Create a ``dummy'' response, covering a given energy range.
XSPEC> dummyrsp [<Low Energy> [<High Energy> [<# of ranges> [<log or linear> [<channel offset> [<channel width>]]]]]]
This command creates a dummy response matrix based on the given command line arguments, which will either temporarily supersede the current response matrix, or create a response matrix if one is not currently present. There are two main uses for this command: to do a ``quick and dirty'' analysis of uncalibrated data, and to examine the behaviour of the current model outside the range of the data's energy response.
In the first instance, one has a data set for which no response matrix is currently available. This command will create a diagonal response matrix with perfect efficiency. The response matrix will range in energy from <Low Energy> to <High Energy>, using <# of ranges> as the number of steps into which the range is logarithmicly or linearly divided. The detector channels are assigned to have widths of energy <channel width> (specified in keV), the lower bound of the first channel starting at an energy of <channel offset>. The response matrix is then set so that the channel values are mapped directly into the corresponding energy ranges. Then the data can be fit to models, etc., under conditions that assume a perfect detector response.
In the second instance, one can use this command to examine the current model outside the range of the energy response of the detector. When examining several aspects of the current model, such as plotting it or determining flux, XSPEC uses the current evaluation array. This, in turn, is defined by the current response files being used, which depend on the various detectors. For example, low energy datasets (such as those from the EXOSAT LEs) may have responses covering 0.05 to 2 keV, while non-imaging proportional counters can span the range from 1 to 30 keV. If the user wishes to examine the behavior of the model outside of the current range, then he or she temporarily must create a dummy response file that will cause the model to be evaluated from <Low Energy> to <High Energy>, using <# of ranges> as the number of steps into which the range is logarithmicly or linearly divided.
The initial default values for the arguments are 0.01 keV, 100 keV and 200 logarithmic energy steps. If one wishes only to set the energy response range, than the <channel width> argument may be omitted. In this case, or in the case where no data file has been read in, all entries of the dummy response matrix are set to zero. Under these circumstances the dummyrsp has no physically correct way of mapping the model into the data PHA channels, so the user should not try to fit-or plot-the data while the dummyrsp is active.
The previous response matrices can be reimplemented with the response command, with no arguments. Any use of the data and notice commands will replace the dummy response with a correct set of matrices, or with no response matrix if none was originally present.