<!doctype html public "-//W3C//DTD W3 HTML//EN">
<html><head><style type="text/css"><!--
blockquote, dl, ul, ol, li { padding-top: 0 ; padding-bottom: 0 }
--></style><title>New Planetary and Lunar Ephemeris DE418 is
available</title></head><body>
<div>August 11, 2007</div>
<div><br></div>
<div>JPL's Solar System Dynamics Group has released the DE418
planetary and lunar ephemeris. This has been converted to SPICE SPK
format as for all previous DExxx ephemerides. The conversion does not
involve a loss of precision.</div>
<div><br></div>
<div>de418.bsp is available from the NAIF server at this
location:</div>
<div><br></div>
<div><font size="+1"> <font face="Lucida Grande" color="#000000">
ftp://naif.jpl.nasa.gov/pub/naif/generic_kernels/spk/planets/</font></font
></div>
<div><br></div>
<div>The file (kernel) covers the period:</div>
<div><br></div>
<div>Start: 1899 DEC 04</div>
<div>End: 2051 JAN 21.</div>
<div><br></div>
<div>The file requires just over 16 Mbytes of disk space.</div>
<div><br></div>
<div>The file contains ephemerides for the traditional set of SPICE
ephemeris objects:</div>
<div><br></div>
<div>NAIF ID Object
Name</div>
<div>-------
--------------------</div>
<div
>0 <span
></span> SOLAR SYSTEM BARYCENTER</div>
<div><font size="-4"
color="#000000"
>1 <span
></span> MERCURY BARYCENTER </font></div>
<div><font size="-4"
color="#000000"
>2 <span
></span> VENUS
BARYCENTER <span
></span> </font></div>
<div><font size="-4"
color="#000000"
>3 <span
></span> EARTH
BARYCENTER <span
></span> </font></div>
<div><font size="-4"
color="#000000"
>4 <span
></span> MARS
BARYCENTER <span
></span> </font></div>
<div><font size="-4"
color="#000000"
>5 <span
></span> JUPITER
BARYCENTER <span
></span> </font></div>
<div><font size="-4"
color="#000000"
>6 <span
></span> SATURN
BARYCENTER <span
></span> </font></div>
<div><font size="-4"
color="#000000"
>7 <span
></span> URANUS
BARYCENTER <span
></span> </font></div>
<div><font size="-4"
color="#000000"
>8 <span
></span> NEPTUNE
BARYCENTER <span
></span> </font></div>
<div><font size="-4"
color="#000000"
>9 <span
></span> PLUTO
BARYCENTER <span
></span> </font></div>
<div><font size="-4"
color="#000000"
>10 <span
></span>
SUN <span
></span
> <span
></span> </font></div>
<div><font size="-4"
color="#000000"
>199 <span
></span> MERCURY (equivalent to 1,
Mercury
barycenter) <span
></span
> </font
></div>
<div><font size="-4"
color="#000000"
>299 <span
></span> VENUS (equivalent
to 2, Venus
barycenter) <span
></span
> <span
></span> </font></div>
<div><font size="-4"
color="#000000"
>301 <span
></span>
MOON <span
></span
> <span
></span> </font></div>
<div><font size="-4"
color="#000000"
>399 <span
></span>
EARTH <span
></span
> <span
></span> </font></div>
<div><font size="-4"
color="#000000"
>499 <span
></span> MARS
(equivalent to 4, Mars
barycenter) <span
></span
> <span
></span> </font></div>
<div><br></div>
<div>This is a binary kernel, made on a PC/Linux box using the IEEE
Little Endian binary standard. Because all modern SPICE Toolkits
contain run-time translation for binary SPK files, this binary file
may be used as is on any machine other than a DEC VAX or DEC Alpha.
If you are using a Sun or other Unix box and wish to convert it to
native binary format--IEEE Big Endian--you can easily do so using the
pair of Toolkit utilities named "toxfr" and "tobin,"
run in that order. Or you may use the "bingo" utility
available only from the NAIF website:</div>
<div><br></div>
<div><font face="Lucida Grande" size="+1"
color="#000000">http://naif.jpl.nasa.gov/naif/utilities.html</font></div
>
<div><font face="Lucida Grande" size="-4"
color="#000000"><br></font></div>
<div><font color="#000000"><br></font></div>
<div><font color="#000000">The authors of de418 have prepared an
extensive set of release notes about how the file was produced and how
it compares to earlier dexxx files. As this document has not yet been
cleared for public release it is not currently available from the NAIF
server. However NAIF will make it available "next to" the
SPK file as soon as clearance is obtained. In the meantime a few
words about the file are contained in the de418.cmt text
file.</font></div>
<div><font color="#000000"><br></font></div>
<div><font color="#000000">Those interested in doing their own
statistical comparison of the ephemeris data within de418 with the
ephemeris data from any earlier dexxx file may do so using the
(comparatively new) SPICE application program named
"spkdiff." This program and its User's Guide may be
obtained under the Utilities link on the NAIF web pages (see above for
URL).</font></div>
<div><font color="#000000"><br></font></div>
<div><font color="#000000"><br></font></div>
<div><font color="#000000"><br></font></div>
<div><font color="#000000">Related SPICE Products yet to be
Produced</font></div>
<div><font
color="#000000">-----------------------------------------</font></div>
<div><font color="#000000">1) This SPK file will replace use of
de403.bsp as the source of precision lunar orientation information for
the lunar Principal Axes (PA) frame. In the near future NAIF will use
de418 to produce the appropriate lunar orientation binary PCK file; it
will replace<font face="Lucida Grande" size="-4">
moon_pa_de403_1950-2198.bpc</font></font><font
color="#000000"><b>.</b></font></div>
<div><font color="#000000"><b><br></b></font></div>
<div><font color="#000000">2) As needed NAIF will also prepare the
allied new lunar frames kernels (FKs) replacing the existing lunar
FKs:</font></div>
<div><font color="#000000"><br></font></div>
<div><font color="#000000"> moon_060721.tf</font></div>
<div><font color="#000000"> moon_assoc_pa.tf</font></div>
<div><font color="#000000"> moon_assoc_me.tf</font></div>
<div><font color="#000000"><br></font></div>
<div><font color="#000000">3) NAIF will prepare a new masses PCK file
to replace the existing de-403-masses.tpc.</font></div>
<div><font color="#000000"><br></font></div>
<div><font color="#000000"><br></font></div>
<div><font color="#000000">All of the above will be announced using
"spice_announce" once the items are available.</font></div>
</body>
</html>