XMM-Newton Science Analysis System: User Guide


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Next: 6.6.2 Example of fast mode data processing Up: 6.6 Running the OM data processing Previous: 6.6 Running the OM data processing


6.6.1 Example of image data processing

Due to the number of input parameters, lengthy file names, etc, it is not recommended to run any OM chain step by step. Only in special cases, some tasks, as omdetect, ommag, omatt, omsrclistcomb, lcplot, may have to be run so as to fine tune some parameters. In some cases it might be more advantageous to use the interactive omsource or omgsource.

To process task by task a single exposure in image mode, in addition to the house-keeping files listed in Table 10, the following files are needed:

0472_0125910501_SCX00000SUM.SAS  - ASCII observation summary file 
0472_0125910501_SCX00000TCS.FIT  - Spacecraft Time correlation file
0472_0125910501_SCX00000RAS.ASC  - Spacecraft Raw Attitude file
0472_0125910501_OMS00400WDX.FIT  - Exposure priority window file
0472_0125910501_OMS00400THX.FIT  - Exposure tracking history file
0472_0125910501_OMS00400IMI.FIT  - Exposure image file to process

These files can be located in the working directory, or in any other one, providing that the environment variable SAS_ODF has been set accordingly. In our examples it is assumed that all necessary files are in the working directory.

The process will be run in the following way.

Although, as said before, no real flat field correction exists for OM, nor it is necessary, the processing requires such a file which can be generated using the task omflatgen as follows.

step0> omflatgen outset=P0125910501OMX000FLAFLD0000.FIT

The output flatfield (primary extension) will be set to unity.

step1> omprep set=0472_0125910501_OMS00400THX.FIT \
              nphset=0472_0125910501_OMX00000NPH.FIT \ 
              pehset=0472_0125910501_OMX00000PEH.FIT \ 
              wdxset=0472_0125910501_OMS00400WDX.FIT \ 
              outset=tmp_tracking modeset=3

In case there is no THX file, then set=DUMMYTHX.FIT. omprep will generate a dummy file needed for the rest of the chain, with zero drift in it.

step2> omdrifthist set=tmp_tracking plotfile=P0125910501OMS004TSHPLT0000.ps

step3> omthconv thxset=tmp_tracking nphset=0472_0125910501_OMX00000NPH.FIT \ 
                outset=P0125910501OMS004TSTRTS0000.FIT  modeset=0

step4> omprep set=0472_0125910501_OMS00400IMI.FIT \
              nphset=0472_0125910501_OMX00000NPH.FIT \
              pehset=0472_0125910501_OMX00000PEH.FIT \ 
              wdxset=0472_0125910501_OMS00400WDX.FIT \ 
              outset=tmp_image_1 modeset=0

step5> omcosflag set=tmp_image_1 thxset=tmp_tracking \
                 samplefactor=1 timefactor=1

step6> omflatfield set=tmp_image_1 thxset=tmp_tracking \ 
                   inorbitflatset=P0125910501OMX000FLAFLD0000.FIT \
                   tsflatset=tmp_flat_field outset=tmp_image_2 \
                   samplefactor=1

step7> ommodmap set=tmp_image_2 mod8product=yes mod8set=tmp_mod8 \ 
                outset=P0125910501OMS004IMAGE_0000.FIT \
                nsig=3 nbox=16 mod8correction=1

step8> omqualitymap srclistset=' ' \
                    set=P0125910501OMS004IMAGE_0000.FIT \
                    outset=I0125910501OMS004QIMAG_0000.FIT \
                    mode=setqualityimage

step9> omdetect set=I0125910501OMS004QIMAG_0000.FIT \
                outset=P0125910501_OMS004SWSRLI0000.FIT \
                levelimage=level_image regionfile=region_file \
                nsigma=2 minsignificance=1 detectextended=yes

step10> omqualitymap srclistset=/P0125910501_OMS004SWSRLI0000.FIT \
                    set=I0125910501OMS004QIMAG_0000.FIT \
                    outset=P0125910501OMS004QIMA2_0000.FIT \
                    mode=setqualityimage


step11> ommag set=P0125910501_OMS004SWSRLI0000.FIT \

step12> omatt set=P0125910501OMS004QIMA2_0000.FIT \ 
              sourcelistset=P0125910501_OMS004SWSRLI0000.FIT \ 
              ppsoswset=P0125910501OMS004SIMAGE0000.FIT

The detected sources can be overlaid on the OSW by using implot, or ds9.

In the standard automatic SOC pipeline processing, the tmp_image files are re$-$used and thus overwritten. In the task by task processing, they are distinguished so that intermediate stage output can be inspected if desired. In the above example, product names are used where they are similarly used in the SOC pipeline.

The sky images of the multiple exposures corresponding to the default image configuration, as well as images in user defined mode with the same filter, can be combined in a single sky image of the field of view.

Starting with SAS 9, an additional detection can be done on mosaiced images. This will allow us to find fainter sources. The optional parameter processmosaicedimages=yes in omichain has to be used. Please refer to the on-line documentation for more details.

step13> ommosaic imagesets="list of sky images" \ 
                 mosaicedset=myfield_in_myfilter.fit

Finally, if multiple images with different filters are processed, the source lists can be combined as follows.

step14> omsrclistcomb sourcelistsets=P0125910501OMS004SWSRLI0000.FIT,..... \
                         nsigma=3 outset=P0125910501OMS000OBSMLI0000.FIT

where .......... is a continuing list of SWSRLI files.

In case we have multiple exposures with the same filter(s) we can now run (since SAS 10) omvariability

step15> omvariability directorylist='' \ 
                      srclistsets='sourcelist1 sourcelist2 ...' \
                      obsset=P0125910501OMS000OBSMLI0000.FIT  \
                      plotfile=sasdev3/P0125910501OMLIGHTCURVE0000.ps  \
                      minstd=2 minnumcounterparts=2 nxsub=1 nysub=3   \
                      eflag=-1 cflag=-1 qflag=-1

If we want to search for fainter sources using mosaic or stacked images, after processing all of them and using these new images we continue as follows

step16> omdetect set=myfield_in_myfilter.FIT   \
                 outset=myfield_in_myfilter_sourcelist.FIT   \
                 regionfile=mosaic_stacked_image.reg

step17> ommag set=mosaic_sourcelist.FIT

step18> omqualitymap srclistset=filter_mosaic_sourcelist.FIT  \
                     set=myfield_in_myfilter.FIT    \
                     outset=filter_mosaic_sourcelist.FIT   \
                     mode=usequalityimage

step19> omsrclistcomb sourcelistsets='list of filter_mosaic_source_lists'  \
                      outset='combined_source_list_all_mosaic_images.FIT' 

step20> ommergelists srclist1=P0125910501OMS000OBSMLI0000.FIT  \
                     srclist2=combined_source_list_all_mosaic_images.FIT   \
                     outset=myfield_inallfilters_merged_source_list.FIT


next up previous contents
Next: 6.6.2 Example of fast mode data processing Up: 6.6 Running the OM data processing Previous: 6.6 Running the OM data processing
European Space Agency - XMM-Newton Science Operations Centre