Central A/rN values from 1D+2D-fits to regions devoid of emission in FCC 167. Left: observed distribution of false-positive A/rN values. The grey line shows the values corresponding to regions closer to the centre, where template mismatches in the emission line cube systematically bias the A/rN values to higher values. For comparison, the dot-dashed grey lines also show the distribution of A/rN values for our candidate sources. Right: cumulative distribution for the false-positive A/rN values, 99% of which lie below A/rN = 3. A/rN values corresponding to poor fits are excluded.