First corotating interaction region (CIR 1) that occurred during the opposition phase in 2016. Left panels: SDO/AIA 193 Å images of the source CH extracted using CATCH. The CH boundary determined via thresholding is given in red; a yellow x shows the geometrical center of mass. Right panels: in situ SW data showing proton number density (blue) and bulk speed (black) for one synodic rotation. The odd panels show SW data obtained from the OMNI database, the even panels depict MAVEN data. The heliographic coordinates of the planets at the time of SI passage are given in red in the upper right corner.