compute the background lightcurve of the problem event file applying the following selection expression CCDNR==9 AND (XDSP_CORR < -3.E-4 OR XDSP_CORR > 3.E-4) From the lightcurve, calculate the fraction of the total time for each of the pre-defined levels of background. Compute the background template spectra by weighting each of the template spectra by the corresponding factor calculated from the ligthcurve.