# The unWISE Catalog: Two Billion Infrared Sources from Five Years of WISE Imaging

## TL;DR

The unWISE Catalog provides a comprehensive, deeper, and more accurate infrared source catalog from WISE data, significantly enhancing the detection of faint and crowded sources across the entire sky for diverse astronomical research.

## Contribution

It introduces a new all-sky infrared catalog based on deeper coadded WISE imaging with improved crowded-region modeling, doubling galaxy detections at redshifts 0-1.

## Key findings

- Detects sources 0.7 magnitudes fainter than AllWISE.
- Doubles galaxy detections between redshifts 0 and 1.
- Triples galaxy detections between redshifts 1 and 2.

## Abstract

We present the unWISE Catalog, containing the positions and fluxes of roughly two billion objects observed by the Wide-field Infrared Survey Explorer (WISE) over the full sky. The unWISE Catalog has two advantages over the existing WISE catalog (AllWISE): first, it is based on significantly deeper imaging, and second, it features improved modeling of crowded regions. The deeper imaging used in the unWISE Catalog comes from the coaddition of all publicly available 3$-$5 micron WISE imaging, including that from the ongoing NEOWISE-Reactivation mission, thereby increasing the total exposure time by a factor of 5 relative to AllWISE. At these depths, even at high Galactic latitudes many sources are blended with their neighbors; accordingly, the unWISE analysis simultaneously fits thousands of sources to obtain accurate photometry. Our new catalog detects sources at 5-sigma roughly 0.7 magnitudes fainter than the AllWISE catalog and more accurately models millions of faint sources in the Galactic plane, enabling a wealth of Galactic and extragalactic science. In particular, relative to AllWISE, unWISE doubles the number of galaxies detected between redshifts 0 and 1 and triples the number between redshifts 1 and 2, cataloging more than half a billion galaxies over the whole sky.