Deeper detection limits in astronomical imaging using self-supervised spatiotemporal denoising

The detection limit of astronomical imaging observations is limited by several noise sources. Some of that noise is correlated between neighboring pixels and exposures, so in principle it could be learned and corrected. We present the Astronomical Self-supervised Transformer-based Denoising (ASTERIS) algorithm, which integrates spatiotemporal information across multiple exposures. Benchmarking on mock data indicated that ASTERIS improves detection limits by 1.0 magnitude at 90% completeness and purity while preserving the point spread function and photometric accuracy. Observational validation using data from the James Webb Space Telescope (JWST) and the Subaru Telescope identified previously undetectable features, including low-surface-brightness galaxy structures and gravitationally lensed arcs. Applied to deep JWST images, ASTERIS identified three times more redshift ≳9 galaxy candidates than previous methods, with rest-frame ultraviolet luminosity 1.0 magnitude fainter.