CIR observed by Wind and STEREO-A which represents the region O1 in Fig. 1. Here STEREO-A measurements (red), from the same source surface longitude, have been time-shifted by ∼6 days to line up with the increase in |B|. Wind observes a clear increase in solar wind speed from 300 km s⁻¹ to 465 km s⁻¹, along with a distinctive east-west (positive-negative) deflection in the ϕ_V signature. Both spacecraft observe a similar increase in |B| and N_p, but STEREO-A only measures an increase of 320 km s⁻¹ to 350 km s⁻¹.