code: def _load_aux_image(self, image, auxfile):
          
          auximg = FitsImage(auxfile, beam=self.global_data.beam).get_pixels()
          if auximg.shape != image.get_pixels().shape:
              self.log.error("file {0} is not the same size as the image map".format(auxfile))
              self.log.error("{0}= {1}, image = {2}".format(auxfile, auximg.shape, image.get_pixels().shape))
              sys.exit(1)
          return auximg
docs: Load a fits file (bkg/rms/curve) and make sure that
          it is the same shape as the main image.
  
          Parameters
          ----------
          image : :class:`AegeanTools.fits_image.FitsImage`
              The main image that has already been loaded.
  
          auxfile : str or HDUList
              The auxiliary file to be loaded.
  
          Returns
          -------
          aux : :class:`AegeanTools.fits_image.FitsImage`
              The loaded image.