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FitELP Documentation

FitELP (Fit Emission-Line Profiles) is a tool specifically designed to perform spectral emission-line fits with multiple gaussian components in echelle or long-slit data. The actual fitting procedure is based on the Non-Linear Least-Square Minimization and Curve-Fitting (LMFIT) package, (Newville et al. 2014,

The Python code was designed for the analysis of the internal kinematics of star-forming regions using echelle data. However, it can be used to model any emission-lines in both in echelle and longslit spectroscopy.

FitELP allows you to:

  • Modelling all individual emission-lines profiles with multiple-gaussian components.
  • Visualise the individual fit of the emission-lines profiles with/without residuals.
  • Perform an kinematic analysis of each target.
  • Produces pdf and latex tables with the results for each ion on each gaussian component:

   - radial velocities, velocity dispersion, fluxes, emission measure (EM), and global flux, with the corresponding errors.

   - Average of radial velocities and velocity dispersion with the corresponding errors.

   - H-alpha luminosity and the corresponding Star Formation Rate (SFR) base on Kennicutt (1998) equation, abscissa and ordinate values of the BPT-NII diagnostic diagram.

  • Visualise the different BPT diagnostic diagrams.
  • Produces latex tables with the flux, continuum, equivalent width, with the corresponding errors and for each ion.


The code is currently still in development, and there may be many issues present. Contact the authors for assistance.


If you are having issues, please let us know by submitting a GitHub issue at


The project is licensed under the MIT license.