swcx uses the spectral fitting results from Xspec and model solar wind charge exchange (SWCX) detector maps (simply narrow band exposure maps created on a grid of energies) to create model SWCX contamination maps for a given observation. swcx includes the line-broadening effect of the response matrix (RMF).

Note that the SWCX lines are typically those found in the thermal spectra such as O VII and O VIII. Because of this, great care must be used in the determination of the SWCX contribution so that power isn't shifted to or from the cosmic plasma. This can best be accomplished where the object of interest does not fill the entire field of view or where there are multiple observations of the field. In the latter case the SWCX contribution can at least be reduced to the minimum level of contamination among the multiple observations by fitting their spectra simultaneously.


20ptThe current location should be the working directory.

20ptmos-spectra and mos_back and/or pn-spectra and pn_back must have been successfully run for the exposure to be used. The spectra produced by these tasks must be fit to determine the spectral parameters of the SWCX contamination. The spectrum should be modeled as a Gaussian of narrow or zero width (depending on whether the line is actually a complex of lines, e.g., O VII).

Calling Parameters:

20ptimagefile – Image created by mosback or pnback.

20ptspecfile – Spectrum created by mosback or pnback.

20ptswcxmapdet – Output SWCX map in detector coordinates.

20ptccds – These are flags to include or exclude individual CCDs for the MOS detectors (e.g., “T T T T T T T”), or to include or exclude the quadrants of the pn (e.g., “T T T T”).

20ptelow – The low energy limit for the energy band in eV (e.g., elow=400).

20ptehigh – The high energy limit for the energy band in eV (e.g., ehigh=1250).

20ptlines – list of SWCX lines to cast, for example $E\sim0.56$ keV for O VII, $E\sim0.65$ keV for O VIII, $E\sim0.81$ keV for O VIII, $E\sim0.91$ keV for Ne IX, and $E\sim1.34$ keV for Mg XI.

20ptgnorms – list of fitted Gaussian scale factors from Xspec in the same order as linelist.

20ptarffile – ARF for the exposure.

20ptrmffile – RMF for the exposure.


20ptprefix-swcximdet-elow-ehigh.fits – The model SWCX background image count image in detector coordinates.


20ptswcx imagefile=pn-fovimdet-300-1100.fits specfile=pn-fovt.pi ccds="T T T T" elow=300 ehigh=1100 rmffile=pn.rmf arffile=pn.arf lines="OVII OVIII" gnorms="1.69938e-7 1.75262e-8"