Comparison between observed and synthetic Hα (top left), Bβ (top right), Ηγ (bottom left), and Hδ (bottom right) line profiles. The solid black line shows the observations, while to guide the eye the black dots show the observed profiles re-binned to about 4.5 km s⁻¹. The dashed red line indicates the Gaussian fit to the observations. The solid blue and dash-dotted green lines show the CLOUDY synthetic line profiles computed in NLTE and LTE, respectively. The central wavelengths of the Balmer lines (in vacuum) used to convert the wavelengths into velocities are 6564.60 Å for Hα, 4862.71 Å for Hβ, 4341.69 Å for Ηγ, and 4102.892 Å for Hδ.