gabs: gaussian absorption line


\begin{displaymath}
M(E) = exp\left(-\left(par3/(\sqrt{2\pi}par2)\right)
exp\left(-.5\left(\left(E-par1\right)/par2\right)^2\right)\right)
\end{displaymath}

where:

par1 = line energy in keV.
par2 = line width (sigma) in keV.
par3 = line depth in keV. The optical depth at line center is par3/par2/$\sqrt{2\pi}$.