Procedure

     SPKR05 ( Read SPK record from segment, type 5 )

     SUBROUTINE SPKR05 ( HANDLE, DESCR, ET, RECORD )

Abstract

     Read a single SPK data record from a segment of type 5
     ( two body propagation between discrete state vectors ).

Required_Reading

     SPK

Keywords

     EPHEMERIS

Declarations

     IMPLICIT NONE

     INTEGER               HANDLE
     DOUBLE PRECISION      DESCR    ( 5 )
     DOUBLE PRECISION      ET
     DOUBLE PRECISION      RECORD   ( * )

Brief_I/O

     VARIABLE  I/O  DESCRIPTION
     --------  ---  --------------------------------------------------
     HANDLE     I   File handle.
     DESCR      I   Segment descriptor.
     ET         I   Target epoch.
     RECORD     O   Data record.

Detailed_Input

     HANDLE,
     DESCR    are the file handle and segment descriptor for
              the type 05 SPK segment to be read.

     ET       is a target epoch, specified as ephemeris seconds past
              J2000, for which a data record from the segment is
              required.

Detailed_Output

     RECORD   is a logical record from the specified segment which,
              when evaluated at epoch ET, will give the state
              (position and velocity) of some body, relative
              to some center, in some inertial reference frame.

              The structure of RECORD is:

                  RECORD(1)
                     .            state of the body at epoch 1.
                     .
                     .
                  RECORD(6)

                  RECORD(7)
                     .
                     .            state of the body at epoch 2.
                     .
                  RECORD(12)
                  RECORD(13)      epoch 1 in seconds past 2000.
                  RECORD(14)      epoch 2 in seconds past 2000.
                  RECORD(15)      GM for the center of motion.


              Epoch 1 and epoch 2 are the times in the segment that
              bracket ET. If ET is less than the first time in the
              segment then both epochs 1 and 2 are equal to the
              first time. And if ET is greater than the last time
              then, epochs 1 and 2 are set equal to this last time.

Parameters

     None.

Exceptions

     1)  If the segment specified by DESCR is not of data type 05,
         the error SPICE(WRONGSPKTYPE) is signaled.

     2)  No error is signaled if ET is outside the time bounds of
         the segment. The output RECORD will contain epochs and the
         associated states which satisfy the rules stated above.

Files

     See argument HANDLE.

Particulars

     This routine reads the segment specified by DESCR from the SPK
     file attached to HANDLE to locate the two epochs in the segment
     that bracket the input ET. It then returns a logical record which
     contains these times and their associated states, and also the
     mass of the center of motion. The routine makes explicit use of
     the structure of the type 05 data segment to locate this data.

     See the section of the SPK Required Reading on data type 05 for
     a description of the structure of a type 05 segment.

Examples

     The data returned by the SPKRnn routine is in its rawest form,
     taken directly from the segment. As such, it will be meaningless
     to a user unless he/she understands the structure of the data type
     completely. Given that understanding, however, the SPKRnn
     routines might be used to "dump" and check segment data for a
     particular epoch.


     C
     C     Get a segment applicable to a specified body and epoch.
     C
           CALL SPKSFS ( BODY, ET, HANDLE, DESCR, IDENT, FOUND )

           IF ( FOUND ) THEN

     C
     C        Look at parts of the descriptor.
     C
              CALL DAFUS ( DESCR, 2, 6, DCD, ICD )
              CENTER = ICD( 2 )
              REF    = ICD( 3 )
              TYPE   = ICD( 4 )

              IF ( TYPE .EQ. 05 ) THEN

                 CALL SPKR05 ( HANDLE, DESCR, ET, RECORD )
                     .
                     .  Look at the RECORD data.
                     .
              END IF

           END IF

Restrictions

     None.

Literature_References

     None.

Author_and_Institution

     J. Diaz del Rio    (ODC Space)
     J.M. Lynch         (JPL)
     W.L. Taber         (JPL)
     I.M. Underwood     (JPL)
     E.D. Wright        (JPL)

Version

    SPICELIB Version 1.1.1, 12-AUG-2021 (JDR)

        Edited the header to comply with NAIF standard.

    SPICELIB Version 1.1.0, 07-SEP-2001 (EDW)

        Replaced DAFRDA call with DAFGDA.
        Added IMPLICIT NONE.

    SPICELIB Version 1.0.0, 01-APR-1992 (JML) (WLT) (IMU)