With the help of the IBIS_SI_inEnergyValues parameter, or of the other sets of parameters, you can specify the desired energy bins, as detailed in Sect. . Since OSA11, the response matrix (RMF) of ISGRI is computed for sets of contiguous revolutions. You do not need to provide a RMF rebinned accordingly to the energy bins you specified for the spectral analysis. This step is now automatised by the analysis script. At the end of the analysis run, you will find, together with the spectral results, also the rebinned RMF that correspond to your data.
After terminating the analysis, the spectral results for a given source can be combined via the spe_pick command. In this case the command will also provide an averaged RMF for the time covered by your data, rebinned accordingly to the spectral bins used for the analysis.