CL_fr_convert

Description

• Converts position and (optionally) velocity vectors relative to "frame1" to position and (optionally) velocity vectors relative to "frame2".

  The jacobian of the transformation is optionally computed.

  The available frames are :

  

  In addition, 2 other frames (or names) are defined: ECI and ECF.

  See Reference frames for more details on the definition of reference frames.

• Notes:

  - The date "cjd" is relative to the TREF time scale.

  - Which optional arguments need to be supplied depends on the frame transformation. See the frame transformation diagram for more details.

  - The frame names are case sensitive.

  - If only the position needs to be converted, vel1 can be omitted or set to []. (vel2 will then be set to []).

Parameters

cjd:

Modified Julian date from 1950.0 (TREF time scale) (1xN or 1x1)

frame1:

(string) Initial frame (1x1)

frame2:

(string) Final frame (1x1)

pos1:

Position vector in initial frame [m] (3xN or 3x1)

vel1:

(optional) Velocity vector in initial frame [m/s] (3xN or 3x1)

ut1_tref:

(optional) UT1-TREF [seconds]. Default is %CL_UT1_TREF (1xN or 1x1)

tt_tref:

(optional) TT-TREF [seconds]. Default is %CL_TT_TREF. (1xN or 1x1)

xp, yp:

(optional) Position of the pole in ITRS [rad] (1xN or 1x1)

dX, dY:

(optional) Corrections to CIP coordinates [rad] (1xN or 1x1)

use_interp:

(optional, boolean) %t to use interpolation when computing CIP coordinates. Default is %t. (1x1)

pos2:

Position vector in final frame [m] (3xN)

vel2:

(optional) Velocity vector in final frame [m/s] (3xN)

jacob:

(optional) Jacobian of the transformation: (pos1,vel1) to (pos2,vel2) (6x6xN)

Authors

• CNES - DCT/SB

Examples

// Conversion of position from Veis to EME2000 (All optional arguments to default) pos1 = [3500.e3; 2500.e3; 5800.e3]; cjd_tref = 21010; pos_EME2000 = CL_fr_convert("Veis", "EME2000", cjd_tref, pos1); // Conversion of position and velocity from GCRS to TIRS pos_GCRS = [3500.e3; 2500.e3; 5800.e3]; vel_GCRS = [1.e3; 3.e3; 7.e3] ; cjd_tref = [21010, 21011]; [pos_TIRS,vel_TIRS,jacob] = CL_fr_convert("GCRS","TIRS",cjd_tref,pos_GCRS,vel_GCRS,ut1_tref=-0.2);