Comparison of the in situ magnetic field B_N component observed by MESSENGER (orange) and STEREO-A (red). The magnetic field is normalized to their respective absolute maximum value, represented in the same RTN coordinates, with a time shift and data expansion, as the MFR arrives at the spacecraft at different times and has different durations. The upper and lower horizontal axes respectively represent the STEREO-A and MESSENGER observing time. The grey shaded areas indicate MESSENGER crossings through Mercury’s magnetosphere.