The task writes the names of the created files into the source spectrum header keywords, BACKFILE, RESPFILE, ANCRFILE. These may be automatically read by spectral fitting programs to link the files and perform area weighted background subtraction, e.g. for xspec.
XSPEC>data myagn_src.ds Net count rate (cts/s) for file 1 5.049 +/- 2.6091E-02( 98.5% total) using response (RMF) file... myagn_src.rmf using auxiliary (ARF) file... myagn_src.arf using background file... myagn_bgd.ds 1 data set is in use XSPEC>
