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XMM-Newton Science Analysis System


esensitivity (esensitivity-1.5) [xmmsas_20050815_1803-6.5.0]

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Caveats

There are many ways in which sources might be detected and selected; however esensitivity is designed to cope with only a single method, namely the sliding-box detection on parallel images as performed by eboxdetect. The task cannot determine the details of the detection method for itself, thus it is up to the user to ensure that the parameters used to invoke esensitivity match those of the corresponding call to eboxdetect. Ideally eboxdetect should be called using the following parameter settings:

• -bkgimagesets=list of $N$ background maps $\beta_i$

• -usemap=yes

• -detmasksets=list of $N$ detector masks (made from exposure maps by emask

• -expimagesets=list of $N$ exposure maps $\epsilon_i$

• -nruns=1. NOTE that this is neither the default value nor that used in the XMM pipeline.

• -likemin= $L_{\rm {cutoff}}$

• -boxsize=$b$

• -imagesets=list of $N$ images $I_i$

• -boxlistset=output file name

• -pimin=list of $N$ lower bounds $E_{i,\rm {lo}}$ of the input images etc

• -pimax=list of $N$ upper bounds $E_{i,\rm {hi}}$ of the input images etc

The correct matching call of esensitivity uses the corresponding values of the appropriate parameters, viz:

• -bkgmapsets=list of $N$ background maps $\beta_i$

• -expmapsets=list of $N$ exposure maps $\epsilon_i$

• -likemin= $L_{\rm {cutoff}}$

• -boxhalfsize=$(b-1)/2$. Note that $b$ as presently defined in eboxdetect is always odd.

Note that esensitivity also needs to know the mean energies $E_{i,\rm {mean}}=(E_{i,\rm {hi}} + E_{i,\rm {lo}})/2$. If the energy bands are stored in the data subspaces (DSSs) of the images, then the user should set psfestyle=`dss' and supply the list of images $I_i$ to dssimagesets; if not, the parameter psfestyle will need to be set to `user' (currently the default value) and a list of the mean values explicitly supplied via the parameter psfenergies.

It should be emphasised that esensitivity cannot yet be made to match the complicated source detection and selection procedure which is currently used to make XMM-product source lists. Application of esensitivity to such lists will probably produce results which are apprximately correct but the degree of approximation is not known and for this reason I don't recommend the procedure. In future I hope we will make changes to the way these product source lists are made which will allow matching sensitivity maps to be made.