XMM-Newton Further EPIC Background Scripts

This page contains the following scripts:

• Estimation of the residual Soft Proton flare contamination
• Background correction for faint extended EPIC PN emission

Estimation of the residual Soft Proton flare contamination

A shell script to perform the Fin/Fout ratio calculation developed by Silvano Molendi, Andrea De Luca & Alberto Leccardi (2004, A&A 419, 837) on EPIC event files (MOS1, MOS2 and/or pn), to estimate the amount of residual Soft Proton flare contamination is available.

The script can be run on any EPIC event files (MOS1, MOS2 and/or pn), to estimate the amount of *residual* Soft Proton (SP) flare contamination, i.e. it should only be used *after* attempts have been made to clean the event files for SPs using GTI filtering.

The script compares area-corrected count rates in the in-FOV (beyond 10 arcminutes) and out-of-FOV regions of the detector. The higher the in-FOV to out-of-FOV ratio, the more the file is contaminated by SPs:

Ratio < 1.15	: File is not contaminated by SPs.
Ratio 1.15-1.3	: File is slightly contaminated by SPs.
Ratio 1.3-1.5	: File is very contaminated by SPs.
Ratio > 1.5	: File is extremely contaminated by SPs.

For point source analysis, and especially for bright point sources, a rigorously correct treatment of the background is not critical, and even extremely SP contaminated files may be analysed safely in the usual manner.

For extended source analysis however, even a moderate amount of residual SP contamination may lead to corrupted science results, especially e.g. in the estimated temperature. Here the user may wish to, depending on what they are trying to do, use another (cleaner) observation (of the same or a different target). Or they may attempt to remove the residual SPs using more complex data screening (some descriptions of various techniques are given in the Other Useful Information section of the main ESAC-XMM Background Analysis page). If the data allow, the user could also attempt to include the SP contamination as an extra model component, when modelling the data (e.g. in spectral fitting).

Note finally that for observations where an extended source fills the entire field of view (FOV), e.g. the Coma cluster, then the Fin_over_Fout script does not yield a reliable measurement of the SP contamination. Care should be taken in such situations.

The script may be downloaded here.

After downloading the file, the script will need to be made executable:

    chmod 755 Fin_over_Fout

For details on how the script works, type:

    ./Fin_over_Fout

Script use:

    ./Fin_over_Fout m1ev m2ev pnev elo ehi keepfiles outfile

Where;

  m1ev      - MOS1 event file (N = ignore)
  m2ev      - MOS2 event file (N = ignore)
  pnev      - pn event file   (N = ignore)
  elo       - low-energy threshold  [eV] (N = use recommended default values)
  ehi       - high-energy threshold [eV] (N = use recommended default values)
  keepfiles - keep intermediate files (Y/N)
  outfile   - ouput file name (N = just output to screen)

Example call:

    ./Fin_over_Fout myM1ev.fits myM2ev.fits N 7000 12000 Y MyFinFout.dat

Background correction for faint extended EPIC PN emission

A script together with information regarding Bauer et al's (2007) method to use a local estimate of the sky background to correct for faint extended emission in EPIC-PN data is available here. Support is however no longer provided.