docs: def _fit_radec(self):
          """
          call fit_radec of BK passing in the observations.
  
          """
  
          # call fitradec with mpcfile, abgfile, resfile
          self.orbfit.fitradec.restype = ctypes.c_int
          self.orbfit.fitradec.argtypes = [ ctypes.c_char_p, ctypes.c_char_p, ctypes.c_char_p ]
  
          mpc_file = tempfile.NamedTemporaryFile(suffix='.mpc')
          for observation in self.observations:
              mpc_file.write("{}\n".format(str(observation)))
          mpc_file.seek(0)
  
          abg_file = tempfile.NamedTemporaryFile()
          res_file = tempfile.NamedTemporaryFile()
  
          self.orbfit.fitradec(ctypes.c_char_p(mpc_file.name),
                               ctypes.c_char_p(abg_file.name),
                               ctypes.c_char_p(res_file.name))
  
          self.abg = abg_file
          self.abg.seek(0)
          self.residuals = res_file
          self.residuals.seek(0)