I'm learning how to model stellar spectra using the IDL code, Spectroscopy Made Easy (SME), and its Python counterpart, PySME. Has anyone used these programs before? As you can see from the first attached image, the code has trouble modeling the continuum, which has been normalized. When I try to set a continuum mask by setting wavelength ranges (see second image), the ranges get shifted in the modeling... Apparently in the Valenti & Fischer 2005 paper, a solar spectrum was used and then shifted? Any help with this would be sincerely appreciated.