Here we present two examples of the use of SciSim in the preparation of an XMM observing proposal, one each for EPIC and RGS. Note that the SciSim online help also contains two tutorials for source simulations.
CAVEAT 1: When importing model spectra created in xspec into SciSim, these spectra must be created with an energy grid that is dense enough so as to be smaller than the energy resolution of the instruments (in particular RGS)! Otherwise, the input spectrum will already determine the ``resolution'' of the output ``model''. A 0.1 eV energy grid is sufficient to sample RGS spectra adequately. For EPIC simulations a spectral bin width of 10 eV should suffice. The energy grid should best be defined using the available response matrices. Alternatively, the grid can be defined in the xspec task dummyrsp as the increment parameter.
Until the XMM Data Archive will be populated with CCFs, preliminary response matrices can be retrieved from the XMM calibration area on the SOC web server.