Best fits of Homogeneous FFA (top panel) and SSA (bottom panel) absorption models to the E1 (eastern) and W1 (western) inner lobes regions of 3C 293. A peak in the spectrum can be seen at 220–230MHz. All models provide similar quality fits to the data. The vertical lines show the ν_p frequency, for E1 (dotted) and W1 (dashed). ν_p is the frequency at which optical depth τ = 1, an is therefore a measure of the optical depth. From the model fits, ν_p for W1 is systematically higher than for E1.