Correction factor to the noise introduced by the spatial covariance, β(N) (ratio of the real estimated error to the analytically propagated error), as a function of the number of co-added adjacent spaxels for all the DR1 V500 data. Shaded regions indicate the 1σ, 2σ, and 3σ width areas around the average value, represented by solid circles. The solid line shows the best-fitted model, following logarithmic parameter-isation, as shown in the legend.