Transmission spectroscopy near the He I triplet. Panels a and b show the 2D transmission spectroscopy maps in the stellar and planet rest frames, respectively. Tilted and vertical lines denote the position of the He I triplet, while horizontal dotted lines mark the transit contact points, t₁, t₂, t₃, and t₄. Panel c shows the spectroscopic light curve computed in a 0.075 nm band centred around the peak of absorption. Vertical dashed lines mark the transit contact points. Panel d presents the full in-transit averaged transmission spectrum.