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The HEASARC and NuSTAR teams are greatly saddened by the sudden passing of Katja Pottschmidt. Most recently Katja was the lead scientist for the NuSTAR Guest Observer Facility (GOF), a role she had supported for many years. During her science career she worked on many other high energy astrophysics missions and played an integral role in advancing our knowledge of the universe. She was a wonderful colleague and friend and will be keenly missed by all who knew her.

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gauss, zgauss: gaussian line profile

A simple gaussian line profile. If the width is $\leq 0$ then it is treated as a delta function. The zgauss variant computes a redshifted gaussian.

$\displaystyle A(E) = K{2\over{\sigma\sqrt{2\pi}(1-\mathit{erf}(-E_l/(\sqrt{2}\sigma)))}} \exp\left({-(E-E_l)^2\over{2\sigma^2}}\right) $

where:

par1 $E_l$, line energy in keV
par2 $\sigma$, line width in keV
Norm $K$, total photons/cm$^2$/s in the line

For zgauss the corresponding formula is:

$\displaystyle A(E) = K{1\over{(1+z)\sigma\sqrt{2\pi}(1-\mathit{erf}(-E_l/(\sqrt{2}\sigma)))}} \exp\left({-(E(1+z)-E_l)^2\over{2\sigma^2}}\right) $

and parameter settings are:

par1 $E_l$, source frame line energy in keV
par2 $\sigma$, source frame line width in keV
par3 $z$, redshift
Norm $K$, source frame total photons/cm$^2$/s in the line

The line is truncated at the point that the integrated flux under the line is within a critical value of the total flux. This critical value can be changed using xset LINECRITLEVEL. The default critical value is $1.0\times10^{-8}$. Note also that the normalization is defined as the integral over energies greater than zero since negative energies are unphysical.

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