By default, Athena smooths derivative data three times before plotting it. This is controlled by the plot->smoothderiv parameter (which can be set in the preferences dialog under the Setting menu).
When you export the derivative data, it is not smoothed. So, to reproduce Athena's plot exactly in some other plotting program, you would need to smooth the data using that tool.
Or using the ifeffit command window.... If you open the ifeffit buffer window and look at what happens when you plot the derivative, you'll see something like: set fmgb.smooth = fmgb.xmu set fmgb.smooth = smooth(fmgb.smooth) set fmgb.smooth = smooth(fmgb.smooth) set fmgb.smooth = smooth(fmgb.smooth) newplot(fmgb.energy+0, "1*(deriv(fmgb.smooth)/deriv(fmgb.energy))+0", xlabel="E (eV)", ylabel="smoothed deriv x\gm(E)", fg=black, bg=white, grid, gridcolor="grey82" , xmin=8777.58, xmax=9777.58, style=lines, color="blue", key="\gm", title="cu.xmu") pmarker "fmgb.energy+0", "deriv(fmgb.smooth)/deriv(fmgb.energy)", 8977.58, 9, orange2, 0 (Note: the "fmgb" part will be some other 4 character sequence). And if you click "Save norm(E)" you'll see something like this in the Ifeffit buffer window: set fmgb.der_norm = deriv(fmgb.norm)/deriv(fmgb.energy) set fmgb.ee = fmgb.energy+0 write_data(file="..../cu.xmu.nor", label="energy norm bkg_norm der_norm", $id_line, $id2_line, $param_line_*, $fmgb_title_*, fmgb.ee, fmgb.flat , fmgb.fbkg, fmgb.der_norm ) erase fmgb.ee erase fmgb.bkg_norm fmgb.der_norm This may look like a lot of "code", but you don't need most of it, and can just pare it down to something like set fmgb.deriv = deriv(smooth(smooth(smooth(fmgb.xmu))))/deriv(fmgb.energy) write_data(file="derivplot.dat", fmgb.energy, fmgb.deriv) If you're doing this for many datasets, you could write a macro: macro savederiv group filename set $1.deriv = deriv(smooth(smooth(smooth($1.xmu))))/deriv($1.energy) write_data(file=$2, $1.energy, $1.deriv) end macro And then use that as savederiv fmgb derivplot_group1.dat savederiv xdsa derivplot_group2.dat and so on. It's not WSYWIG, but it is more flexible -- you can easily change how much smoothing is done, for example. Hope that helps, --Matt