factor_rsp Synopsis: factor the extraction region effiency term from a grating response matrix and includes it in the corresponding grating effective area file. Requirements: factor_rsp will run from any shell which has isis-script in your path, such as a shell configured for CIAO 3.2. USAGE: > factor_rsp grmf_in garf_in garf_out [ eefrac_out ] Inputs: grmf_in: Input grating response matrix file (RMF) garf_in: Input grating auxiliary response file (ARF) Outputs: garf_out: Output grating ARF, which is the input ARF multipled by the EEFRAC factored from the grating RMF. eefrac_out: If this argument is given, the EEFRAC is written to a file in ARF format. For Chandra diffraction grating data analysis, we recommend use of both the grating effective area file (ARF) and the grating response matrix file (RMF). The ARF contains the effective area (integrated over dither, including detector non-uniformities for a specific source position) for a two-pi radian region in the cross-dispersion direction. The RMF contains an extraction region efficiency term, the enclosed energy fraction (EEFRAC), since this is tightly coupled to the line spread function (LSF); the EEFRAC and LSF are determined by the choice of cross-dispersion region from which the spectrum has been binned, and are tabulated in the calibration database "lsfparm" files. For further details on the grating ARF and RMF computation, see the CIAO help files for mkgarf and mkgrmf. Some analysts may prefer to use only the ARF, for instance, during proposal planning when only net counts are of interest, not the LSF, or in doing parametric fitting of the instrumental profile. For such analysis to be more accurate, the ARF needs to include the EEFRAC. A script, factor_rsp, has been provided to support such analysis. The script will factor EEFRAC from an RMF and multiply it into an ARF, and write the resulting ARF to disk. Note: there is no provision to write the factored RMF. While RMF-less analysis is sometimes appropriate, if one needs and RMF, you also need the ARF. There is no equivalnt RMF-only analysis, unless the RMF includes the full effective area. CIAO does not provide for computation the the "FULL" RMF.