code: def spkgps(targ, et, ref, obs):
      
      targ = ctypes.c_int(targ)
      et = ctypes.c_double(et)
      ref = stypes.stringToCharP(ref)
      obs = ctypes.c_int(obs)
      position = stypes.emptyDoubleVector(3)
      lt = ctypes.c_double()
      libspice.spkgps_c(targ, et, ref, obs, position, ctypes.byref(lt))
      return stypes.cVectorToPython(position), lt.value
docs: Compute the geometric position of a target body relative to an
      observing body.
  
      http://naif.jpl.nasa.gov/pub/naif/toolkit_docs/C/cspice/spkgps_c.html
  
      :param targ: Target body.
      :type targ: int
      :param et: Target epoch.
      :type et: float
      :param ref: Target reference frame.
      :type ref: str
      :param obs: Observing body.
      :type obs: int
      :return: Position of target, Light time.
      :rtype: tuple