I am unable to analyze RGS products, created with SAS v5.0, using later versions of SAS. Is there a workaround?

Due to a change of the structure of the RGS event lists and RGS source list files since SAS 5.1, it is necessary to convert products that where generated with SAS 5.0 to the format required by SAS 5.1 tasks, mainly rgsrmfgen. You can find out, if your event lists need to be updated by inquiring the spectrum product with the following command:

playback withscriptfile=n sets=PppppppppppRiSeeeSRSPEC1003.FIT \
|& grep rgsspectrum

The output contains a string like [xmmsas_yyyymmdd_tttt], which is an encoding of the date of the SAS. If that date is before 20010411, then updating of the data files is needed.

The recipe below lists the steps to be taken for one exposure of one instrument. It needs to be repeated per instrument. Note that in the following:

• pppppppppp is the proposal number
• i is the instrument number (1 or 2)
• eee is the exposure number

The following steps need to be taken:

1. set the environment variables SAS_ODF and SAS_CCF
2. convert all the event lists
   rgsevconvert set=PppppppppppRiSeeeEVENLI0000.FIT
3. convert all the source lists
   rgssources rgsset=PppppppppppRiSeeeSRCLI_0000.FIT
4. delete the background region extension
   dsrm objects=PppppppppppRiSeeeSRCLI_0000.FIT:RGSi_BACKGROUND
5. re-generate background selection region for proper background spectrum
   rgsregions eventset=PppppppppppRiSeeeEVENLI0000.FIT \
   set=PppppppppppRiSeeeSRCLI_0000.FIT
6. extract spectra per order and per source (here only for one order/source)
   rgsspectrum file=PppppppppppRiSeeeSPEC1003.FIT order=1 source=3 \
   set=PppppppppppRiSeeeEVENLI0000.FIT \
   sourceset=PppppppppppRiSeeeSRCLI_0000.FIT

Step 4. in the above recipe is due to the fact that rgsregion cannot overwrite extensions of a source list file.

After this rgsrmfgen can be started in the usual way, e.g. by:

rgsrmfgen ebins=13000 emax=2.3 emin=0.3 file=r1o1.rmf order=1 \
set=PppppppppppRiSeeeEVENLI0000.FIT \
source=3 sourceset=PppppppppppRiSeeeSRCLI_0000.FIT \
spectrumset=PppppppppppRiSeeeSPEC1003.FIT withspectrum=yes

The value of the parameter ebins in rgsrmfgen has a significant impact on the computation time. Although the default specified above is the optimal choice, smaller values (>~ 3000) may be accurate enough for most scientific purposes or testing.