XMM-Newton Data Center at MPE Creating RGS science files from incomplete ODF

This page will describe step-by-step what you have to do in order to create RGS science files from an incomplete RGS ODF. An incomplete ODF does contain the Auxiliary and the event files, but does not contain any housekeeping data. An incomplete ODf for the RGS would basically look like this:

1. Auxiliary files (one per spectrograph and exposure, e.g.

      0084_0099280101_R1S00100AUX.FIT    0084_0099280101_R2S00200AUX.FIT
      

2. Event files, one per CCD and exposure, e.g.

    
      0084_0099280101_R1S00101SPE.FIT    0084_0099280101_R2S00201SPE.FIT
      0084_0099280101_R1S00102SPE.FIT    0084_0099280101_R2S00202SPE.FIT
      0084_0099280101_R1S00103SPE.FIT    0084_0099280101_R2S00203SPE.FIT
      0084_0099280101_R1S00104SPE.FIT    0084_0099280101_R2S00204SPE.FIT
      0084_0099280101_R1S00105SPE.FIT    0084_0099280101_R2S00205SPE.FIT
      0084_0099280101_R1S00106SPE.FIT    0084_0099280101_R2S00206SPE.FIT
      0084_0099280101_R1S00107SPE.FIT    0084_0099280101_R2S00207SPE.FIT
      0084_0099280101_R1S00108SPE.FIT    0084_0099280101_R2S00208SPE.FIT
      0084_0099280101_R1S00109SPE.FIT    0084_0099280101_R2S00209SPE.FIT
      

3. Diagnostic files (if present, one per CCD): in our example, no diagnostic files are present for this observation.

In order to get RGS science data, please follow the following steps:

1. Transfer the ODf data to your disk.
   
   
2. Because our ODf is incomplete we have to create dummy housekeeping data by running the XMMSAS task odffix. Please follow the description given on the ODF fix page how to create a fixed ODF with dummy housekeeping files.
   
   
3. Follow the steps explained on the Get data page.
   
   
4. The processing of RGS science files form an incomplete ODF bases on the XMMSAS task rgsproc. This metatask works in four stages to precess events, source lists, exposure maps and creating spectra (source + background). The structure of the task rgsproc is explained on this GIF File (or can be seen on this Postscript File). This diagram also shows the four stages of the task rgsproc.
   
   As for complete data sets, run the XMMSAS task rgsproc.
   
   
5. This will create the following output files:
   
   
   1. Attitude history file ..._attitude.ds (one for the whole observation, e.g.:

            0084_0099280101_SCX00000_attitude.ds
            

   2. Event list file ..._events.ds, one per CCD and per exposure. In our example for RGS-1 and RGS-2:

            0084_0099280101_R1S00101_events.ds    0084_0099280101_R2S00201_events.ds
            0084_0099280101_R1S00102_events.ds    0084_0099280101_R2S00202_events.ds
            0084_0099280101_R1S00103_events.ds    0084_0099280101_R2S00203_events.ds
            0084_0099280101_R1S00104_events.ds    0084_0099280101_R2S00204_events.ds
            0084_0099280101_R1S00105_events.ds    0084_0099280101_R2S00205_events.ds
            0084_0099280101_R1S00106_events.ds    0084_0099280101_R2S00206_events.ds
            0084_0099280101_R1S00107_events.ds    0084_0099280101_R2S00207_events.ds
            0084_0099280101_R1S00108_events.ds    0084_0099280101_R2S00208_events.ds
            0084_0099280101_R1S00109_events.ds    0084_0099280101_R2S00209_events.ds
            

   3. Merged event list file ..._merged.ds, one per RGS per exposure, e.g.:

            0084_0099280101_R1S00100_merged.ds    0084_0099280101_R2S00200_merged.ds
            

   4. Filtered merged event list file ..._filtered.ds, one per RGS per exposure. These files are created by the XMMSAS task evselect in the third stage of rgsproc. In our example, the filtered event list files are:

