Magnetic field observations by MESSENGER. Top: shown from top to bottom are the magnetic field magnitude, the magnetic field components (B_RTN), and the magnetic field azimuthal and latitudinal angles (ϕ_B-RTN and θ_B-RTN). The vertical dashed line represents the IP shock arrival, and the shaded areas mark the observed MC (blue) and MC-like structure (green). Red and green lines in the ϕ_B-RTN angle panel (third) respectively denote inward and outward polarity, estimated from the magnetic field azimuth. The lower band shows the observed magnetic field polarity, where the yellow intervals represent the periods when the magnetic field was oriented close to perpendicular to the nominal Parker spiral. The grey shaded areas delimit the intervals related to Mercury’s magnetosphere, identified by eye. Bottom: shown from left to right are B_T–B_R, B_N–B_R, and B_N–B_T hodograms of the magnetic field for the periods indicated with the blue and green shaded areas in the top panels. The yellow and red points show the start and end of the hodogram for the selected periods, where the small arrows indicate the direction of the magnetic field. The orange (red) arrow indicates the direction of the rotation (partial rotation) observed within the MC (MC-like structure).