Analysis of the spectral index trend within the inner lobes of NGC 6086. Top: inner lobes of the source at 14 arcsec resolution at 4700 MHz above the 3σ threshold. The 11 regions larger than a beam that are used for the spectral index analysis are overlaid. The beam is shown in the bottom-left corner, and a reference scale is shown in the top-left one. Bottom: spectral index profile of the inner lobes in the two frequency ranges: 144–675 MHz and 1400–4700 MHz. The dashed lines represent the mean values, while the coloured regions represent the standard deviations from the mean values.