Data from "The Dark World: A Tale of WASP-43b in Reflected Light withHSTWFC3/UVIS"

Optical, reflected light eclipse observations provide a direct probe of the exoplanet scattering properties, such as from aerosols. We present here the photometric, reflected light observations of WASP-43b using theHSTinstrument with the F350LP filter (346-822nm) encompassing the entire optical band. This is the first reflected light, photometric eclipse usingHSTWFC3/UVIS in scanning mode; as such we further detail our scanning extraction and analysis pipelineArctor. Our HST WFC3/UVIS eclipse light curve for WASP-43 b resulted in 172 ppm residual scatter. Our observations derived a 3-σupper limit of 67 ppm on the eclipse depth, which implies that WASP-43b has a very dark dayside atmosphere. With our atmospheric modeling campaign, we compared our reflected light constraints with predictions from global circulation and cloud models, benchmarked with HST and Spitzer observations of WASP-43b. We infer that we do not detect clouds on the dayside within the pressure levels probed by HSTWFC3/UVIS with the F350LP filter (P>1 bar). This is consistent with the GCM predictions based on previous WASP-43b observations. Dayside emission spectroscopy results from WASP-43b with HST and Spitzer observations are likely to not be significantly affected by contributions from cloud particles