SPEX X-ray spectral fitting package

SPEX is a software package for fitting astrophysical X-ray spectra. It has been developed since the 1970s at SRON Netherlands Institute for Space Research. SPEX is an interactive command-line program for the computation of emergent spectra of optically thin plasmas such as stellar coronal loop structures, supernova remnants (also including transient ionization effects), photo-ionized plasmas, and optically thick plasmas. These model spectra can be fitted to measured X-ray spectra from various X-ray observatories, like XMM-Newton and Chandra. SPEX has been optimized for high-resolution X-ray spectroscopy, which makes it especially suitable for analyzing grating and micro-calorimeter spectra.