function oc_f2x_rotmat, ra, dec

;+
; NAME:
;  oc_f2x_rotmat
; PURPOSE: (one line)
;  Return the matrix for rotating FGH to XYZ
; DESCRIPTION:
;  Return the matrix for rotating FGH to XYZ
; CATEGORY:
;  Occultations
; CALLING SEQUENCE:
;  R = oc_f2x_rotmat(ra, dec)
; INPUTS:
;  ra - right ascension of occultation star in radians
;  dec - declination of occultation star in radians
; OPTIONAL INPUT PARAMETERS:
;  none
; KEYWORD INPUT PARAMETERS:
;  none
; KEYWORD OUTPUT PARAMETERS:
;  none
; OUTPUTS:
;  R - rotation matrix for rotating an FGH vector to XYZ
;   FGH are defined as in Elliot et al. 1993. Astron. J. 106, 2544-2572
;     H is toward the occultation star
;     F is perpendicular to H and Z (Z x H)
;     G completes the right hand system
;
;    XYZ are defined in the usual manner
;     X = cos(ra_s) cos(dec_s)
;     Y = sin(ra_s) cos(dec_s)
;     Z =     sin(dec_s)
;
; COMMON BLOCKS:
;  None
; SIDE EFFECTS:
; RESTRICTIONS:
;  None
; PROCEDURE:
;
;  Since r is a rotation matrix, the inverse equals the transpose,
;  and we simply call oc_x2f_rotmat
;  
; USE:
;  The matrix is defined so that
;       xyz = R ## fgh     ; xyz, fgh column vectors
;  where xyz and fgh are column vectors (Array[1,3]) and ## is the
;  IDL operator for ordinary matrix multiplication (inner product).
;  It is usually more convenient to use fgh and xyz as row vectors
;  (Array[3]).  In this case we have
;       xyz = transpose(R) # fgh     ; xyz, fgh row vectors
;
; MODIFICATION HISTORY:
;  2005 Dec 29 Leslie A Young SwRI
;-

    rotmat = oc_x2f_rotmat(ra,dec)
    return, transpose(rotmat)

end