spkssb_c

Index Page spkssb_c
A B C D E F G H I J K L M N O P Q R S T U V W X
Procedure Abstract Required_Reading Keywords Brief_I/O Detailed_Input | Detailed_Output Parameters Exceptions Files Particulars Examples | Restrictions Literature_References Author_and_Institution Version Index_Entries
#### Procedure
       void spkssb_c ( SpiceInt           targ,
                       SpiceDouble        et,
                       ConstSpiceChar   * ref,
                       SpiceDouble        starg[6] )
#### Abstract
       Return the state (position and velocity) of a target body
       relative to the solar system barycenter.
#### Required_Reading
       SPK
#### Keywords
       EPHEMERIS
#### Brief_I/O
       Variable  I/O  Description
       --------  ---  --------------------------------------------------
       targ       I   Target body.
       et         I   Target epoch.
       ref        I   Target reference frame.
       starg      O   State of target.
#### Detailed_Input
       targ        is the standard NAIF ID code for a target body.

       et          is the epoch (ephemeris time) at which the state of the
                   target body is to be computed.

       ref         is the name of the reference frame to which the vectors
                   returned by the routine should be rotated. This may be
                   any frame supported by the CSPICE frame system,
                   including dynamic and other non-inertial frames.
#### Detailed_Output
       starg       contains the position and velocity of the target body,
                   relative to the solar system barycenter, at epoch 'et'.
                   These vectors are rotated into the specified reference
                   frame. Units are always km and km/sec.
#### Parameters
       None.
#### Exceptions
       1) If sufficient information has not been "loaded" via the
          routine spklef_c or the PCK kernel loaders, the problem will
          be diagnosed by a routine in the call tree of this routine.

       2) The error SPICE(EMPTYSTRING) is signaled if the input
          string 'ref' does not contain at least one character, since the
          input string cannot be converted to a Fortran-style string
          in this case.

       3) The error SPICE(NULLPOINTER) is signaled if the input string
          pointer 'ref' is null.
#### Files
       See:  Restrictions.
#### Particulars
       In order to compute the state of one body relative to another,
       the states of the two bodies must be known relative to a third
       body. One simple solution is to use the solar system barycenter
       as the third body.

       Ephemeris data from more than one segment may be required
       to determine the state of a body relative to the barycenter.
       spkssb_c reads as many segments as necessary, from as many
       files as necessary, using files that have been loaded by
       previous calls to spklef_c (load ephemeris file).
#### Examples
       In the following code fragment, spkssb_c is used to display
       the distance from Earth (Body 399) to Mars (body 499) at
       a series of epochs.

          #include <stdio.h>
          #include "SpiceUsr.h"

          #define EARTH   399
          #define MARS    499
              .
              .
              .
          spklef_c ( "DE125.SPK", &handle );
              .
              .
              .

          while ( epoch <= end )
          {
             spkssb_c ( EARTH, epoch, "J2000", searth );
             spkssb_c ( MARS,  epoch, "J2000", smars  );

             printf ( "%f   %22.15e\n", epoch, vdist_c( searth, smars )  );

             epoch += delta;
          }
#### Restrictions
       1) The ephemeris files to be used by spkssb_c must be loaded
          by spklef_c before spkssb_c is called.
#### Literature_References
       NAIF Document 168.0, "S- and P- Kernel (SPK) Specification and
       User's Guide"
#### Author_and_Institution
       N.J. Bachman    (JPL)
       W.L. Taber      (JPL)
       I.M. Underwood  (JPL)
#### Version
       -CSPICE Version 1.0.2, 20-NOV-2004 (NJB)

          Updated description of input argument `ref' to indicate all
          frames supported by CSPICE are allowed.

       -CSPICE Version 1.0.1, 14-OCT-2003 (EDW)

          Various minor corrections to the header.

       -CSPICE Version 1.0.0, 23-JUN-1999 (NJB) (WLT) (IMU)
#### Index_Entries
       state relative to solar system barycenter
#### Link to routine spkssb_c source file spkssb_c.c

    Thu Apr 16 08:59:15 2009