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Our current understanding of the evolution of exoplanet atmospheres predicts the existence of a so-called .hot-Neptune desert. - a dearth of Neptune-mass planets with orbital periods less than four days comma and this prediction has so far been borne-out by observations. The discovery of LTT 9779b comma a roughly two Neptune-mass planet with an orbital period of less than a day comma thus provides a challenge to the current atmosphere evolution paradigm. LTT 9779b is currently the only known ultra-hot-Neptune comma and Spitzer-IRAC observations find tentative evidence for an atmosphere with observable molecular signatures. Although we expect the atmospheres of hot planets to be dark at UV-optical wavelengths comma TESS and CHEOPS measurements show evidence of a significant amount of light scattering from the atmosphere of LTT 9779b - likely indicating the presence of clouds. We here propose to leverage the unique capabilities of the WFC3 instrument.s UVIS channel to conduct a spectroscopic study of scattered light from the atmosphere of LTT 9779b during its eclipse. Such observations will allow us to constrain the planet.s energy budget comma as well as robustly discern the presence of comma and quantify the composition of clouds in its atmosphere. This program will be highly complementary to the planned JWST-NIRISS observations comma and facilitate a deeper understanding of one of the most unique worlds discovered to date.