  At a fraction the total cost of an equivalent orbital mission, scientific
balloon-borne platforms, operating above 99.7% of the Earth's atmosphere, offer
attractive, competitive, and effective observational capabilities -- namely
space-like resolution, transmission, and backgrounds -- that are well suited
for modern astronomy and cosmology. SuperBIT is a diffraction-limited,
wide-field, 0.5 m telescope capable of exploiting these observing conditions in
order to provide exquisite imaging throughout the near-IR to near-UV. It
utilizes a robust active stabilization system that has consistently
demonstrated a 1 sigma sky-fixed pointing stability at 48 milliarcseconds over
multiple 1 hour observations at float. This is achieved by actively tracking
compound pendulations via a three-axis gimballed platform, which provides
sky-fixed telescope stability at < 500 milliarcseconds and corrects for field
rotation, while employing high-bandwidth tip/tilt optics to remove residual
disturbances across the science imaging focal plane. SuperBIT's performance
during the 2019 commissioning flight benefited from a customized high-fidelity
science-capable telescope designed with exceptional thermo- and opto-mechanical
stability as well as tightly constrained static and dynamic coupling between
high-rate sensors and telescope optics. At the currently demonstrated level of
flight performance, SuperBIT capabilities now surpass the science requirements
for a wide variety of experiments in cosmology, astrophysics and stellar
dynamics.
