docs: def create_header_data(coord, radius=10., **kwargs):
      """ Make an empty sky region at location of skydir
      skydir : skymaps.SkyDir object
      size   : size of region (deg.)
      kwargs : arguments passed to create_header
      """
      header = create_header(coord, radius=radius, **kwargs)
      data = np.zeros( (header['NAXIS1'],header['NAXIS2']) )
      return header, data