code: def write(self, outfile):
          
  
          hdu_pri = fits.PrimaryHDU()
  
          hdu_exp = self._create_exp_hdu(self.data)
          hdu_exp.name = 'EXPOSURE'
          hdu_exp_wt = self._create_exp_hdu(self._data_wt)
          hdu_exp_wt.name = 'WEIGHTED_EXPOSURE'
  
          cols = [Column(name='CTHETA_MIN', dtype='f4',
                         data=self.costh_edges[:-1][::-1]),
                  Column(name='CTHETA_MAX',  dtype='f4',
                         data=self.costh_edges[1:][::-1]), ]
          hdu_bnds = fits.table_to_hdu(Table(cols))
          hdu_bnds.name = 'CTHETABOUNDS'
  
          hdu_gti = fits.table_to_hdu(self._tab_gti)
          hdu_gti.name = 'GTI'
  
          hdus = [hdu_pri, hdu_exp, hdu_exp_wt,
                  hdu_bnds, hdu_gti]
  
          for hdu in hdus:
              hdu.header['TSTART'] = self.tstart
              hdu.header['TSTOP'] = self.tstop
  
          with fits.HDUList(hdus) as hdulist:
              hdulist.writeto(outfile, clobber=True)
docs: Write the livetime cube to a FITS file.