n 
               opened for writing. 
 
   body        is the NAIF ID for the body whose states are 
               to be recorded in an SPK file. 
 
   center      is the NAIF ID for the center of motion associated 
               with BODY. 
 
   frame       is the reference frame that states are referenced to, 
               for example &quot;J2000&quot;. 
 
   first       are the bounds on the ephemeris times, expressed as 
   last        seconds past J2000, for which the states can be used 
         