

CASSINI CDA Orientation CK File
===========================================================================
 
 
Orientation Data in the File
--------------------------------------------------------
 
     This CK file contains two segments.
 
     The first segment provides the actual orientation of the CASSINI
     CDA articulating frame, ``CASSINI_CDA_ART'' (frame ID -82791),
     with respect to the CDA base frame, ``CASSINI_CDA_BASE'' (frame ID
     -82792).
 
     The second segment provides the fixed orientation of the CASSINI
     CDA instrument frame, ``CASSINI_CDA'' (frame ID -82790), with
     respect to the CDA articulating frame, ``CASSINI_CDA_ART'' (frame
     ID -82791).
 
 
Status
--------------------------------------------------------
 
     The first segment of this file was generated using the CDA
     articulation angle data provided by Nicolas Altobelli and Sascha
     Kempf of the CDA team.
 
     The second segment was using the nominal relationship between the
     CDA frames described in the CASSINI FK.
 
     This file is intended for archiving in CASSINI SPICE PDS data set.
 
 
Pedigree
--------------------------------------------------------
 
     The first segment of this file was generated by converting the CDA
     articulation angle data into CK format using the MSOPCK program.
     To make this file, the UTC-tagged angle data covering the whole
     mission and providing the start time and the final angle for each
     of the instrument moves were augmented additional points
     identifying the end time of the move. The end times were computed
     the nominal commanded instrument rotation rate of 6 degrees per
     minute. After that the data was re-formatted to be acceptable for
     input to and was converted into this CK file using the MSOPCK
     program. The MSOPCK setup file is provided in the Appendix 1 of
     these comments.
 
     The second segment was generated by extracting the subset of data
     for the CK ID -82790 within the time range covered by the first
     segment from the fixed CASSINI instrument CK file "cas_fix_v00.bc"
     prepared by Scott Turner, NAIF/JPL. The description of the fixed
     orientation extracted from this file is provided in the Appendix 2
     of these comments.
 
 
Angular Rates
--------------------------------------------------------
 
     The angular rates stored in this file did not come from the source
     data; instead they were computed from orientation data.
 
 
Approximate Time Coverage
--------------------------------------------------------
 
     The segments contained in this file provide the continuous
     coverage between the start time and stop time given in the header
     of the intervals table given in the Appendix 3 of these comments.
 
 
Usage Note
--------------------------------------------------------
 
     In order to use this file a CASSINI SCLK file, containing
     coefficients mapping CASSINI on-board time to ET, standard LSK
     file, providing UTC to ET mapping, and CASSINI Frame Definitions
     file, containing definitions of the frames orientation of which is
     provided in this CK file, must be loaded into a user program.
 
 
Contacts
--------------------------------------------------------
 
     If you have any question regarding this data contact NAIF at JPL:
 
        Boris V. Semenov
        (818)-354-8136
        Boris.Semenov@jpl.nasa.gov
 
 
Appendix 1: MSOPCK Setup Parameters Used to Generate The First Segment
===========================================================================
 
\begindata
 
   LSK_FILE_NAME           = '/ftp/pub/naif/CASSINI/kernels/lsk/naif0008.tls'
   SCLK_FILE_NAME          = '/ftp/pub/naif/CASSINI/kernels/sclk/cas00105.tsc'
   FRAMES_FILE_NAME        = '/ftp/pub/naif/CASSINI/kernels/fk/cas_v39.tf'
 
   INTERNAL_FILE_NAME      = 'CASSINI CDA Orientation'
 
   CK_TYPE                 = 3
   CK_SEGMENT_ID           = 'CASSINI CDA Orientation'
   INSTRUMENT_ID           = -82791
   REFERENCE_FRAME_NAME    = 'CASSINI_CDA_BASE'
   ANGULAR_RATE_PRESENT    = 'MAKE UP/NO AVERAGING'
 
   INPUT_DATA_TYPE         = 'EULER ANGLES'
   INPUT_TIME_TYPE         = 'UTC'
   EULER_ROTATIONS_ORDER   = ( 'Z' 'Y' 'X' )
   EULER_ANGLE_UNITS       = 'DEGREES'
 
   PRODUCER_ID             = 'Boris Semenov, NAIF/JPL'
 
\begintext
 
 
Appendix 2: Description of the Orientation Stored in the Second Segment
===========================================================================
 
   This segment contains information necessary to connect the frame
   CASSINI_CDA with CASSINI_CDA_ART for epochs from launch until the
   first spacecraft clock rollover. Specifics of segment construction:
 
   The CDA boresight is 135 degrees off of the articulation axis
   (Z-axis in the CASSINI_CDA_ART frame). The CDA boresight is the
   Z-axis in the instrument frame, so construct a frame that performs
   the necessary rotation.
 
           [     ]    [       ]  [     ]  [     ]
           [ ROT ]  = [ 135.0 ]  [ 0.0 ]  [ 0.0 ]
           [     ]    [       ]  [     ]  [     ]
                               X        Y        Z
 
           where [x]  represents the rotation matrix of a given angle
                    i
            x about axis i.
 
   The matrix ROT when left multiplied into vectors in the
   CASSINI_CDA_ART frame yields vectors in the CASSINI_CDA frame.
 
 
Appendix 3: MSOPCK Traceback Information for the First Segment
===========================================================================
 
 
********************************************************************************
RUN-TIME OBTAINED META INFORMATION:
********************************************************************************
 
PRODUCT_CREATION_TIME = 2007-03-09T12:10:30
START_TIME            = 1999-03-25T05:41:22.000
STOP_TIME             = 2007-01-05T06:30:10.000
 
********************************************************************************
INTERPOLATION INTERVALS IN THE FILE SEGMENTS:
********************************************************************************
 
SEG.SUMMARY: ID -82791, COVERG: 1999-03-25T05:41:22.000 2007-01-05T06:30:10.000
--------------------------------------------------------------------------------
      1999-03-25T05:41:22.000    2007-01-05T06:30:10.000
 
 
********************************************************************************
 
