Another unWISE Update: The Deepest Ever Full-sky Maps at 3-5 μm

We have uniformly reprocessed ~140 terabytes of WISE and NEOWISE exposures to create the deepest ever full-sky maps at 3.4 microns (W1) and 4.6 microns (W2). Our coadds include ~4 years of observations and therefore feature ~4 times greater integer frame coverage than the AllWISE Atlas stacks. Our new, publicly available maps should find a wide range of applications, and in particular will enable the selection of luminous red galaxy and quasar targets for the Dark Energy Spectroscopic Instrument (DESI).