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The HI Lyman alpha line dominates the ultraviolet emission of late type-stars. Observing Lyman alpha is vital for projects that wish to understand the chromospheric structure and behaviour of stars comma as well as modeling the chemistry and characteristics of exoplanetary atmospheres. However comma observing the Lyman alpha line is extremely difficult due to obscuration from the Interstellar Medium and telluric airglow. The numerous HST programs observing Lyman alpha lines rely on reconstruction models comma which take what parts of the line can be observed and comma via various recipes comma infer the integrated flux and profile of the rest of the line. Testing the accuracy of such reconstruction techniques is difficult comma requiring a system where the line can be observed in an obscured state and compared with the unobscured line. We have identified a system where this is possibledoublePoint A close white dwarf-M dwarf binary where the high radial velocity change over the binary orbit moves the M dwarf Lyman alpha line in and out of obscuration. We propose to obtain phase-resolved STIS spectroscopy of the system to observe the Lyman alpha line at different levels of obscuration comma which will then be tested against the maximum velocity comma unobscured line. We describe our detailed planning of the experimental set up to calculate the small investment of HST time required and account for complexities such as flaring and coronal heating. This experiment will provide an unprecedented test of the Lyman alpha reconstructions that are at the heart of multiple past comma present and (most likely) future HST programs.