Index Page tipbod_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 tipbod_c ( ConstSpiceChar  * ref,
                       SpiceInt          body,
                       SpiceDouble       et,
                       SpiceDouble       tipm[3][3] )

#### Abstract

       Return a 3x3 matrix that transforms positions in inertial
       coordinates to positions in body-equator-and-prime-meridian
       coordinates.

#### Required_Reading

       PCK
       NAIF_IDS
       ROTATION
       TIME

#### Keywords

       TRANSFORMATION
       ROTATION

#### Brief_I/O

       VARIABLE  I/O  DESCRIPTION
       --------  ---  --------------------------------------------------
       ref        I   ID of inertial reference frame to transform from.
       body       I   ID code of body.
       et         I   Epoch of transformation.
       tipm       O   Transformation (position), inertial to prime
                      meridian.

#### Detailed_Input

       ref         is the NAIF name for an inertial reference frame.
                   Acceptable names include:

                     Name       Description
                     --------   --------------------------------
                     "J2000"    Earth mean equator, dynamical
                                equinox of J2000

                     "B1950"    Earth mean equator, dynamical
                                equinox of B1950

                     "FK4"      Fundamental Catalog (4)

                     "DE-118"   JPL Developmental Ephemeris (118)

                     "DE-96"    JPL Developmental Ephemeris ( 96)

                     "DE-102"   JPL Developmental Ephemeris (102)

                     "DE-108"   JPL Developmental Ephemeris (108)

                     "DE-111"   JPL Developmental Ephemeris (111)

                     "DE-114"   JPL Developmental Ephemeris (114)

                     "DE-122"   JPL Developmental Ephemeris (122)

                     "DE-125"   JPL Developmental Ephemeris (125)

                     "DE-130"   JPL Developmental Ephemeris (130)

                     "GALACTIC" Galactic System II

                     "DE-200"   JPL Developmental Ephemeris (200)

                     "DE-202"   JPL Developmental Ephemeris (202)

                   (See the routine CHGIRF for a full list of names.)

                   The output tipm will give the transformation
                   from this frame to the bodyfixed frame specified by
                   body at the epoch specified by et.

       body        is the integer ID code of the body for which the
                   position transformation matrix is requested. Bodies
                   are numbered according to the standard NAIF
                   numbering scheme.  The numbering scheme is
                   explained in the NAIF_IDS required reading file.

       et          is the epoch at which the position transformation
                   matrix is requested. (This is typically the
                   epoch of observation minus the one-way light time
                   from the observer to the body at the epoch of
                   observation.)

#### Detailed_Output

       tipm        is a 3x3 coordinate transformation matrix.  It is
                   used to transform positions from inertial coordinates to
                   body fixed (also called equator and prime meridian)
                   coordinates.

                   Given a position P in the inertial reference frame
                   specified by ref, the corresponding bodyfixed
                   position is given by the matrix vector product

                      tipm * s

                   The X axis of the PM system is directed to the
                   intersection of the equator and prime meridian.
                   The Z axis points along  the spin axis and points
                   towards the same side of the invariable plane of
                   the solar system as does earth's north pole.

#### Parameters

       None.

#### Exceptions

       1) If the kernel pool does not contain all of the data required
          for computing the transformation matrix, tipm, the error
          SPICE(INSUFFICIENTANGLES) is signalled.

       2) If the reference frame ref is not recognized, a routine
          called by tipbod_c will diagnose the condition and signal an
          error.

       3) If the code body is not recognized, the error is diagnosed by a
          routine called by tipbod_c.

       4) If the input string pointer is null, the error
          SPICE(NULLPOINTER) will be signaled.

       5) If the input string has length zero, the error
          SPICE(EMPTYSTRING) will be signaled.

#### Files

        None.

#### Particulars

       tipbod_c takes PCK information as input, either in the form of a
       binary or text PCK file.  If the data required to compute tipm are
       available in a binary PCK, these data will take precedence over data
       from a text PCK.  If there are multiple binary PCKs containing data
       from which tipm can be computed, the last loaded PCK takes
       precedence.  If binary PCK data are available for the requested body
       and time, the Euler angles giving the body's orientation are
       evaluated, and the transformation matrix tipm is calculated from
       them.  Using the Euler angles PHI, DELTA and W we compute

          TIPM = [W] [DELTA] [PHI]
                    3       1     3

       If no appropriate binary PCK files have been loaded, text PCK data
       are used.  Here information is found as RA, DEC and W (with the
       possible addition of nutation and libration terms for satellites).
       Again, the Euler angles are found, and the transformation matrix is
       calculated from them.  The transformation from inertial to
       bodyfixed coordinates is represented as:

          TIPM = [W] [HALFPI-DEC] [RA+HALFPI]
                    3            1           3

       These Euler angles RA, DEC and W are related to PHI, DELTA and W
       by the equations

          RA  = PHI  - pi/2
          DEC = pi/2 - DELTA
          W   = W

       In the text file, RA, DEC, and W are defined as follows:

                                       2      ____
                                  RA2*t       \
          RA  = RA0  + RA1*t/T  + ------   +  /     a  sin theta
                                     2        ----   i          i
                                    T           i

                                        2     ____
                                  DEC2*t      \
          DEC = DEC0 + DEC1*t/T + -------  +  /    d  cos theta
                                      2       ----  i          i
                                     T          i

                                      2      ____
                                  W2*t       \
          W   = W0   + W1*t/d   + -----   +  /     w  sin theta
                                     2       ----   i          i
                                    d          i

       where:

          d = seconds/day

          T = seconds/Julian century

          a , d , and w  arrays apply to satellites only.
           i   i       i

          theta  = THETA0(i) + THETA1(i)*t/T are specific to each
               i

          planet.

       These angles---typically nodal rates---vary in number and
       definition from one planetary system to the next.

#### Examples

       Note that the items necessary to compute the Euler angles
       must have been loaded into the kernel pool (by one or more
       previous calls to furnsh_c).  The Euler angles are typically
       stored in the P_constants kernel file that comes with
       CSPICE.

       1)  In the following code fragment, tipbod_c is used to transform
           a position in J2000 inertial coordinates to a position in
           bodyfixed coordinates.

           The 3-vector postn represents the inertial position
           of an object with respect to the center of the
           body at time et.

              #include "SpiceUsr.h"
                    .
                    .
                    .
              /.
              First load the kernel pool.
              ./
              furnsh_c ( "PLANETARY_CONSTANTS.KER" );

              /.
              Next get the transformation.
              ./
              tipbod_c ( "J2000", body, et, tipm );

              /.
              Convert position to bodyfixed coordinates.
              ./
              mxv_c ( tipm, postn, bfxpos );

#### Restrictions

       The kernel pool must be loaded with the appropriate
       coefficients (from the P_constants kernel or binary PCK file)
       prior to calling this routine.

#### Literature_References

       None.

#### Author_and_Institution

       N.J. Bachman   (JPL)
       W.L. Taber     (JPL)
       K.S. Zukor     (JPL)

#### Version

       -CSPICE Version 1.0.2, 14-AUG-2006   (EDW)

          Replace mention of ldpool_c with furnsh_c.

       -CSPICE Version 1.0.1, 13-APR-2000 (NJB)

          Made some minor updates and corrections in the code example.

       -CSPICE Version 1.0.0, 08-FEB-1998 (NJB)

          Based on SPICELIB Version 1.0.3, 10-MAR-1994 (KSZ).

#### Index_Entries

       transformation from inertial position to bodyfixed

#### Link to routine tipbod_c source file tipbod_c.c

    Wed Apr  5 17:54:45 2017