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

Developped for XMMSAS version 5.3.3

This page will describe what you have to do in order to create RGS science files from an RGS ODF. It focus on the most simplest usage of the RGS data reduction task. If you want/need to perform a more advanced processing, please have a look at the RGS Advanced tasks page.. Please make sure that you have a complete ODF in case you are using data from observations with revolution numbers less than 102. If you are not sure, please check the odffix page how to see if the observation was complete or not and how to fix an incomplete ODF.

Before you start to create RGS science files from the ODF, please make sure that the ODF directory is set and that you have created a summary file ...SUM.SAS by the XMMSAS task odfingest and a Current Calibration Index File (CIF). Please check the System Setup page for descriptions.

A description of an RGS ODF can be found on RGS ODF description page. The processing of RGS science files bases on the XMMSAS task rgsproc. This metatask works in five stages to precess events, source lists, exposure maps, creating spectra (source + background), and flux calibrated spectra (including response files). The structure of the task rgsproc is explained on this GIF File (or can be seen on this Postscript File). This diagram shows the five stages of the task rgsproc.

To work with RGS data perform the follwoing steps:

1. The most easiest way is to simply run the task rgsproc with the default parameter settings:

         rgsproc
   

   This will create the following output files:
   
   
   1. Attitude information file ...ATTTSR....FIT (one for the whole observation), e.g.:

            P0103660201OBX000ATTTSR0000.FIT
            

   2. Good Time Intervals from attitude history file ...attgti....FIT (one for the whole observation), e.g.:

            P0103660201OBX000attgti0000.FIT
            

   3. Good Time Intervals from housekeeping file ...hkgti_....FIT (one per RGS1 and 2), e.g.:

            P0103660201R1X000hkgti_0000.FIT
            

   4. Merged event list from all CCDs ..._merged....FIT, one per RGS per exposure, e.g.:

            P0103660201R1S004merged0000.FIT
            

   5. Filtered merged event list file ...EVENLI....FIT, 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 file of RGS1 is:

            P0103660201R1S004EVENLI0000.FIT
          

   6. Source list of targets and associated extraction regions ...SRCLI_....FIT, one per RGS and exposure, e.g.:

            P0103660201R1S004SRCLI_0000.FIT
          

   7. Exposure maps ...EXPMAP....FIT, one per RGS per exposure, e.g.:

            P0103660201R1S004EXPMAP0000.FIT
          

   8. Background spectrum for primary source ...BGSPEC....FIT, with one file per per RGS source per exposure per order, e.g.:
      
      First order:

            P0103660201R1S004BGSPEC1001.FIT
          

      Second order:

            P0103660201R1S004BGSPEC2001.FIT
          

   9. Background subtracted source spectrum ...SRSPEC....FIT one per RGS per source per order per exposure, e.g.:
      
      First order:

            P0103660201R1S004SRSPEC1001.FIT
         

      Second order:

            P0103660201R1S004SRSPEC2001.FIT
         

   10. Response matrix ...matrix....FIT one per RGS per source per order per exposure, e.g.:
       
       First order:

             P0103660201R1S004matrix1001.FIT
          

       Second order:

             P0103660201R1S004matrix2001.FIT
          

   11. Fluxed spectrum...fluxed....FIT one per RGS per source per order per exposure, e.g.:
       
       First order:

             P0103660201R1S004fluxed1000.FIT
          

2. The example given above creates the source spectra for RGS1 and 2 in first and second order. However, there may be cases in which you would like to process only the spectrum of a source from one RGS in one order. Here is an example tp create a spectrum in first order of RGS 1 only:

          rgsproc withinstexpids=true instexpids=R1S004 orders=1
      

3. 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 nothing else as a 2-dimensional spectrum (e.g. in optical CCD spectroscopy), where in our case the y-axis is the spatial axis and the x-axis is the dispersion in energy/wavelength-axis. On this image you can identify if more than one sources have been seen in the RGS. The energy-dispersion image displays the spectral resolution of the CCD detector (like the EPIC CCDs) vs. the dispersion of the spectrograph.
   
   The spatial dispersion image is created by the aspect corrected dispersion angle BETA_CORR and the cross-dispersion angle XDSP_CORR:

    evselect table=P0103660201R1S004EVENLI0000.FIT \
             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=P0103660201R1S004EVENLI0000.FIT \
             withimageset=true xcolumn=BETA_CORR ycolumn=PI \
   	  imageset=image_r1_banana.fits
       

   The example shown below is from an observation of the eclipsing spectroscopic binary star YY Gem (see e.g. Stelzer et al. 2002) from orbit 0069 during the Cal PV phase of XMM. Please note that in later observations due to electronic problems in RGS1 CCD 7 and in RGS 2 CCD 4 do not work anymore. The two images look like this (displayed with DS9):
   
   

   RGS spatial image plot

   RGS banana image plot

   
   
   
4. 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=P0103660201R1S004SRCLI_0000.FIT \
    	   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:
   
   

   RGS rgsimplot result

   
   
   The Source file P0103660201R1S004SRCLI_0000.FIT is used to display the regions where the source photons were selected. The plot also displays where the photons of the calibration source were extracted.
   
   
5. To display the spectra (...pha files) you can use the XMMSAS task dsplot:

      dsplot table=P0123710101R1S004SRSPEC1001.FIT withx=true withy=true 
             x=CHANNEL y=COUNTS
      

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

   RGS first order spectrum

   RGS second order spectrum

© Roentgengruppe des MPE (group)
letzte Änderung:2008-01-14, Editor dieser Seite:Frank Haberl, Dirk Grupe