Observing conditions during the three transits of WASP-69 b observed with NIRPS and HARPS simultaneously. From top to bottom: Dimm seeing, airmass, and S/N of order 14 of NIRPS, where the helium triplet is located. Recording of the seeing during the transits partly ceased to function, leading to constant values. Grey vertical lines correspond to the transit contact points t₁, t₄ (dashed), t₂, and t₃ (dot-dashed).