The Ultraviolet Near Infrared Optical Northern Survey

Charting the northern sky from Hawaii

UNIONS is an astronomical survey that provides answers to some of the most fundamental questions in astrophysics, including the properties of dark matter, the growth of structure in the Universe from Galactic to cluster scales, the assembly of the Milky Way, and will culminate by directly contributing to a Stage IV dark energy measurement by providing the key ground-based photometry for the ESA Euclid space mission to derive photometric redshifts. Further, in the new era of time domain and multi-messenger astrophysics, it is more important than ever to build up a very deep high quality multi-band archive of the skies to ensure a record exists of the progenitor systems that spawn the most exciting astrophysical “bumps in the night”.