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We propose 10 orbits of HST WFC3-UVIS G280 slitless grism spectroscopy of S1723 comma an extremely bright gravitationally lensed galaxy at redshift z=1.3293. The proposed observations will spatially map Lyman alpha comma escaping ionizing radiation comma and the non-ionizing UV spectral slope comma on spatial scales never before obtained for an extreme emission line galaxy. Combining this new spectrum with a published HST-WFC3 G141 grism of Ha will produce maps of Lya escape fraction and ionizing photon escape fraction comma to reveal how Lyman alpha and ionizing photons are able to escape. This target has the extremely strong rest-frame UV and optical emission lines that are a hallmark of galaxies at the epoch of reionization (zvirgul7--8) comma but due to lensing magnification comma can be studied at very high spatial resolution. The target has a wealth of published data including HST multiband imaging comma a lens model comma and MMT comma Keck comma Gemini comma and HST spectra comma and is an approved target for JWST imaging and spectroscopy with NIRCam comma NIRSpec comma and MIRI comma with all data to go public as they are observed.