindent Table 2.1.  1976 IAU, DE200 and DE403 planetary mass values, 
expressed in reciprocal solar masses. 
\hrule

\vskip 0.03in
\halign{# \hfil &\kern.1pc\hfil#&#\hfil&\kern.1pc\hfil#&#\hfil&\kern.1pc\hfil#&#\hfil&
\quad \kern.5pc#\hfil\cr
\noalign {\vskip 0.03in}
Planet&1976 IAU && DE200 && DE403 && Reference for DE403 value\cr
\noalign {\vskip0.05in \hrule \vskip0.05in}
Mercury       &6023600.&&6023600.&& 6023600.&& Anderson {\it et al.}, 1987\cr
Venus         &408523.&5&408523.&5&408523.&71& Sjogren {\it et al.}, 1990\cr
Earth \& Moon &328900.&5&328900.&55& 328900.&560392...& Williams {\it et al.}, 1995\cr
Mars          &3098710.&&3098710.&&3098708.&& Null, 1969\cr
Jupiter       &1047.&355&1047.&350&1047.&3486& Campbell and Synott, 1985\cr
Saturn        &3498.&5&3498.&0&3497.&898& Campbell and Anderson, 1989\cr
Uranus        &22869.&&22960.&&22902.&98& Jacobson {\it et al.}, 1992\cr
Neptune       &19314.&&19314.&&19412.&24& Jacobson {\it et al.}, 1991\cr
Pluto         &3000000.&& 130000000.&&135200000.&& Tholen and Buie, 1996\cr}
\hrule

\vfil \eject
\noindent Table 2.2.  Auxiliary constants from the JPL Planetary and Lunar 
Ephemerides DE403/LE403.
\hrule
\smallskip
\halign{\kern 2pc#\hfil&\kern 1pc#\hfil\cr
          Scale (km/au)             &    149597870.691\cr
          Scale (secs/au)           &    499.0047838061...\cr
          Speed of light (km/sec)   &    299792.458\cr
          Obliquity of the ecliptic &    $23^\circ 26' 21\qd412$\cr
          Earth-Moon mass ratio     &    81.300585\cr
          GM$_{Ceres}$              &    4.64 $\times 10^{-10} $GM$_{Sun}$\cr
          GM$_{Pallas}$             &    1.05 $\times 10^{-10} $GM$_{Sun}$\cr
          GM$_{Vesta}$              &    1.34 $\times 10^{-10} $GM$_{Sun}$\cr
          density$_{class C}$       &    1.80\cr
          density$_{class S}$       &    2.40\cr
          density$_{class M}$       &    5.00\cr
}
\smallskip
\hrule
\bigskip

\everypar={\hangindent=24pt \hangafter=1}

\noindent{\bf References}

\nobreak

\item{}\kern-2pc
Anderson, J. D., Colombo, G., Esposito, P. B., Lau, E. L., and
Trager, G. B., 1987, ``The Mass Gravity Field and Ephemeris
of Mercury," {\it Icarus}, {\bf 71}, pp. 337--349.

\item{}\kern-2pc
Campbell, J. K. and Anderson, J. D., 1989, ``Gravity Field of the
Saturnian System from Pioneer and Voyager Tracking Data,"
{\it Astron. J.}, {\bf 97}, pp. 1485--1495.

\item{}\kern-2pc
Campbell, J. K. and Synott, S. P., 1985, ``Gravity Field of the
Jovian System from Pioneer and Voyager Tracking Data,"
{\it Astron. J.}, {\bf 90}, pp. 364--372.

\item{}\kern-2pc
Jacobson, R. A., Riedel, J. E. and Taylor, A. H., 1991, ``The Orbits of 
Triton and Nereid from Spacecraft and Earth-based Observations'',
{\it Astron. Astrophys.}, {\bf 247}, pp. 565--575.


\item{}\kern-2pc
Jacobson, R. A., Campbell, J. K., Taylor, A. H. and Synnott, S. P., 
1992, ``The Masses of Uranus and its Major Satellites from Voyager 
Tracking Data and Earth-based Uranian Satellite Data'', 
{\it Astron J.}, {\bf 103}(6), pp. 2068--2078.

\item{}\kern-2pc
Null, G. W., 1969, ``A Solution for the Mass and Dynamical Oblateness
of Mars Using Mariner-IV Doppler Data," {\it Bull. American
Astron. Soc.}, {\bf 1}, p. 356.

\item{}\kern-2pc
Sjogren, W. L., Trager, G. B., and Roldan G. R., 1990, ``Venus:  A
Total Mass Estimate," {\it Geophys. Res. Let.}, {\bf 17},
pp. 1485--1488.

\item{}\kern-2pc
Standish, E. M., 1990, ``The Observational Basis for JPL's DE200,
the Planetary Ephemerides of the Astronomical Almanac,"
{\it Astron. Astrophys.}, {\bf 233}, pp. 252--271.

\item{}\kern-2pc
Standish, E. M., Newhall, X X, Williams, J. G. and Folkner, W. F., 
1995, ``JPL Planetary and Lunar Ephemerides, DE403/LE403," 
JPL IOM 314.10-127, to be submitted to {\it Astron. Astrophys.}

\item{}\kern-2pc
Tholen, D. J. and Buie, M. W., 1996, ``The Orbit of Charon.  I. New 
Hubble Space Telescope Observations", submitted to {\it Icarus}.

\item{}\kern-2pc
Williams, J. G., Newhall, X X, and Standish, E. M., 1995, (result from
least squares adjustment of DE403/LE403).

\everypar={}

\vfil\eject
