Number distribution of the [O i] line centroids running for all spaxels of the NGC 1333 map (see Fig. 1) in bins of 1 km s^-1. The dashed line indicates the location of the rest wavelength for the ³P₂–³P₁ transition of [O i] at 63.1852 μm. The distribution is to a good approximation normal and peaks at 63 191 μm, corresponding to a velocity shift of ~24 km s^-1, which is taken as the [O i] rest velocity of the system.