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Home / Compressed Ascii JPL Ephemerides
Name Modified Size Downloads / Week Status
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Totals: 21 Items   2.0 GB 23
README.release 2013-02-05 5.4 kB 11 weekly downloads
de424.tar 2013-02-04 43.9 MB 11 weekly downloads
de423.tar 2013-02-04 39.8 MB 11 weekly downloads
de422_old.tar 2013-02-04 595.3 MB 22 weekly downloads
de422.tar 2013-02-04 592.3 MB 11 weekly downloads
de421.tar 2013-02-04 14.9 MB 11 weekly downloads
de406.tar 2013-02-04 211.1 MB 11 weekly downloads
de405.tar 2013-02-04 66.0 MB 22 weekly downloads
de200.tar 2013-02-04 50.6 MB 11 weekly downloads
de102_old.tar 2013-02-04 191.5 MB 11 weekly downloads
de102.tar 2013-02-04 165.5 MB 11 weekly downloads
de423.tar.asc 2013-02-04 490 Bytes 11 weekly downloads
de424.tar.asc 2013-02-04 490 Bytes 22 weekly downloads
de422_old.tar.asc 2013-02-04 490 Bytes 11 weekly downloads
de406.tar.asc 2013-02-04 490 Bytes 11 weekly downloads
de421.tar.asc 2013-02-04 490 Bytes 11 weekly downloads
de422.tar.asc 2013-02-04 490 Bytes 11 weekly downloads
de102.tar.asc 2013-02-04 490 Bytes 11 weekly downloads
de102_old.tar.asc 2013-02-04 490 Bytes 0
de200.tar.asc 2013-02-04 490 Bytes 11 weekly downloads
de405.tar.asc 2013-02-04 490 Bytes 11 weekly downloads
These JPL planetary ephemerides in compressed ascii form have been released as a public service by the Time Ephemerides Project for those wanting to manipulate or interpolate JPL ephemerides using the ephcom software without paying the substantially larger bandwidth costs of the uncompressed ascii form of JPL planetary ephemerides that are available from JPL. This update of the previous file release adds de421 (the short JPL planetary ephemeris recommended for general use according to JPL notes) and de424 to the previous results. I have also taken this opportunity to repackage the older compressed ascii JPL ephemeris data. I now use an uncompressed tarball (since the included files are already compressed) with read-only permissions of files within the tarball. I also drop the previous extra top-level directory of the tarball. This repackaging has not changed the compressed ascii JPL planetary ephemeris data contained within the package. These data (assumed to be in the public domain) were (except for de102_old, see below) downloaded from ftp://ssd.jpl.nasa.gov/pub/eph/planets/ascii and then compressed using, e.g., export EPHEMERIS=de421 # Generic instructions for given EPHEMERIS mkdir $EPHEMERIS cd $EPHEMERIS wget "ftp://ssd.jpl.nasa.gov/pub/eph/planets/ascii/$EPHEMERIS/*" bzip2 asc* md5sum * >md5sum.out # Make all files read-only within directory chmod 444 * cd .. tar cf $EPHEMERIS.tar $EPHEMERIS gpg --default-key BB159E92 --detach-sign --armor $EPHEMERIS.tar gpg --verify $EPHEMERIS.tar.asc The de102, de200, de405, de406, de422 (renamed to de_422_old, see below), and de423 data were downloaded from the JPL ftp site as of July 2011 while the de421 and de424 data were downloaded from that site as of January 2013. Subsequent to the initial download, I discovered that July 2011 version of de422 (renamed now as de422_old) had Julian dates which had some minor numerical noise in them rather than the expected exact half integer. The ephcom software deals with this issue by correcting all such Julian dates read from the binary form of the ephemeris to be exactly half integral. This change constrains the time range of each block of data from the binary ephemeris to be an exact integer number of days and that greatly simplifies the subsequent ephcom logic. After I brought this Julian day noise for de422_old to Bill Folkner's attention, he reissued de422 on 2011-08-04 with exact half-integral Julian dates and slightly more severe rounding of coefficients (1 unit in the last place). I designate this version (which I downloaded on 2011-08-07) simply as de422 and the previously downloaded version of de422 as de422_old. In addition, in the year 2000 I received an ascii copy of de102 from Myles Standish on CD which I have copied here (in bzip2 form) as de102_old. These data have a different disk organization (blocks of 100 years rather than 300 years), are rounded to 19 (!) significant digits rather than 16 significant digits, and include a file containing an additional 10 years prior to the start of de102. de102_old and de102 also have different pseudo-random epochs of test data in testpo.102. Despite these differences, I doubt there is anything substantially different between these two forms representing the same JPL ephemeris calculation, and similarly for de422_old versus de422. Nevertheless, I include de102_old and de422_old here so that hypothesis of negligible differences with de102 and de422 can be tested. Note that de102, de406 and de422 are the only long ephemerides still being distributed by JPL. I have also collected here de200 and de405 (well-known reliable short ephemerides that in their era were the basis of the Astronomical Almanac calculations.) Finally, I have also collected here the most recent short ephemerides, de421, de423, and de424. Therefore, I believe this collection of JPL ephemerides will be sufficient for most ephcom users' ephemeris needs. However, I am open to copying more ephemerides from JPL and adding them to this collection in convenient compressed form if such a request is made by an ephcom user. For a full descriptions of all ephemerides currently being distributed by JPL, see ftp://ssd.jpl.nasa.gov/pub/eph/planets/README.txt. NOTES: There is no need to uncompress the ephemeris data collected here after download since that would substantially increase disk requirements. Instead, the ephcom_concatenate script that is released as part of the ephcom software package automatically recognizes bzip2 or gzip compressed forms or the uncompressed form of the JPL ascii planetary ephemerides and for the compressed forms uncompresses them on the fly as needed. The script result is the uncompressed form of JPL ascii ephemeris concatenated in the correct order is sent to stdout. Those data are subsequently used by ephcom_asc2eph to generate the corresponding binary form of the JPL ephemeris, see, e.g., the binary_de423 target configured by the ephcom build and test system. If a user so prefers, the ephcom_concatenate script and therefore the rest of the ephcom software stack should also work using the original uncompressed form of JPL ascii ephemerides downloaded directly from ftp://ssd.jpl.nasa.gov/pub/eph/planets/ascii. But the bandwidth and disk storage costs will be higher than for the compressed form of the same data collected here.
Source: README.release, updated 2013-02-05