ascac: ASCA surface brightness model

Mixing model for ASCA data. Written for cluster data so uses beta or two power-law surface brightness models. Includes a calculation of the telescope effective area so no arf should be applied to input files. Note that this model is very slow if any of the parameters are free.

The model is used by reading spectra in as separate datagroups. Each input file requires an XFLTnnnn keyword set to “region: N” where N is a different number for each file (eg if concentric annuli are in use then number outwards). The normalizations for each datagroup should be linked since the ascac model takes care of the relative normalizations based on the surface brightness model used. A maximum of five different spatial regions is allowed. The absolute normalization is not reliable so this model should not be used to derive fluxes.

par1 Alpha
par2 Beta
par3 Core (arcmin)
par4 0 $\Rightarrow$ beta model,
1 $\Rightarrow$ 2-power-law