Deep Impact/EPOXI CK files.
===========================================================================

   This ``aareadme.txt'' file describes contents of the kernels/ck
   directory of the Deep Impact/EPOXI SPICE data server. It was last
   modified on March 12, 2008. Contact Chuck Acton (818-354-3869,
   Chuck.Acton@jpl.nasa.gov) or Boris Semenov (818-354-8136,
   Boris.Semenov@jpl.nasa.gov) if you have any questions regarding this
   data.


EPOXI C-kernels Contained on This Directory
===========================================

   The following EPOXI CK files are provided in this directory (only
   the leading portion of the file name is shown; the extension of all
   CK file names is ".bc"):

      dif_sc_YYYY-MM-DD          daily DIF/EPOXI reconstructed
                                 spacecraft orientation CK file based
                                 on the low rate real-time and CFDP
                                 attitude telemetry

      dif_sc_YYMMDD_YYMMDD       merged DIF/EPOXI reconstructed
                                 spacecraft orientation CK file based
                                 on the low rate real-time and CFDP
                                 attitude telemetry


Deep Impact C-kernels Contained on This Directory
=================================================
 
   The following Deep Impact CK files are provided in this directory
   (only the leading portion of the file name is shown; the extension
   of all CK file names is ".bc"):

      dif_sc_050112_050809       Deep Impact Flyby (DIF) spacecraft
                                 orientation CK file based on the low
                                 rate real-time attitude telemetry and
                                 covering the whole primary mission.

      dif_sc_050225_highrate     DIF spacecraft orientation CKs based 
      dif_sc_050704_highrate     on the high-rate recorded attitude 
                                 telemetry covering two short windows 
                                 when such telemetry was produced -- 
                                 first at the beginning of the mission
                                 and second for about one hour around 
                                 the closest encounter.

      dif_hga_050117_050801_vch  DIF High Gain Antenna (HGA) orientation
      dif_hga_050118_050801_bch  CK files produced from channelized 
                                 telemetry, each covering the whole 
                                 primary mission. The "vch" file is 
                                 based on the "measured" gimbal angles
                                 while the "bch" file is based on the 
                                 commanded channels.

      dii_sc_050112_050703       Deep Impact Impactor (DII) spacecraft
      dii_sc_050703_050704       orientation CK files. The first of the
                                 two files provides coverage for the
                                 whole period when DII was attached to
                                 DIF; attitude is this file is provided
                                 as a fixed offset of DII frame
                                 relative to the DIF frame derived from
                                 the in-flight calibration data. The
                                 second file provides DII orientation
                                 from separation until the impact; this
                                 orientation is based on DII attitude
                                 telemetry data.

   These CK files should be loaded into a user application in the
   following order to guarantee that, when available, the most accurate
   attitude data is returned to calling application ahead of the less 
   accurate data:

      dif_hga_050118_050801_bch.bc
      dif_hga_050117_050801_vch.bc

      dif_sc_050112_050809.bc
      dif_sc_050225_highrate.bc
      dif_sc_050704_highrate.bc

      dii_sc_050112_050703.bc
      dii_sc_050703_050704.bc


EPOXI CK File Naming Scheme
===========================

   The EPOXI CK files provided in this directory are named according to
   the following scheme:

      TBD


Deep Impact CK File Naming Scheme
=================================

   The Deep Impact CK files provided in this directory are named
   according to the following scheme:

      sc_struct_YYMMDD[_yymmdd][_ident][_vX]

   where:

      sc        is the name of the spacecraft: "dif" or "dii";

      struct    is the name of the spacecraft structure: "sc" for 
                spacecraft itself; "hga" for the High Gain Antenna;

      YYMMDD    is the file coverage start date;

      yymmdd    is the file coverage stop date (optional; provided only
                if the file covers more than one day);

      ident     is a token further identifying the data in the file
                (optional). Examples: "highrate" for high-rate
                data, "bch" for "B"-channel based attitude, etc.

      vX        is the file version number (optional; if omitted,
                the file version is "0").

   The file with the highest version number supersedes all files with
   the same name but earlier version numbers.


Kernel File Details 
===================

   The most detailed description of the data in a binary CK file is
   provided in metadata included inside the comment area of the file.
   This information can be viewed using the utility programs COMMNT and
   SPACIT included in the NAIF Toolkit.