Spatial series of the velocity field, V(r), for strip L5 (A) and the corresponding first difference, δV = V(r + L)−V(r), with L = 1 lag ∼23 km (B), for the prominence at time 858.7 s. The temporal series of the velocity field, V(t), from time 747.01 s to 1747.01 s, for point A in Fig. 9 is shown in (C). Its corresponding first difference, δV = V(t + τ)−V(t), with τ = 1 lag ∼0.858 s, is shown in (D).