Measured polarization with GRAVITY in the different observing modes. The left column shows the measurement in the off-axis mode, and the right column in the on-axis mode. In the top row, the linear polarization filter is used for the input light source; in the bottom, it is not. In all plots, the Stokes Q data points are shown in red and orange and the Stokes U in gray. The data are the average over all four GRAVITY beams. The results from the fitted model are shown in black lines.