A sub-arcsecond, ultra-low-SWaP star tracker for small satellite attitude determination

This work presents a compact, ultra-low-SWaP star tracker achieving sub-arcsecond attitude determination. The system is validated using on-sky data from a 40 mm aperture optical assembly, and is expected to achieve an accuracy better than 1″ in LEO and ~0.2″ in GEO. The tracker derives absolute pointing (RA, Dec, and field rotation) by detecting stellar sources, constructing asterisms, and matching them in real time to a reference catalog. It supports both first-fix operation without prior knowledge and fast continuous tracking using previous solutions as priors. Performance is assessed across dense and sparse fields, the galactic plane, and regions significantly affected by dust extinction. Operational factors for LEO, including daylight-side background and Sun-avoidance constraints, are evaluated. Results show that high-accuracy attitude determination is achievable with unprecedentedly low SWaP, providing a strong sensor input for autonomous pointing control in future missions.