         between them. The aberration angle phi is given by 
 
            sin(phi) = v sin(w) / c 
 
         Let h be the vector given by the cross product 
 
            h = r X v 
 
         Rotate r by phi radians about h to obtain the apparent 
         position of the object. 
 
 
      Transmission case 
      ================== 
 
      When any of the options &quot;XLT&quot;, &quot;XCN&quot;, &quot;XLT+S&quot;, &quot;XCN+S&quot; is 
      selected, <b>spkpos_c</b> computes the position of the targ