MEX PCK Files ============= This "aareadme.txt" file describes the contents of the kernels/pck directory of the MEX SPICE data server. It also provides the file naming conventions used for the MEX PCK kernels, and it provides identification of the most current version of each kind of PCK file. PCK files in this directory are either binary or text files. Text files are created manually with the information from mainly the 2000 IAU Report. Binary files are created from the information contained in the EOP files provided by IERS. The most detailed description of the data in a text PCK file is provided in metadata included inside the description area of the file. This information can be viewed using any text editor program. For a binary PCK kernel, this information can be viewed using utility programs COMMNT and SPACIT included into the NAIF Toolkit. At least a basic knowledge of the SPICE system is needed in order to use these kernels. The SPICE toolkit provides versions in Fortran (SPICELIB), C (CSPICE), IDL (icy) and Matlab (mice), and the user can choose any one that suits him/her. The SPICELIB routine FURNSH, CSPICE function furnsh_c, and icy and mice routine cspice_furnsh load a kernel file into the kernel pool as shown below. CALL FURNSH ( 'kernel_name' ) furnsh_c ( "kernel_name" ); cspice_furnsh, 'kernel_name' cspice_furnsh( 'kernel_name' ) In the case when two or more files contain data overlapping in time for a given object, for binary kernels, the file loaded last takes precedence. If two (or more) text kernels assign value(s) using the '=' operator to identical keywords, the data value(s) associated with the last loaded occurrence of the keyword are used -all earlier values have been replaced with the last loaded value(s). All binary PCK files (*.BPC) contained in this directory are unix binary files. These may be used as is (without format conversion) in a non-unix environment by using any recent version of the SPICE Toolkit (Version N0052 or later). All text PCK files (*.TPC) contained in this directory are unix text files. These may be used in a non-compatible text environment by using the ASCII mode of FTP to port the files. Contact ESA SPICE Team esa_spice@sciops.esa.int , or Jose Luis Vazquez jlvazquez@sciops.esa.int if you have any questions. References ========== 1. PCK Reading (NAIF Document). 2. NAIF IDs Required Reading (NAIF Document). All the NAIF Documents are available at the NAIF web: http://naif.jpl.nasa.gov Mars Express PCK Directory Structure ==================================== aareadme.txt This file. former_versions Subdirectory that contains obsolete versions of the PCK files that have been updated in the Current PCK Kernel Set. EARTH_[sdat]_[edat]_[pdat].BPC PCK file containing the orientation of the Earth as a function of time for the interval from [sdat] until [edat]. From [pdat] the information contained in the file corresponds to predicted data. The rotational effects included are precession, nutation, rotation through true siderial time, polar motion and nutation corrections. MARS_IAU2000_Vx.TCP PCK file containing the radii and orientation constants for Mars and its natural satellites DE403-MASSES.TPC PCK file containing the masses for the sun and planetary barycenters. These masses are given as ratios to of Solar GM to barycenter GM. PCK00008.TPC PCK file containing the size, shape, radii and orientation constants for planets, satellites, Sun and some asteroids. ------------------- This file was last modified on March 4th, 2009. (J. Vazquez)