As mentioned above, it is recommended to use the default RGS configuration in SciSim, which is FM2, until geometrical configuration files for other combinations have been added to SciSim.
To produce the RGS spectrum shown in Fig. 47 in
§ 3.4.2, a two-component Raymond-Smith thermal plasma
model spectrum was created with xspec and imported into SciSim.
The model consists of a 0.35 keV and a 2.0 keV component of equal flux.
The adopted source intensity is
photons s-1
cm-2 in the RGS band (0.35-2.5 keV). The resolution of the
xspec-created input model was chosen to be 0.1 eV, i.e., higher
than the RGS's energy resolution. Importing the spectrum from the
SciSim GUI works as described above in the example for an EPIC
simulation.
Under the top-level GUI option ``Configure'', which spawns the configuration GUI, the ``RayGen'', ``Mirror'', ``RGA'' and ``RFC'' modules were switched on by clicking on the icons with the left mouse button. Clicking on the RayGen icon with the right mouse button, the integration time was set to 40000 [s]. Clicking on the mirror module icon (with the right mouse button), one can choose between different mirror modules. The same procedure can be followed to choose a particular RGA and RFC by clicking on the respective icon. Again, as for EPIC simulations, for a ``standard'' model simulation neither any spacecraft effects nor other options regarding the mirrors and instruments need to be specified. Most of the options offered there are included for instrument calibration purposes. Spacecraft effects are included based on the current best guess of the expected pointing performance.
Once all inputs are specified, the simulation is started by clicking on the ``start'' button at the bottom of the GUI (or ``Simulate'' ``Start'' in the top menu). While the simulation is running, a performance bar will inform the user of its progress.
Upon successful completion the results of the model run are contained in a file named ``tempf'', which is created on the current directory (i.e., the one from which SciSim has been started). To convert the data into a form readable by existing software, tools are provided (reporter2pha and reporter2fits) to produce a PHA format output spectrum. This spectrum can then be transfered into xspec for analysis or for display.
CAVEAT: When modeling RGS observations with SciSim, the default instrument configuration should be used, which is ``FM2''. FM2 (Flight Model 2) represents RGA-2, which is part of RGS-1. For this configuration the geometrical configuration is implemented correctly in SciSim. Using FM1 instead, users would need to obtain and manually insert the geometrical configuration, because the geometrical alignment of both RGA-1 with respect to its mirror module and RFC-1 with respect to RGA-1 differs from those of FM2.