Illustration (not to scale) of the observing strategy for the WASP-52 system. The planet orbits the central star counterclockwise, with different phase angles, φ, representing the observer’s line of sight to the system in the orbital mid-plane. During negative phase angles (pre-transit), the observer probes a potential leading tail of escaping atmosphere, while positive phase angles (post-transit) could reveal additional absorption from a trailing tail. Observations were conducted during both pre- and post-transit phases to assess the extent of atmospheric escape. For an out-of-transit spectrum, where the planet’s atmospheric contribution is expected to be minimal, additional observations were taken near eclipse, when the planet is obscured by the star.