  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 the HST WFC3/UVIS
instrument with the F350LP filter (346-822nm) encompassing the entire optical
band. This is the first reflected light, photometric eclipse using UVIS in
scanning mode; as such we further detail our scanning extraction and analysis
pipeline Arctor. Our HST WFC3/UVIS eclipse light curve for WASP-43 b derived a
3-{\sigma} upper 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 HST WFC3/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.
