code: def _load_data(self, band):
          
          # `band` should be 'Lp'.
          df = bandpass_data_frame('filter_mko_' + band + '.dat', 'wlen resp')
          # Put in increasing wavelength order:
          df = df[::-1]
          df.index = np.arange(df.shape[0])
          df.wlen *= 1e4 # micron to Angstrom
          df.resp *= df.wlen # QE to equal-energy response.
          return df
docs: Filter responses for MKO NIR filters as specified in Tokunaga+ 2002 (see
          also Tokunaga+ 2005). I downloaded the L' profile from
          http://irtfweb.ifa.hawaii.edu/~nsfcam/hist/filters.2006.html.
  
          Pivot wavelengths from Tokunaga+ 2005 (Table 2) confirm that the
          profile is in QE convention, although my calculation of the pivot
          wavelength for L' is actually closer if I assume otherwise. M' and K_s
          are substantially better in QE convention, though, and based on the
          paper and nomenclature it seems more appropriate.