Example of the JvM correction for the peak channel of the H41α line in spectral window 1 of Band 3 for protocluster G333.60. The top left panel shows the original PSF (i.e. the dirty beam), where the red circle marks the first null. The top right panel shows the absolute value of the radial profile of the beam (black solid line) and the corresponding approximation to a Gaussian clean beam (blue dashed line). The ϵ factor, defined as the ratio of the clean-to-dirty beam volumes, is 0.32 in this example. The residuals are shown for the original image (middle left panel) and after (middle right), the JvM correction is applied. The red rectangle shows the aperture where the quoted fluxes are measured. The restored images without (bottom left) and with JvM (bottom right) correction are shown in the bottom panels.