General information about SPICE PC-kernels ========================================== In the SPICE system, the PCK kernel provides orientation and ellipsoidal shape information pertaining to extended solar system bodies such as the Sun, the planets, the natural satellites of the planets, comets, and asteroids. The most recent generic PC kernel file based on the latest published IAU report can always be obtained from NAIF/JPL. The purpose of the PCK kernels and associated software is to provide SPICE users with a convenient mechanism for supplying planetary physical constants to application programs. SPICE PCK routines are able to read files conforming to the PCK format and return to a calling application program both the data contained in such files and a small number of commonly used numeric quantities derived from the kernel data. For information on the SPICE Toolkit and/or how to obtain it, please consult SPICE_INST.CAT and SOFT.CAT. Refer to the PCK.REQ document provided with the Toolkit to get more information on how to access PC-kernel data. ROSETTA PCK Files ================= This file describes the contents of the DATA/PCK directory of the ROSETTA SPICE data set. PCK files in this directory are either binary or text files. The generic text PCK files are created manually with information from IAU Reports. Binary files are created using an automated process run by NAIF from the information contained in JPL's EOP files based on the IERS Earth rotation data. All binary PCK files (*.BPC) contained in this directory are little-endian (LTL-IEEE) binary files. All text PCK files (*.TPC) contained in this directory are UNIX text files with lines terminated by only. Current PC-Kernels Contained in this Data Set ============================================= The following PCK-kernels are provided in this data set: Rosetta Mission Target Text PCKs: ROS_CG_RAD_V10.TPC Contains the "Cheops reference frame" radii values for 67P/C-G. This file should be loaded when using DSKs in order to make use of all DSK API capabilities. ROS_CG_ROT_1408_1409_V10.TPC Contains the "Cheops reference frame" rotation constants for 67P/C-G for August-September 2014. This PCK is included only for the record because its data is applicable only to the 2014-08-01 to 2014-09-30 range and must not be used for any other times. 67P/C-G CKs providing orientation of the 67P/C-G_CK frame must be used instead of this PCK to get orientation of the comet. ROS_CGS_RSOC_V01.TPC Contains the preliminary size/shape and orientation constants for 67P/C-G. This file is obsolete and must not be used. ROS_LUTETIA_RSOC_V01.TPC ROS_LUTETIA_RSOC_V03.TPC Contain the size/shape and orientation constants for asteroid 21 Lutetia, the RSOC solution. The file with the latest version supersedes all previous versions. The latest PCK in this set is the preferred kernel for processing the Lutetia flyby data. ROS_LUTETIA_LC1_V02.TPC ROS_LUTETIA_LC2_V02.TPC Contain the size/shape and orientation constants for asteroid 21 Lutetia, based on light curve pole solutions. The file with the latest version supersedes all previous versions. ROS_LUTETIA_R1_V02.TPC ROS_LUTETIA_R2_V02.TPC Contain the size/shape and orientation constants for asteroid 21 Lutetia, based on radar pole solutions. The file with the latest version supersedes all previous versions. ROS_STEINS_V03.TPC ROS_STEINS_V04.TPC ROS_STEINS_V05.TPC Contain the size/shape and orientation constants for asteroid 2867 Steins. The file with the latest version supersedes all previous versions. Generic Text PCKs: PCK00010.TPC Contains the size/shape and orientation constants for planets, satellites, Sun and some asteroids from the IAU 2009 report. PCK00008.TPC Contains the size/shape and orientation constants for planets, satellites, Sun and some asteroids from the IAU 2000 report. This PCK is superseded by PCK00010.TPC. DE403_MASSES.TPC Contains the masses for the sun, planets, satellites and planetary barycenters. These masses are given as ratios of Solar GM to barycenter GM. High-precision Earth Orientation Binary PCKs: EARTH_000101_070916_070625.BPC EARTH_000101_100428_100204.BPC EARTH_000101_110111_101020.BPC EARTH_000101_120117_111026.BPC EARTH_000101_160131_151109.BPC EARTH_000101_170227_161206.BPC Contain the orientation of the Earth as a function of time for the interval given by the first and the third dates in the file name. Starting from the second date in the name 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. Kernel File Details =================== 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. The most detailed description of the data in a binary PCK file is provided in metadata included inside the comment area of the file. This information can be viewed using utility programs 'commnt' and 'spacit' included in the SPICE 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), Matlab (Mice), and Java (JNISpice) and the user can choose any one that suits him/her. The SPICE routine FURNSH can be used to load a kernel file into a SPICE-based application to make kernel data usable with SPICE APIs. In the case when two or more binary PCK files contain data overlapping in time for a given object 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).