SkyMapper Southern Survey (SMSS) Data Release 4 (DR4)

The SkyMapper Southern Survey (SMSS) Fourth Data Release (DR4) will provide astronomical data from across the southern sky, covering from the South Celestial Pole to up to +28 deg in declination. DR4 will include fields observed between March 2014 and November 2022, using six optical filters (uvgriz), and with a number of quality cuts applied. Measurements from over 16 billion detections covering over 24,000 square degrees of sky will be available. They correspond to over 700 million unique astrophysical objects from AB magnitudes 8 to 22. This release will also include deep and large co-added sky tiles per filter in native resolution and PSF-homogenised resolution, as well as false-colour images of the entire hemisphere. Details of the DR4 data, processing, and analysis will be described on the SkyMapper website (http://skymapper.anu.edu.au/). IVOAcompliant table access protocol (TAP), cone search, and simple image access protocol (SIAP) services are also available from the SkyMapper website, as well as through tools such as TOPCAT.