Index Page
cspice_lspcn
A  B  C  D  E  F  G  H  I  J  K  L  M  N  O  P  Q  R  S  T  U  V  W  X 

Abstract
I/O
Examples
Particulars
Required Reading
Version
Index_Entries

Abstract


   CSPICE_LSPCN computes L_s, the planetocentric longitude of the sun,
   as seen from a specified body.

I/O


   Given:

      body     is the name of the central body, typically a planet.

               [1,c1] = size(body); char = class(body)

                  or

               [1,1] = size(body); cell = class(body)

      et       is the epoch at which the longitude of the sun (L_s) is
               to be computed. 'et' is expressed as seconds past J2000
               TDB (Barycentric Dynamical Time).

               [1,n] = size(et); double = class(et)

      abcorr   indicates the aberration corrections to be applied
               when computing the longitude of the sun.

               [1,c2] = size(abcorr); char = class(abcorr)

                  or

               [1,1] = size(abcorr); cell = class(abcorr)

               'abcorr' may be any of the following.

                  'NONE'     Apply no correction.

                  'LT'       Correct the position of the sun,
                             relative to the central body, for
                             planetary (light time) aberration.

                  'LT+S'     Correct the position of the sun,
                             relative to the central body, for
                             planetary and stellar aberrations.

   the call:

      lspcn = cspice_lspcn( body, et, abcorr )

   returns:

      lspcn   the planetocentric longitude of the sun, often called
              "L_s," for the specified body at the specified time.

              [1,n] = size(et); double = class(et)

              The longitude is defined in a right-handed frame whose
              basis vectors are defined as follows:

              - The positive Z direction is given by the instantaneous
                angular velocity vector of the orbit of the body about
                the sun.

              - The positive X direction is that of the cross product
                of the instantaneous north spin axis of the body with
                the positive Z direction.

              - The positive Y direction is Z x X.

              Units are radians; the range is 0 to 2*pi. Longitudes are
              positive to the east.

              'lspcn' returns with the same vectorization measure (N) as 'et'.

Examples


   Any numerical results shown for this example may differ between
   platforms as the results depend on the SPICE kernels used as input
   and the machine specific arithmetic implementation.

      Use the meta-kernel shown below to load the required SPICE
      kernels.

         KPL/MK

         File name: standard.tm

         This meta-kernel is intended to support operation of SPICE
         example programs. The kernels shown here should not be
         assumed to contain adequate or correct versions of data
         required by SPICE-based user applications.

         In order for an application to use this meta-kernel, the
         kernels referenced here must be present in the user's
         current working directory.

         The names and contents of the kernels referenced
         by this meta-kernel are as follows:

            File name                     Contents
            ---------                     --------
            de421.bsp                     Planetary ephemeris
            pck00010.tpc                  Planet orientation and
                                          radii
            naif0011.tls                  Leapseconds

         \begindata

            KERNELS_TO_LOAD = ( 'de421.bsp',
                                'pck00010.tpc',
                                'naif0011.tls'  )

         \begintext

   Example(1):

      Scalar

      cspice_furnsh( 'standard.tm' )

      et = cspice_str2et('21 march 2006')
      lspcn = cspice_lspcn( 'earth', et, 'none' ) * cspice_dpr

   MATLAB outputs:

      lspcn =

          0.2365

   Example(2):

      Vector

      et = cspice_str2et('21 march 2005') + [0:1000000.:10000000.];
      lspcn = cspice_lspcn( 'earth', et, 'none' ) * cspice_dpr

   MATLAB outputs:

      lspcn =

          0.4815   11.9353   23.3193   34.6294   45.8611   57.0476   68.1626
         79.2509   90.3058  101.3366  112.3833

Particulars


   None.

Required Reading


   For important details concerning this module's function, please refer to
   the CSPICE routine lspcn_c.c.

   MICE.REQ
   ABCORR.REQ

Version


   -Mice Version 1.0.0, 10-NOV-2015, EDW (JPL)

      Script rewritten to call CSPICE interface.

   -Mice Version 0.9.0, 23-OCT-2015, EDW (JPL)

      Pure Matlab script.

Index_Entries


   planetocentric longitude of sun
   compute L_s
   compute Ls
   compute L_sub_s


Wed Apr  5 18:00:33 2017