pegpwrlw: power law, pegged normalization

A power law with pegged normalization.


\begin{displaymath}
A(E) = K E^{-\alpha}
\end{displaymath}

where :

par1 $\alpha$, photon index of power law (dimensionless)
par2 lower peg energy range (keV)
par3 upper peg energy range (keV)
norm flux (in units of $10^{-12}$ ergs/cm$^2$/s over the energy par2-par3). If par2 = par3, it is the flux in micro-Jy at par2.