UltraVISTA is an ultra-deep near-infrared survey of the central region of the COSMOS field. This fourth UltraVISTA data release comprises stacked images in YJHKs and NB118 narrow-band filters, as well as single-band and dual-mode source lists. The data release also contains a five-band merged catalogue, created from the individual Ks-selected source lists. 

The release is based on the observations carried out from 4 December 2009 to 29 June 2016, corresponding to 58138 individual images. The total exposure time contributing to this release is 1287.5 hours, and the total survey area is close to 1.9 sq.deg. With respect to DR3, the depth in the ultra-deep stripes has increased somewhat in all five bands (0.1-0.2 mag), while the depth in the deep stripes in Ks has increased by 0.9 mag, making the depth in the Ks stack much more uniform across the full 1.5 deg x 1.2 deg UltraVISTA field. The seeing in the five stacks is in the range 0.74-0.78 arcsec.

The data products are available from the ESO Archive Science Portal or the Programmatic Access service. More details about the release content can be found in the associated Phase 3 data release description. Moreover the band-merged catalogue data, containing 451587 records, can be queried programmatically or via the dedicated Catalog Interface.

By accessing the UltraVISTA DR4, the ESO community benefits from joint efforts by ESO, the PIs of the VISTA public survey projects and their collaborators, including CALET data centers (https://calet.org/), and  CASU (Cambridge, http://casu.ast.cam.ac.uk).