A thermal bremsstrahlung spectrum based on the Kellogg, Baldwin & Koch (ApJ 199, 299) polynomial fits to the Karzas & Latter (ApJS 6, 167) numerical values. A routine from Kurucz (private communication) is used in at low temperature end. The He abundance is assumed to be 8.5 % of H by number.
Choice of fixed redshift is allowed by using zbremss variant
Choice of Hydrogen to Helium abundance ratio is allowed by using the vbremss variant.
The parameter settings are thus:
For bremss:
par1 
plasma temperature in keV 
norm 
, where D is the distance to the source (cm) and n_{e}, n_{I} are the electron and ion densities (cm^{3})

For zbremss:
par1 
plasma temperature in keV 
par2 = z 
redshift 
norm 
, where D is the distance to the source (cm) and n_{e}, n_{I} are the electron and ion densities (cm^{3})

For vbremss:
par1 
plasma temperature in keV 
par2 
n(He)/n(H) (note that the Solar ratio is 0.085) 
norm 
, where D is the distance to the source (cm) and n_{e}, n_{I} are the electron and ion densities (cm^{3})
