General information about SPICE SCL-kernels
===========================================

   In the SPICE system, the Spacecraft Clock (or SCL) -kernel contains
   information required to perform a mapping between Ephemeris time
   (ET, also called Barycentric Dynamic Time, or TDB) and spacecraft
   on-board time (SCLK).

   The spacecraft clock coefficient information contained in an SCLK
   file can be manipulated by a collection of subroutines to provide a
   transformation between Ephemeris and spacecraft on-board times.
   These subroutines are part of the SPICE library, the major component
   of the SPICE Toolkit. The routines needed are integrated into a
   user's application programs. For information on the SPICE Toolkit
   and/or how to obtain it, please consult SPICE_INST.CAT and SOFT.CAT.

   Refer to the SCLK.REQ document provided with the Toolkit to get more
   information about conversion between ET and spacecraft clock times.


ROSETTA SCLK Files
==================

   This file describes the contents of the DATA/SCLK directory of the
   ROSETTA SPICE data set.

   SCLK files are created from the information contained in ESOC's
   DDID Time Correlation Packets.

   All SCLK files (*.TSC) contained in this directory are UNIX text
   files with lines terminated by <LF> only.


ROSETTA SCL-Kernels Contained in this Data Set
==============================================

   The following ROSETTA SCL-kernels are provided in this data set:

      ROS_061208_STEP.TSC
      ROS_091210_STEP.TSC
      ROS_100617_STEP.TSC
      ROS_110405_STEP.TSC
      ROS_150908_STEP.TSC
      ROS_160929_STEP.TSC    These files are SPICE spacecraft clock
                             (SCLK) kernels containing information
                             required for Rosetta spacecraft on-board
                             clock to UTC conversion. They provide the
                             same time information as the Time
                             Correlation packets released via DDS, with
                             the exception of 60 seconds before the
                             starting time of each packet,during which
                             the clock rate was sightly adjusted to make
                             the correlation function continuous. The
                             file with the latest release date shown in
                             the name supersedes all earlier files.

      LANDER_170904_STEP.TSC This file is a SPICE spacecraft clock (SCLK)
                             kernel containing information required for
                             Rosetta lander on-board clock to UTC
                             conversion. This file provides the same time
                             information that the Time Correlation
                             packets released via DDS, with the exception
                             of 60 seconds before the starting time of
                             each packet, during which the clock rate was
                             sightly adjusted to make the correlation
                             function continuous.


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

   The most detailed description of the data in an SCLK file is
   provided in metadata included inside the description area of the
   file. This information can be viewed using any text editor program.

   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.

   If two (or more) text SCLK 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).