          0084_0099280101_R1S00100_filtered.ds    0084_0099280101_R2S00200_filtered.ds
          

   5. Source list of targets and associated extraction regions ..._sources.ds, one per RGS and exposure, e.g.:

          0084_0099280101_R1S00100_sources.ds    0084_0099280101_R2S00200_sources.ds
          

   6. exposure maps ...expmap.ds, one per RGS per exposure, e.g.:

          0084_0099280101_R1S00100_expmap.ds    0084_0099280101_R2S00200_expmap.ds
          

   7. Background spectrum for primary source ..._bkg....ds, with one file per per RGS source per exposure per order, e.g.:
      
      First order:

          0084_0099280101_R1S00100_bkg1o1.pha    0084_0099280101_R2S00200_bkg1o1.pha
          

      Second order:

          0084_0099280101_R1S00100_bkg1o2.pha    0084_0099280101_R2S00200_bkg1o2.pha
          

   8. Background subtracted source spectrum ..._net....ds, one per RGS per source per order per exposure, e.g.:
      
      First order:

         0084_0099280101_R1S00100_net1o1.pha    0084_0099280101_R2S00200_net1o1.pha
         

      Second order:

         0084_0099280101_R1S00100_net1o2.pha    0084_0099280101_R2S00200_net1o2.pha
         

6. In order to examine your results, the first step is to use the XMMSAS evselect to create a spatial-dispersion image and an energy-dispersion image (also called banana plot for obvious reason).:
   
   The spatial dispersion image is created by the aspect corrected dispersion angle BETA_CORR and the cross-dispersion angle XDSP_CORR:

   evselect table=0084_0099280101_R1S00100_filtered.ds withimageset=true \
            xcolumn=BETA_CORR ycolumn=XDSP_CORR imageset=image_r1.fits
       

   The banana plot energy-dispersion image is created by using the aspect corrected dispersion angle BETA_CORR and the PI energy channel:

   evselect table=0084_0099280101_R1S00100_filtered.ds withimageset=true \
            xcolumn=BETA_CORR ycolumn=PI imageset=image_r1_banana.fits
       

   The two images look like this (displayed with DS9):
   
   

   RGS spatial image plot

   RGS banana image plot

   
   
   
7. To display a spatial-dispersion plot and an energy-dispersion plot together with overlays that display the regions where the photons for the spectra were extracted the XMMSAS task rgsimplot is used:

    
      rgsimplot device=/CPS srclistset=0084_0099280101_R1S00100_sources.ds \
                endispset=image_r1_banana.fits spatialset=image_r1.fits \
   	     plotfile=R1_plot.ps
      

   In this way the output device is set to a postscript file (/CPS) with the name R1_plot.ps . The default output devise in a PGPLOT Xwindow /XW on the screen.
   
   
8. There is one problem with incomplete ODFs: The coordinates you give in the XMMSAS task odffix do not include any corrections for boresight between the different istruments onboard XMM. Therefore the spatial region for selecting your source photons will be wrong. In the display created by rgsimplot it will look like in the example given below:
   
   

   Display created by rgsimplot with wrong coordinates

   
   
   The selection region in the spatial plane is not where the source is. In order to correct this, create an image from the EPIC data (MOS or PN), as explained on the Simple image page. Then measure the coordinates in the image by using your favourit imagedisplay, e.g. DS9. You will see that this coordinate is slighly different to the source position you have given in odffix. Now, follow the steps as explained on the RGS advanced tasks page starting with rgssources. If you now run rgsimplot again with the new source, the plot will look like this:
   
   

   Display created by rgsimplot with the right coordinates

   
   
   
9. To display the spectra (...pha files) you can use the XMMSAS task dsplot:

      dsplot table=0084_0099280101_R1S00100_net1o1.pha withx=true withy=true \
             x=CHANNEL y=RATE
      

   The raw spectra in first and second order look like this:
   
   

   RGS first order spectrum

   RGS second order spectrum

© X-Ray Group at MPE (group)
last update:2008-01-14, editor of this page:Frank Haberl, Dirk Grupe