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recorn: change correction norm for a spectrum

This model is a replacement for and improvement on the old xspec command recornrm. If a correction file is in use for a spectrum then its normalization can be fitted for using this model. The first parameter, which is not variable, is the spectrum number and the second the correction file normalization. The starting value of the second parameter should be set to the current value of the correction file norm (this can be independently set using the cornorm command).

Note that in order to fit the cornorm parameter, the USE_NUMERICAL_DIFFERENTIATION setting in the userís Xspec.init start-up file must be set to true.† This causes XSPEC to use a slower full numerical differentiation algorithm when calculating parameter derivatives during a fit, and therefore is not recommended for general usage.

 

par1

specnum: spectrum number

par2

cornorm: correction file normalization

 

next up previous contents
Next: Redden Up: Multiplicative Model Components Previous: Pwab