;+
; NAME:
;  oc_x2t_rotmat
; PURPOSE: (one line)
;  Return the matrix for rotating J2000 XYZ to target coords
; DESCRIPTION:
;  Return the matrix for rotating J2000 XYZ to target coords
; CATEGORY:
;  Occultations
; CALLING SEQUENCE:
;  R = oc_x2t_rotmat(targ, et)
; INPUTS:
;  targ = target (string or id)
;  et = ephemeris time (TDB seconds after J2000)
; OPTIONAL INPUT PARAMETERS:
;  none
; KEYWORD INPUT PARAMETERS:
;  none
; KEYWORD OUTPUT PARAMETERS:
;  none
; OUTPUTS:
;  R - rotation matrix for rotating an vector 
;      XYZ in J2000 coordinates to
;      xyz in target's coordinate system 
;
;    XYZ are the J2000 rectangular coordinates
;     X = cos(ra_s) cos(dec_s)
;     Y = sin(ra_s) cos(dec_s)
;     Z =     sin(dec_s)
;
;   xyz are defined in terms of the targets pole and central meridian
;     unit vector <x> is on the equator at zero longitude
;     unit vector <y> is on the equator at 90 deg longitude
;     unit vector <z> is toward the North pole, 
;
; COMMON BLOCKS:
;  None
; SIDE EFFECTS:
; RESTRICTIONS:
;  None
; PROCEDURE:
;
;
;  Since r is a rotation matrix, the inverse equals the transpose,
;  and we simply call oc_x2t_rotmat
;  
; USE:
;  The matrix is defined so that
;       xyz_targ = R ## XYZ_j2000     ; XYZ_j2000, xyz_targ column vectors
;  where xyz_targ and XYZ_j2000 are column vectors (Array[1,3]) and ## is the
;  IDL operator for ordinary matrix multiplication (inner product).
;  It is usually more convenient to use XYZ_j2000 and xyz_targ as row vectors
;  (Array[3]).  In this case we have
;       xyz_targ = transpose(R) # XYZ_j2000     ; xyz_targ, XYZ_j2000 row vectors
;
; MODIFICATION HISTORY:
;  2007 Sep 12 Leslie A Young SwRI
;-

function oc_x2t_rotmat, targ, et

    return, transpose(oc_t2x_rotmat(targ, et))

end