ephcom-3.0.0 has been released

The ephcom-3.0.0 software package that gives users convenient access to planetary and time ephemerides has just been released. New features of this release compared to ephcom-2.0.2 include the following: a convenient new high-level C API; new Fortran 95 and Python interfaces to that high-level API; an order of magnitude increase in speed; the ability to access INPOP ephemerides (in addition to the previously accessible JPL ephemerides); the ability to access time ephemerides; and the ability to access both planetary and time binary ephemerides in any endian order. Planetary ephemerides represent mankind's best knowledge of the positions and velocities of all major bodies of the solar system over centuries (short ephemerides) and millennia (long ephemerides). Time ephemerides are computed from planetary ephemerides and represent mankind's best knowledge of the general relativistic corrections that must be made to clocks that are located near some reference point within the solar system (e.g., some point near the Earth). Such clock corrections are required, for example, to correctly predict the independent time variable of planetary ephemerides from TT (terrestrial time).

The ephcom software allows the user to manipulate (e.g., convert from compressed or uncompressed ascii form to binary form) as well as interpolate (i.e., provide results at a given time from the binary form of ephemerides) most published planetary and time ephemerides in a well-documented (see http://timeephem.sourceforge.net/documentation.php\) way. The JPL group have published planetary ephemerides in binary and uncompressed ascii forms at ftp://ssd.jpl.nasa.gov/pub/eph/planets/. See also http://sourceforge.net/projects/timeephem/files/Compressed%20Ascii%20JPL%20Ephemerides for a convenient compressed ascii version of these ephemerides that has been released as a companion to the ephcom software. All these representations of the JPL work are accessible to ephcom. The INPOP group have published both planetary and time ephemerides at http://www.imcce.fr/inpop/. The INPOP binary planetary ephemerides labelled "Binary files compatible with the JPL DExxx ephemeris file format" is currently accessible to ephcom, and we have future plans to make the other INPOP formats accessible to ephcom as a convenience to our users. The INPOP time ephemerides are currently only available as part of their ascii files (labelled "Text Files" on the INPOP web site), and the te_gen-2.0.0 software (which is within a day or so of being released as companion software to ephcom-3.0.0) provides a utility to convert those INPOP ascii time ephemerides into an ascii form that can be read by ephcom. Finally, binary and ascii time ephemerides which are directly accessible to ephcom and which have been computed using te_gen-2.0.0 for most of the JPL and INPOP planetary ephemerides should soon be released at http://sourceforge.net/projects/timeephem/files/Time%20Ephemerides as a companion to ephcom-3.0.0.

The ephcom development effort which is part of the Time Ephemerides Project (http://timeephem.sourceforge.net) is a revival of the ephcom-1.0.0 development effort which was last released in May 2004 at ephemeris.com by Paul Hardy. The ephcom-3.0.0 release represents a substantial (370 commits) improvement on ephcom-2.0.2 (also developed as part of the Time Ephemerides Project). The ephcom-3.0.0 software release, which is licensed under the LGPL, may be downloaded from http://sourceforge.net/projects/timeephem/files/ephcom. That same location also gives access to ephcom-3.0.0 release notes and the detailed ChangeLog.

Posted by Alan W. Irwin 2013-01-12

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