Helium analysis. Black dashed lines highlight the three metastable lines. Top panel: Synthetic spectrum of the K-type star used in our simulations (in black, at high resolution) and as measured with JWST/NIRSPEC in G140H-f70 mode (in red, 2.4 Å -wide pixels, ℛ = 2050) in the star rest frame. Bottom panel: Simulated differential transmission spectra as measured with NIRSPEC in the planet rest frame, averaged over the full transit and shown for different spin-orbit angles.