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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., The following article has been submitted to Review of Scientific Instruments (RSI)

Balloon-borne astronomy is a unique tool that allows for a level of image stability and significantly reduced atmospheric interference without the often prohibitive cost and long development time-scale that are characteristic of space-borne facility-class instruments. The Super-pressure Balloon-borne Imaging Telescope (SuperBIT) is a wide-field imager designed to provide 0.02" image stability over a 0.5 degree field-of-view for deep exposures within the visible-to-near-UV (300-900 um). As such, SuperBIT is a suitable platform for a wide range of balloon-borne observations, including solar and extrasolar planetary spectroscopy as well as resolved stellar populations and distant galaxies. We report on the overall payload design and instrumentation methodologies for SuperBIT as well as telescope and image stability results from two test flights. Prospects for the SuperBIT project are outlined with an emphasis on the development of a fully operational, three-month science flight from New Zealand in 2020., 15 pages, 7 figures, submitted to and presented at the SPIE Astronomical Telescopes and Instrumentation 2018 conference (Austin, TX). arXiv admin note: text overlap with arXiv:1608.02502

Balloon-borne astronomy is unique in that it allows for a level of image stability, resolution, and optical backgrounds that are comparable to space-borne systems due to greatly reduced atmospheric interference, but at a fraction of the cost and over a significantly reduced development time-scale. Instruments operating within visible-to-near-UV bands ($300$ - $900$ um) can achieve a theoretical diffraction limited resolution of $0.01"$ from the stratosphere ($35$ - $40$ km altitude) without the need for extensive adaptive optical systems required by ground-based systems. The {\it Superpressure Balloon-borne Imaging Telescope} ("SuperBIT") is a wide-field imager designed to achieve 0.02$"$ stability over a 0.5$^\circ$ field-of-view, for deep single exposures of up to 5 minutes. SuperBIT is thus well-suited for many astronomical observations, from solar or extrasolar planetary observations, to resolved stellar populations and distant galaxies (whether to study their morphology, evolution, or gravitational lensing by foreground mass). We report SuperBIT's design and implementation, emphasizing its two-stage real-time stabilization: telescope stability to $1$ - $2"$ at the telescope level (a goal surpassed during a test flight in September 2015) and image stability down to $0.02"$ via an actuated tip-tilt mirror in the optical path (to be tested during a flight in 2016). The project is progressing toward a fully operational, three month flight from New Zealand by 2018, Comment: 12 pages, 5 figures, 2 tables, SPIE Astronomical Telescopes and Instrumentation 2016